Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1975-1979  (7,012)
  • 1965-1969  (8,330)
  • 1960-1964  (6,376)
  • 1950-1954  (3,639)
  • 1940-1944  (2,997)
  • 1915-1919  (2,525)
  • 1890-1899  (2,517)
  • 1840-1849
  • General Chemistry  (23,271)
  • Cell & Developmental Biology  (10,125)
Material
Years
Year
  • 201
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 7-13 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A new technique is described for producing and examining carbon-platinum replicas of the cytoskeleton of cultured cells. This technique allows the individual components of the cytoskeleton to be visualized and positively identified in the transmission electron microscope, and also permits an analysis of the 3-dimensional disposition of these components.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 202
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Normal swine testes, congenital cryptorchid swine testes, and normal human testes were exposed to HMM (heavy meromyosin) after either glycerination or saponin treatment in order to determine whether the fine filaments composing the crystalloids in the Sertoli cells are actin-like. The microfilaments of the crystalloids in the Sertoli cells of the cryptorchid swine testes bind HMM to form arrowhead complexes. Short bundles of microfilaments observed in the basal part of the Sertoli cells in both normal and cryptorchid testes also bind HMM. Similar bundles of HMM-bound filaments are observed in the vicinity of spermatocytes. The periodicity of the arrowhead complexes is about 35 nm, and all arrowheads on a given filament point in the same direction. In addition, the polarity of the HMM-bound filaments in a given crystalloid or bundle is uni-directional. A mechanism for the formation of the swine crystalloids has been suggested by Toyama (′75), and the results of this study strongly support this hypothesis.Fine filaments of Charcot-Boettcher's crystalloid in human Sertoli cells did not bind HMM. Therefore the fine filaments of the human crystalloid are not actin-like in nature.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 203
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 73-93 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cell junctions between endothelial cells and between connective tissue cells (leptomeninges) of the rat choroid plexus were studied by freeze-fracture. Special attention was paid to the problems of identifying fractured cell membranes and fracture faces. Tight junctions in arterioles are comprised of continuous small-meshed networks of strands appearing as shallow grooves with aligned particles on E-faces, and low ridges with some particles on P-faces. In the fenestrated capillaries the tight junctions are represented by discontinuous, isolated slightly elevated ridges with some particles on P-faces, and corresponding shallow grooves devoid of particles on E-faces. Junctions in venules appeared as a less developed version of the junctions in the fenestrated capillaries. Extended areas of the meningeal cell membranes exhibit cell junctions. Tight junctions in this tissue are comprised of a loose discontinuous arrangement of isolated, often branched junctional elements. On P-faces the elements appear as elongated crests with a distinct furrow running along the edge of the crest, occupied by a few particles. On E-faces corresponding elongated impressions are present and occupied by aligned particles and a few short bars. The arrangement of these tight junction elements are not supportive of any significant barrier function. Small gap junctions occur “freely” in the membrane, or they are sometimes surrounded by tight junction elements. Very large gap junctions (up to about 10,000 particles) are mostly surrounded and interconnected by tight junctional elements. The possible significance of the variability of gap junction size, and the relation to tight junction elements is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 204
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 257-264 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The study describes a stereological method for detecting relative changes in cells-with respect to their average volumes and to their frequencies within one cm3 of exocrine cells. The method is based on surface area ratios (Bolender, '1979) and can detect changes comparable to those obtained with the numerical density approaches (Loud, '68; Weibel et al., '69; Bolender, '74; Williams, '77). The new method requires only intersection counts- the same ones that are used for surface density estimates- and, as a result, avoids the difficult and often problematic procedures of the numerical densities. In analyzing the cellular changes in vitro, the choice of either a zero or timed control was found to exert a major influence on the results. Timed controls were required to “isolate” the experimentally induced changes from those Produced by the incubation medium.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 205
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 273-299 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two- to four- day- old beagle puppy kidneys were prepared fortransmission and scanning electron microscopy and compared to similarly prepared adult tissues. proximal tubules of puppy kidneys which contained nephrons in various stages of differentiation were examined andmaturational changes were described. Lateral surface contours of proximal tubular cells were initially smooth and relatively unfolded, but progressively acquired complex processes that may be recognized as lateral ridges and lateral-basal processes. Basal projections began as short, stubby processes and gradually took on either a narrow, plate-like or finger-like appearance. Mitochondria, lysosomes and apical vacuoles increased in number as the tubules matured. Mitochondria lacked orientation in outer cortical tubules, but exhibited some vertical arrangement within basal processes in inner cortical tubules. Despite features indicating advanced maturation of tubules in the inner cortex, puppy kidneys lacked the lipid droplets characteristic of the adult. Thus, differentiation of this portion of the developing nephron into S, S2 and S, segments was notpossible at day 4.Morphometric analyses of the lateral and basal membrane surface concentrationof proximal convoluted tubules from the puppy revealed all cells to have significantly smaller membrane area than that of the adult. However, the inner cortical cells of the puppy had a greater surface concentration than those of the outer cortex. The reduced transport capacity of the puppy proximal tubule may be related to the lack of segmentation and/or reduced lateral-basal surface area.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 206
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 317-339 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ability of the striated ducts of rat salivary glands to incorporate 3H-fucose into glycoprotein was studied by light and electron microscope radioautography. At 3.5 to 20 minutes after intravenous injection, the majority of the radioautographic grains in the ducts of the parotid gland were localized to the Golgi apparatus. By 40 minutes, the percentage of grains over the Golgi apparatus had decreased; a corresponding increase in grains occurred over small (0.1-0.4 μm) apical granules and the highly infolded basal and lateral plasma membranes. By two hours, less than 10% of the label was associated with the Golgi apparatus, while 26% and 28% were attributed to the apical granules and plasma membrane, respectively. By 8 to 12 hours after injection, the number of grains over the apical cytoplasm had decreased, suggesting luminal discharge of the apical granules. In contrast, the basal and lateral plasma membranes remained labeled up to 30 hours after injection as judged by the distribution of grains in light microscope radioautographs. Mitochondria appeared capable of independent incorporation of fucose, accounting for about 20% of the grains from ten minutes to two hours after injection. Comparable results were obtained in the striated ducts of the submandibular and sublingual glands.These results indicate that the striated duct cells readily incorporate 3H-fucose into newly-synthesized glycoproteins. A portion of these are secretory glycoproteins which are packaged and stored in the apical granules, and a portion are membrane glycoproteins which are incorporated into the extensive plasma membrane of these cells.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 207
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 431-441 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Regeneration of submandibular gland (SMG) secretory parenchyma is remarkably impaired in salivary gland diseases and under experimental conditions such as in tissue culture and after isografting. In our study acinar regeneration was found to depend on the site where the SMG tissue was implanted. Implantation of several 2-3 mm3 fragments of SMG subcutaneously in the back of the same donor adult male rat resulted in initial necrosis and mononuclear cell infiltration of the autograft. Then there was epithelial proliferation with the appearance within 28 days of lobules which contained numerous duct-like structures and only a few or no acini. In contrast, implanting SMG fragments in the anatomical bed of the donor gland resulted in the appearance of a more differentiated autograft. Although the initial tissue changes were similar to those seen in the autografts in the subcutaneous tissues of the back, the SMG autograft in the neck also contained numerous acini by 42 and 56 days after implantation. These data support the view that the implantation site influences the course of cytodifferentiation in SMG autografts.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 208
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 443-446 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The distribution of taste buds on the fungiform and circumvallate papillae of the cow tongue has been determined. The two tongues studied were from Holstein-Friesian cows four to six years of age; they contained 14,765 and 21,691 taste buds, respectively. The tip of the tongue is well supplied with fungiform papillae, and the posterior portion contains the circumval-late papillae. The midportion of the tongue contains relatively few taste papillae.The fungiform papillae contained 1,580 and 1,838 taste buds on the two tongues, respectively, and the circumvallate papillae were estimated to contain 13,185 and 19,853 taste buds. The highest concentration of taste buds therefore occurs in the circumvallate papillae; these relatively few papillae contain approximately 90% of the taste buds. On a circumvallate papilla, taste buds are found only on the papillary sidewall, with none either on the apical surface of the papilla or on the outer wall of the moat.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 209
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Samples of the rectus abdominis muscle were taken from Sprague-Dawley rats at 0, 3, 6, 9, 12, 15, 18, and 21 days of pregnancy, and at 1, 3, 6, 9, 12, and 15 days of postpartum. Sections were incubated for actomyosin adenosine triphosphatase activity following preincubation at a basic pH. Muscle fibers within a unit area of each sample were identified as to fiber type according to their enzyme activity, and the population of each type counted. The proportion of each fiber type was calculated and the diameter of 24 fibers of each type measured. No changes were noted in the muscle fiber proportions through the course of the experiment. Differential changes in muscle fiber diameters were noted in each of the three muscle fiber types. Slow oxidative fibers underwent an increase in diameter through the last half of pregnancy. The diameter was further increased as stretch of the muscle was released after birth, and did not decrease in the postpartum period. Fast glycolytic fibers decreased in diameter during the last half of pregnancy, but returned to the prepregnancy diameter in the first postpartum day. The diameter of the fast oxidative glycolytic fibers remained unchanged through the course of pregnancy and in the postpartum period.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 210
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 493-509 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The yolk sac of the Indian fruit bat Rousettus leschenaulti is unique since during the course of development it become converted into a solid, richly vascular endocrine gland-like structure with both the endodermal and mesothelial cells undergoing substantial hypertrophy. The yolk sac is progressively drawn from the abembryonic (antimesometrial side) to the embryonic pole (mesometrial side) of the chorionic sac where in late stages it comes to rest against the placental disc. The endodermal cells become grouped into clusters of acinus-like structures surrounded by the columnar mesothelial cells; the yolk-sac lumen is in most instances obliterated. Individual endodermal cells are large in comparison to mesothelial cells. The endodermal cell population varies between cells with abundant agranular ER and areas devoid of organelles to others with dense cytoplasm containing stacks of granular ER. All endodermal cells have numerous mitochondria and a few lipid droplets.The mesothelial cells are columnar with either dome-shaped, pointed or flattened apices bearing numerous elongate microvilli; within these are parallel-arranged microfilaments. While the apical cytoplasm shows the presence of absorptive tubules. coated vesicles and caveolae, the basal cytoplasm contains a few small mitochondria. Some mesothelial cells contain lipid droplets in their basal cytoplasm. On structural bases it is postulated that the mesothelial cells are absorptive in function while the endodermal cells are synthetic and secretory.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 211
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 212
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 1-21 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present study describes the development and maturation of the glomerular visceral epithelium and capillary endothelium in an attempt to clarify kidney function in the neonate. The puppy kidney undergoes nephrogenesis for at least two weeks after birth, and thus possesses nephrons of different ages and levels of maturation. Since nephron development varies considerably from inner to outer cortex, renal corpuscles were examined within three arbitrary zones (outer, middle and inner cortex). The visceral epithelium of the smallest glomeruli, i.e., those of the outer cortex, is composed of cuboidal cells which are densely clustered and rests directly upon the limited number of small capillaries. More deeply within the outer cortex, broad, flat epithelial processes extend around the capillary, but lack any visible pedicels. Mid cortical glomerular capillaries undergo an increase in diameter and length, and at the same time the podocytes flatten and separate from one another. Pedicels begin to appear in this zone as thickened, disorganized processes. Juxtamedullary glomeruli are the largest, due primarily to their extensive capillary branching (looping). Podocytes are nearly adult-like in appearance, with many long primary processes and pedicels.The endothelial morphology of glomerular capillaries varies from one loop to another, as well as within a single loop. The immature endothelium of outer glomeruli is initially characterized by extensive expanses lacking pores, multiple cellular layers and small, scattered pinholes. Greater capillary maturity is apparent in the mid cortex, due to an increase in pore number and diameter as well as greater attenuation of endothelial cells. However, evidence of remodeling and a lack of pores still exists in some capillaries. The glomerular capillaries of the inner cortex appear the most mature, but possess regions that are still immature when compared to the adult.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 213
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 23-41 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: To further characterize Sertoli cell-germ cell junctional specializations seminiferous tubules from sexually mature Sprague-Dawley rats were dissociated by enzymatic and mechanical methods. Ultrastructural analysis of cell suspensions prepared by incubation in collagenase alone or by mechanical methods revealed that spermatids remained attached to Sertoli cells or Sertoli cell fragments. Such cellular associations were found only between Sertoli cell fragments and spermatids in which the developing acrosome had made contact with the plasma membrane (step 8 and subsequent steps of spermiogenesis). Furthermore, the fragments were confined to that region of the plasma membrane over the acrosome. The Sertoli cell half of this adhesive site displayed the typical elements of Sertoli cell junctions, filamentous bundles and associated cisterna of endoplasmic reticulum, in apposition to the spermatids. The spermatids demonstrated no surface specializations at the attachment sites. In contrast, in cell suspensions prepared with trypsin, spermatids were free of attachments to Sertoli cells or their fragments. These results demonstrate that: (1) the junctions act to bind cells together, (2) adhesive type contact is established between Sertoli cells and spermatids at step 8 and subsequent steps of spermiogenesis, (3) contact is restricted to the spermatid plasma membrane over the acrosome, and (4) spermatids can be freed from the junctional specializations by treatment with trypsin.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 214
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effects of UVL-B and/or testosterone replacement therapy are compared in normal and castrated rats in order to determine whether testosterone is required for UVL-B (280-315 nm) stimulation of melanogenesis in the testosterone-dependent epidermal melanocyte system of the scrotal skin of black Long Evans rats. Testosterone is not a prerequisite for UVL-B stimulation of melanocytes as in both castrates and normal animals the melanocytes respond to UVL-B by increases in size, length and number of dendrites (dendriticness), and tyrosinase activity (intensity of Dopa reaction). Addition of testosterone to castrates does enhance the effects of UVL-B. However, UVL-B with or without testosterone cannot maintain normal melanogenesis in rats irradiated immediately after castration nor can it restore normal melanogenesis following long term castration. Both the amount of UVL energy/exposure and the number of exposures are important variables in stimulation of the epidermal melanocytes. Administration of a dose of UVL-B to castrates in a single exposure is ineffective, while the same overall dose spread over several exposures increases the size and dendriticness of melanocytes. Testosterone and UVL-B act synergistically in affecting melanogenesis although neither singly nor in combination are they able to fully restore normal melanogenesis.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 215
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Specific (A-, B- and D-) granules as well as multivesicular bodies (MVB) with a dense core from the right and left atrium of a variety of mammals (mouse, rat, hamster, guinea pig, rabbit, young and old cat) were compared by quantitative ultrastructural and cytochemical methods as regards number, size, localization and reactivity. The number of specific granules was greater in the right atrium of the rat and lesser in the same atrium of the guinea pig. In the rat this difference was due to a greater number of all three types of specific granules in the right atrium. In the guinea pig, both A and B granules were more numerous in the left atrium. A greater number of granules was also found in the left atrium of hamster, rabbit and young and old cat but the difference with the right atrium was not significant. All atria contained the same type of specific granules but A- and B-granules were present in the left atrium not only in the paranuclear area, as in the right atrium, but also throughout the sarcoplasm. In both atria, all specific granules were argen-taphobic when stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. They reacted positively to phosphotungstic acid-hydrochloric acid (PTA) (pH 0.3) as did the cell coat, residual bodies (Cgranules), lysosomes, Z-disks and a small portion of the Golgi complex. The PTA and PAS stains were abolished by acetylation, restored by saponification, unchanged by methylation and greatly diminished by sulfation. The MVB with a dense core, identical to those already noted in the cells of various endocrine glands, and thought to be crinophagic, were rare in the right atrium of all species and absent in that of the rat. They were much more numerous in the left atrium, particularly of hamsters, guinea pigs and cats and, to a lesser degree, of mice, rabbits and rats. They were silver negative. Their dense core reacted to PTA but their matrix, contrary to classical MVB without a dense core, did not.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 216
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 823-830 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cellular pattern of corpus luteal (CL) growth was studied in rats at Days 6, 10, 12, 14, 16, 17 and 22 of pregnancy: term is Day 23. Measurements were taken of the percentage of the CL occupied by luteal cells, connective tissue and vascular space, luteal cell and nuclear volumes, and the number of luteal and endothelial cells in each of three CL in both ovaries of five rats at each stage of pregnancy. Total CL volume increased from 1.08-3.23 μl over Days 10-17. This was mainly due to an increase in luteal cell volume from 3.72 pl to 9.30 pl. Neither the number of luteal cells per CL (range 212,000-287,000) nor the percentage of the CL occupied by luteal cells (range 85-90%) had much influence on growth. Nuclear volume increased roughly in proportion to cytoplasmic volume but near term it decreased despite little change in cytoplasmic volume. The number of endothelial cells per CL increased steadily from 398,000 at Day 6 to 1,545,000 at Day 22. There was a strong negative correlation (r = -0.78) between the number of luteal cells per CL and mean luteal cell volume that was evident at all stages of pregnancy. There was a positive, but weaker correlation (r = 0.35) between number of luteal cells and CL volume. Thus, CL volume seems to be partly determined by the number of luteal cells at Day 6 but this effect is moderated by local control of luteal cell volume.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 217
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 913-925 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Scanning electron microscopy of the bronchiolar neuroepithelial bodies (NEB's) in the neonatal mouse lungs was undertaken and correlated with the accompanying transmission electron microscopy. The NEB's appeared as isolated organoids along the entire length of the bronchioles, and often were located at the branching points. The boundary of the NEB's was outlined by the ciliated and Clara cells. Both granulated cells and modified Clara cells participated in the formation of the NEB. The modified Clara cells covered most of the surface of the NEB leaving only small oval areas for the exposed surfaces of the specialized cells which contained numerous cytoplasmic granules. Short and regular microvilli projected from the exposed surfaces of the granulated cells, while only sparse microvilli of irregular length were seen on the surfaces of the modified Clara cells.This scanning electron microscopy of the NEB's further established these organoids as separate morphological entities. In addition, the findings that the NEB's could be easily identified with the scanning electron microscope and subsequently dissected out for further studies would help future investigations of their functions which are not clearly known.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 218
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The proliferative response to testosterone propionate in the accessory sex glands of castrated male Balb/c mice has been studied when the glands were intact, and when the glands were unilaterally ablated. The response was analysed by serial measurements of DNA and weight, and by 3H-thymidine labelling techniques. When stimulation is started at three days after castration, most seminal vesicle cells of intact glands carry out DNA synthesis to restore preoperative cell number, whilst the smaller reduction in coagulating gland DNA prior to stimulation results in only about 30% of cells carrying out DNA synthesis to restore former levels. In the unilaterally ablated glands of the 3-day castrates, the cell kinetics of stimulated DNA synthesis and the net accumulation of DNA were similar to the intact glands. A much larger deficit in DNA was apparent in all glands of unstimulated 14-day castrates, resulting in a much larger net accumulation of DNA following testosterone stimulation. No difference between intact and unilaterally ablated glands was detected, and despite prolonged stimulation DNA levels did not exceed preoperative values. Unlike gland DNA levels, gland weights exceeded those of non-castrated mice following prolonged stimulation. However, unilateral ablation did not result in further weight increases in the remaining contralateral glands. It is concluded that the absence of the contralateral sex gland is not detected by the remaining partner during the response to the combined stimuli of a reduction in cell number (resulting from androgen deprivation), and testosterone propionate administration.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 219
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 220
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 927-937 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Morphological and functional studies on cell surfaces have been limited largely to cultured cells because of injury wrought to cells of solid tissues by commonly employed mechanical, enzymatic, or chelator dispersal methods. By using the staphylococcal epidermolytic toxin we avoided this problem; the toxin cleaves the intercellular spaces of human and mouse squamous epithelia without ultrastructural evidence of cytotoxicity. We studied the cell surface topography of neonatal mouse epidermis obtained two hours after injection of highly purified epidermolytic toxin. Immediately after sacrifice intraepithelial surfaces were exposed while the animals were immersed in fixative. Specimens were either freeze-fractured or embedded for transmission electron microscopy, or were critical-point-dried prior to platinum/carbon replication for transmission and scanning electron microscopy. Replicas could be prepared for transmission electron microscopy only if they were first stabilized with parloidion and then cleaned with both bleach and 40% chromate. By using these four complementary morphological methods (freeze-fracture, scanning electron microscopy, transmission electron microscopy of surface replicas, and standard thin sections), we could positively identify external membrane structures. The convoluted surface was studded by tenuous microvilli, scattered 15-20 nm particles, and hemispherical desmosomal mounds. Desmosomal plaques displayed randomly arrayed 15-20 nm globular particles comparable in distribution and density to particles observed in freeze-fractured desmosomes, and suggesting that desmosomal integral membrane particles span the external leaflet of the plasma membrane.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 221
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 201-211 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present study is concerned with the fine structure of the myelin sheath in rat and monkey spinal roots. Pictures are obtained that show that the intraperiod gap of the myelin sheath is continuous and opens into both the internal and external mesaxons, which in turn open into the periaxonal and endoneurial extracellular spaces. These results are compatible with the idea that the intraperiod gap is a cleft that traverses the thickness of the myelin sheath and links the periaxonal and endoneurial extracellular spaces.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 222
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 213-232 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present study extends earlier findings (Russell and Cler-mont, '76) by describing additional details of the structure, relationships, distribution, origin, and fate of tubulobulbar complexes. Freeze-fracture and thin section observations reveal few membrane associated particles and no appreciable cell coat in the membranes forming the tubulobulbar complex. The opposing plasma membranes of the complex do not appear to form a junction, although junctional formation might be expected by the close proximity (4.0 nm apart) of the Sertoli and spermatid plasma membranes. Sertoli filaments of the network which encircle the tubular portion of the complex measure 5.0-7.0 nm across and appear to insert into the Sertoli plasma membrane. Tubulobulbar complexes initially form in association with a cell surface modification (bristle-coated pit) of the Sertoli plasma membrane. The first tubulobulbar complexes develop large bulbous components (up to 2.5μm across), which soon lose connection with the spermatid and become incorporated into large phagocytic vacuoles (secondary lysosomes). As bulbs undergo dissolution, newly formed tubulobulbar complexes are observed to replace these structures. Thus, the data indicate that more than one generation of tubulobulbar complexes develop. Moreover, the tubular and bulbous portions of most dissociating complexes (as well as neighboring Sertoli lysosomes) show acid phosphatase activity. Near the time of sperm release, all complexes at the concave aspect of the spermatid head are resorbed. New tubulobulbar complexes, many lacking terminal bulbous dilations, form at the dorsal and lateral aspects of the spermatid head. These persist even after all ectoplasmic specializations and most Sertoli cytoplasm have been withdrawn from a position facing the spermatid head. The presence of tubulobulbar complexes just prior to the time of sperm release is in support of previous findings indicating that tubulobulbar complexes participate in anchoring the head of the late spermatid prior to sperm release. Past the zone of sperm release a few abnormally shaped cells, which had not been released with other spermatids of the same generation, display intact tubulo-bulbar complexes. The persistence of these and other structures may be the means by which abnormally shaped spermatids are retained and prevented from traversing the male duct system.
    Additional Material: 34 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 223
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 247-255 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A new method for impregnation of biological specimens with thermosetting resins and elastomers is described. The method has the advantage that the original relief of the surface is retained.The impregnation is carried out by utilizing the difference between the high vapor tension of the intermedium (e.g., methylene chloride) and the low vapor tension of the solution to be polymerized. After impregnation, the specimen is subject to polymerization conditions without surrounding embedding material.The optical and mechanical properties can be selected by proper choice from various kinds of resins and different procedures, for example, by complete or incomplete impregnation. Acrylic resins, polyester resins, epoxy resins, poly-urethanes and silicone rubber have been found suitable for the method.Excellent results have been obtained using transparent silicone rubber since after treatment the specimens are still flexible and resilient, and have retained their natural appearance.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 224
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the fetal rat anterior pituitary gland is described at term (day 22) and during experimentally prolonged gestation (days 23, 24, 25). The latter was achieved by daily subcutaneous injections of five mg progesterone to gravid females from the twentieth through the twenty-fourth day. Using morphological criteria for classifying pituitary cells (Moriarty, '73), six different types were observed: thyrotrophs, gonadotrophs, corticotrophs, mammotrophs, somatotrophs and non-granulated cells.During prolonged gestation (days 24 and 25 only), cells designated as cor-ticotrophs revealed changes suggesting increased activity, i.e., proliferation and dilation of the endoplasmic reticulum, dilated Golgi membranes and a reduction of secretory granules. In addition, meconium staining, which is indicative of fetal distress, was also observed on days 24 and 25. The ultrastructural changes noted suggest an increase in corticotroph activity due to fetal hypoglycemia and hypoxia which are known to occur as a result of placental insufficiency during prolonged gestation (Roux et al., '64; Vorherr, '75; Thliveris, '76).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 225
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fine structure of the scales of Fundulus heteroclitus was examined by scanning and transmission electron microscopy. The concentric ridges of the scale surface were characterized by the presence of minute, highly calcified, denticles or tooth-like processes. Needle-shaped crystals of hydrox-yapatite were precipitated not only in the osseous layer but in the intimate lamellae of the fibrillary plate except in portions just below the grooves. The calcification of the osseous layer was observed to proceed by filling the matrix with patches of crystals. The fibrillary plate appeared to calcify by invasion of crystals from the upper calcified zone into spaces between collagen fibers.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 226
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 159 (1979), S. 89-115 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retina and optic nerve of Strombus luhuanus were examined by transmission electron microscopy in order to provide an ultrastructural basis for their electrophysiological responses, described elsewhere. The retina exhibits a distinct rhabdomeric layer and layers of cell nuclei and neuropile. These layers are comprised predominantly of three cell types that can be readily distinguished on the basis of their shape, their nuclei and cytoplasmic inclusions such as vesicles and filaments. One type of cell, apparently a photoreceptor that depolarizes in response to photic stimulation, possesses a long distal segment with microvilli; such distal segments comprise the bulk of the rhabdomeric layer. A second cell type, which appears to be supportive in function, contains a bundle of tightly packed tonofilaments that extend across the retina from the capsule to the vitreous body; this cell is quite narrow except in the region near the rhabdomeric layer, where it is expanded and wraps around the other cell types. A third type of cell possesses many short microvilli that project from its apical end into the rhabdomeric layer; it may be a second type of photoreceptor or another type of neuron. The retina also contains bundles of cilia that appear to project from a possible fourth type of cell. The layer of neuropile contains numerous processes that exhibit a variety of vesicle types and structures generally associated with synapses; these appear to play a role in mediating inhibitory and excitatory interactions between the retinal neurons. The optic nerve exhibits two populations of fiber distinguishable on the basis of mean diameter. Fibers in these two populations apparently yield “on” and “off” discharges in response to photic stimulation of the eye.
    Additional Material: 29 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 227
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When Aedes aegypti females first emerge as adults, their oocytes possess no yolk. The abdominal fat body cells contain large quantities of lipid, protein, and glycogen, and possess many free ribosomes, but have very little rough endoplasmic reticulum (RER). When the females are starved for four days, their oocytes form fine lipid and protein yolk endogenously, the latter being located mainly around the nucleus. The adipocytes in these fasted mosquitoes have greatly reduced amounts of lipid, protein and glycogen and contain many cytolysosomes. Seven hours after 4-day-starved females had fed on blood, their oocytes begin filling with exogenous protein yolk at the oolemma, and lipid arises endogenously throughout the ooplasm. At this hour, the fat cells have synthesized more RER than is seen in unfed controls. Twenty-four hours post blood meal, the follicle cells have secreted discrete endochorionic plaques onto the oolemma. At this period, the adipocytes are densely filled with RER, and show for the first time many Golgi bodies and protein inclusions. They have noticeably less glycogen than at seven hours. Within 48 hours after mosquitoes have fed on blood, the endochorion forms a continuous layer around the steadily enlarging egg which is synthesizing additional protein and lipid yolk. Concurrently, the adipocytes show a greatly increased amount of glycogen and a significant reduction of RER. By the sixtieth hour after the blood meal, the follicle cells are attenuated, and the fat cells have less RER and more glycogen than at 48 hours. The nurse cells steadily decrease in size during vitellogenesis and release material onto the micropyle.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 228
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 159 (1979), S. 221-232 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The electron microscopical structure of the type “B” cells in the rectal pad epithelium of Locusta is described. The type “B” cells occur singly in the distal region of the rectal pad epithelium. They are characteristically goblet shaped and join with contiguous type “A” or rectal pad cells, near the apical surface by means of a restricted region of septate desmosomes. Type “B” cells possess a microvillate apical membrane, with the villi arranged as a rosette overlying the apical inaginations of adjacent type “A” cells.Large numbers of microtubules and vacuoles of various sizes containing an assortment of inclusions are present in the apical region of the type “B” cells. Many of the microtubules insert distally on hemidesmosomes located in the apical plasma membrane. Rough endoplasmic reticulum and mitochondria are also present but neither are abundant. The possible significance of these findings is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 229
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 159 (1979), S. 233-243 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Patterns of tracheation in the abdominal central nervous system and the cerci of Acheta domesticus are described from whole mounts, and light and electron microscopy.The tracheal supply of the ganglia is derived from ventral longitudinal tracheal trunks which have segmental connections to the spiracels. Each abdominal ganglion is served by a single pair of tracheal trunks, except the terminal ganglion, which has two pairs. Within the ganglia, tracheoles occur principally in association with glia-rich areas of the neuropile. We suggest that the respiratory exchange may be concentrated in the cell bodies of neurons and glia. Each cercus has a tracheal supply in paralle with a large air sac which, it is suggested, serves to lighten the cercus, functions as a resonator for sound reception, or facilitates tidal flow of hemolymph and postecdysial expansion of the cercus. No tracheae run continuously between ganglia or between the terminal ganglion and the cerci, and they do not appear to have a potential role as a contact guidance pathway for cercal nerve growth.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 230
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 159 (1979), S. 311-329 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal development of the urostyle is described during late stages of metamorphosis in five species of anurans: Xenopus laevis (Daudin), Bufo americanus Holbrook, Pseudacris triseriata (Wied), Hyla chrysoscelis Cope, and Rana pipiens Schreber. The developing urostyle of all five species is composed of essentially the same cartilaginous elements: one pair of basidorsals above the notochord and the subtended hypochord. Among the five species there is variation in such details as the number of spinal nerve foramina and the degree of fusion of the basidorsals; however, both the hypochord and basidorsals are very similar in all five genera examined. Consideration of the literature suggests that contradictory descriptions of the developing urostyle result from (1) varied methods of study (alizarin-staining of whole specimens or serial cross-sections), (2) the variety of species examined, and (3) the particular stage of development of the tadpole described by an investigator.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 231
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 160 (1979), S. 165-168 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A biomechanical model of the jaw mechanism in some reptiles is presented. Symmetrical muscle activity that produces equal forces on both sides of the head is assumed. The model predicts the position of the most posterior bite point and offers a functional explanation for this prediction. Turtles are used to illustrate the idea.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 232
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A stress analysis of the primate mandible suggests that vertically deep jaws in the molar region are usually an adaptation to counter increased sagittal bending stress about the balancing-side mandibular corpus during unilateral mastication. This increased bending stress about the balancing side is caused by an increase in the amount of balancing-side muscle force. Furthermore, this increased muscle force will also cause an increase in dorsoventral shear stress along the mandibular symphysis. Since increased symphyseal stress can be countered by symphyseal fusion and as increased bending stress can be countered by a deeper jaw, deep jaws and symphyseal fusion are often part of the same functional pattern. In some primates (e.g., Cercocebus albigena), deep jaws are an adaptation to counter bending in the sagittal plane during powerful incisor biting, rather than during unilateral mastication.The stress analysis of the primate mandible also suggests that jaws which are transversely thick in the molar region are an adaptation to counter increased torsion about the long axis of the working-side mandibular corpus during unilateral mastication. Increased torsion of the mandibular corpus can be caused by an increase in masticatory muscle force, an increase in the transverse component of the postcanine bite force and/or an increase in premolar use during mastication.Patterns of masticatory muscle force were estimated for galagos and macaques, demonstrating that the ratio of working-side muscle force to balancing-side muscle force is approximately 1.5:1 in macaques and 3.5:1 in galagos during unilateral isometric molar biting. These data support the hypothesis that mandibular symphyseal fusion is an adaptative response to maximize unilateral molar bite force by utilizing a greater percentage of balancing-side muscle force.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 233
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 161 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 234
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 160 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 235
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 160 (1979), S. 299-321 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Nematode amphids are a pair of lateral cephalic sense organs, each comprising a group of sensory endings terminating in a cuticle-lined pit. In Syngamus trachea, a parasite of birds, each amphid is surrounded by two non-nervous supporting elements, a large gland cell basally and a smaller supporting cell anteriorly. The amphidial glands display high levels of secretory activity from five to six days postinfection. Secretory material is discharged through the lumen of the sense organ onto host tissue. The ultrastructure of amphids and amphidial glands has been investigated in newly moulted, immature and mature adults to trace the development of glandular activity and its effect on amphid-amphidial gland relationships. In newly moulted adults, the glands have very low levels of secretory activity and appear to act only as supporting cells to the amphids. As secretory activity increases, the gland cell membrane surrounding the sensory endings is elaborated into a reticulum which probably forms the secretory surface. In mature adults the amphid pit is swollen and filled with secretion; the sensory endings are relegated to the periphery of the lumen. It is suggested that amphidial glands develop from typical supporting cells, but acquire a new role possibly associated with parasite attachment.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 236
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 160 (1979), S. 209-221 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In D. melanogaster the cross-sectioned nerve of the leg-like antenna in the homeotic mutant Antennapedia was ultrastructurally compared with the nerves of the morphologically related second leg and the wild-type antenna. The nerves of the normal antenna and the second leg differ from one another in both the numbers and arrangement of axons. According to these criteria the nerve of the homeotic appendage was structurally identified as a leg nerve.Most of the antennal nerves studied showed a consistent grouping of axons in the profile. This suggests that the assemblage of the axons does not occur randomly, but in an ordered fashion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 237
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The thymus glands of adult slimy salamanders (Plethodon glutinosus) were examined by light and electron microscopy with the objective of describing the populations of epithelial cells believed to be secretory. The results of various histochemical procedures designed to demonstrate nucleic acids, proteins, lipids, and mucosubstances were evaluated by light microscopy. Each thymus is incompletely subdivided into a variable number of interconnected lobules by trabeculae extending inward from a thin capsule composed of connective tissues. The thymic parenchyma lacks distinct cortical and medullary regions, although developing lymphocytes and plasma cells tend to accumulate in larger numbers in the outermost portions of the gland. Basophils are found regularly in the capsule and trabeculae, but only very rarely within the thymic parenchyma. The epithelial cells of the thymus can be classified into five categories: epithelial reticular cells; three varieties of granulated cells (types I, II, and III), and myoid cells. Epithelial reticular cells form a three-dimensional network which extends throughout all portions of the thymus. Type I and type II granulated cells can be distinguished from one another by various morphological criteria at the ultrastructural level, but only small differences in the composition of their inclusions can be demonstrated histochemically. Both types of granules are composed principally of a proteinaceous material containing an abundance of primary amino and guanidyl groups. In addition, most type I inclusions possess a lipid component that cannot be demonstrated in type II granules. Type III granulated cells possess very small cytoplasmic inclusions resembling those of gastroenteric endocrine cells. Myoid cells contain concentrically arranged myofibrils composed of sarcomeres. In favorably oriented material, small cysts can be identified whose walls are composed of mixtures of type I cells, type II cells, and epithelial reticular cells. Groups of degenerating epithelial cells form lamellated structures corresponding to Hassall's (thymic) corpuscles.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 238
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A detailed morphometric study of the basilar membrane was made from serial sections and graphic reconstructions of the cochlea of three little brown bats. Four distinct morphometric changes were observed within the basilar membrane. First, between 0-1.4 mm from the basal end of the cochlea, there is a rapid increase in width and cross-sectional area of the basilar membrane. Secondly, between 1.4-2.5 mm, there is little change in width of the basilar membrane (its cross-sectional area is at its greatest in this region). Thirdly, between 2.7-3.1 mm, there is a sudden decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. Finally, between 3.1 mm and the apex, there is a gradual decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. The magnitudes of the cross-sectional areas of the scalae media and vestibuli decrease from base to apex, but this is not true for the scala tympani. The cross-sectional area of the scala tympani appears to decrease from the base to 0.7 mm, then it increases up to 1.4 mm, and then it decreases to the apex. These morphometric changes in the basilar membrane of the little brown bat are compared to those in other echolocating and non-echolocating mammals. The significance of these changes is discussed in relation to the range of hearing in the little brown bat.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 239
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 161 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 240
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 161 (1979), S. 157-167 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mouthparts of female Corethrella brakeleyi and C. wirthi were studied using light and electron microscopy. Mandibles, hypopharynx and labium are highly sclerotized and are modified for obtaining blood meals. All structures were larger in C. brakeleyi than in C. wirthi except mandibular and hypopharyngeal teeth; these were smaller and more numerous in C. brakeleyi. The labium of both species terminates in peg-like structures which are similar to those reported from several genera of mosquitoes. Sensillae on the second segment of the maxillary palps appear to be identical to those described in both biting and nonbiting male and female blackflies.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 241
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 162 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 242
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 162 (1979), S. 275-309 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to provide an ontogenetic basis for the establishment of tetrapod muscle homologies and for the analysis of complex mammalian muscle states, a descriptive analysis of the morphogenesis of the thigh of Mus musculus has been made. The pattern and sequence of muscle cleavage and the migrations of individual muscle primordia are characterized from the eleventh day of gestation, when cleavage begins, through early neonatal stages. Observations on skeletal differentiation and lumbosacral plexus formation are also included. Thigh muscle morphogenesis is compared to that in the lizard, Lacerta, (Romer, '42) and the chick (Romer, '27) and homologies identified. An ontogenetic basis for the definition of ancestral and derived muscle states is provided in muscles that are morphologically variable in mammals. These include the gluteus minimus, gracilis, adductor brevis and several hamstring muscles. Certain muscles that show variable innervation patterns in adult mammals, i.e., pectineus, quadratus and adductor magnus, typically develop from premuscle regions that separate muscle anlagen innervated by different nerves. Two muscle anlagen appear in the embryonic mouse thigh and then disappear late in prenatal or early postnatal development. Comparisons with other mammals, especially the marsupial, Marmosa, reveal that these muscles are phylogenetic vestiges that degenerate before maturity. A sartorius vestige is identifiable through the thirteenth day of gestation. A tenuissimus anlage is present until shortly after birth and is clearly innervated by a branch of the peroneal nerve.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 243
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Differentiated Malpighian tubules of Periplaneta americana nymphs consist of four distinct regions. The distal, middle, and proximal regions are similar to the same regions in adult tubules. However, the transparent portion of the middle region was found to have ultrastructural characteristics different from those of the longer opaque segment of the middle region and the two other tubule regions. This newly distinguished region is called the lower middle region. Transitional zones, areas where cells show characteristics of two adjacent regions, are apparent between the distal and middle regions and between the middle and lower middle regions.The middle region of primary tubules undergoes an increase in autophagic activity and a modification of its basal infoldings and microvilli shortly before each molt. An increase in autophagic activity is also observed in the lower middle region near the time of molting.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 244
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 161 (1979), S. 169-175 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vascular anatomy of five beavers (Castor canadensis) was studied by dissection and injection of arteries and veins with vinyl acetate. There is extensive countercurrent arrangement of arteries and veins distal to and including the common iliac artery and veins. Two types of countercurrent vessels occur (1) a venae comitantes type in which two or three veins surround a central artery, and (2) a modified rete type. The retia are located proximal to the large flat tail and the webbed hind feet. Two bypass veins are described for the feet and tail and the significance of these structures in temperature regulation is stressed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 245
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 161 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 246
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 163-177 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Pilocarpine HCl, a parasympathomimetic drug, was administered to pregnant white rabbits in a daily subcutaneous injection of 5 mg/kg on days 24 through 27 of gestation. Fetuses from these animals and from salineinjected controls were obtained by caesarean section at day 28 of gestation. Light microscopic examination revealed thinner alveolar septa in the lungs of pilocarpine-treated fetuses and, morphometrically, a significant increase in the number of mature type II cells, both per unit area and per 1,000 lung cells of any kind. Examination by electron microscopy revealed that the alveolar epithelium of pilocarpine-treated fetuses demonstrated morphologic correlates of increased maturation. These included thinning of type I cells to form blood-air barriers and substantial reductions in the glycogen content of both epithelial cell types. Type II cells of pilocarpine-treated fetuses contained (as indicated by morphometric analysis) more and larger lamellar inclusion bodies, as well as more multivesicular bodies than those of controls. Biochemical determination indicated that the glycogen content of fetal lung, but not liver, was reduced significantly in the pilocarpine-treated group. The findings of this study indicate that maternal administration of pilocarpine results in increased maturation of the fetal alveolar epithelium, thus providing a basis for the autonomic manipulation of fetal lung maturation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 247
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Pyroantimonate has long been used as a cytochemical technique for the localization of cations. Although the technique was originally alleged to be specific for Na+, other cations, including Mg++, Ba++, Ca++, Zn++ and polycationic amines, form pyroantimonate precipitates. In seminiferous tubules treated with antimonate-osmium fixation, the nuclei of the Sertoli cells and germ cells contained precipitates. In regions of condensed chromatin the precipitates were dense while, in dispersed chromatin, precipitates were sparse or absent. It is postulated that the dense precipitates observed in the condensed chromatin may represent an accumulation of calcium that may facilitate chromatin condensation. The Sertoli cell nucleolar apparatus contained light precipitates in the pars amorpha, moderate precipitates in the nucleolonema, and heavy precipitates in the perinucleolar heterochromatin bodies. The nuclei of the maturation-phase spermatids lacked any precipitates. The perinuclear ring of the acrosome-phase spermatids contained pyroantimonate deposits. In the maturation-phase spermatids, staining occurred in the postacrosomal dense lamina, in the subacrosomal space between the perforatorium and the inner acrosomal membrane, and in the central mass of the residual bodies. Since the postacrosomal dense lamina is the portion of the spermatozoon that initially fuses with the ovum, it is postulated that its cationic properties in some way facilitate this fusion.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 248
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 291-320 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The hamster renal pelvis has been studied by means of low-power light microscopy, scanning electron microscopy and morphometric analyses. The results of this study are highly suggestive that the contact of pelvic urine with the other medulla as well as with the inner medulla may be an important aspect of final urine formation. The outer medulla constituted nearly 50% of the total pelvic surface area, with the inner stripe of the outer medulla more than twice the pelvic surface area of the outer stripe of the outer medulla. The large outer medullary pelvic surface area was accounted for by the elaboration of the upper pelvic walls into peripelvic columns, opercula (“secondary pyramids”), fornices and secondary pouches. A thin simple-squamous to low cuboidal pelvic epithelium separated pelvic urine from outer medullary parenchyma. The inner medulla which constituted about one quarter of the total pelvic surface area was covered by a cuboidal to columnar pelvic epithelium which appeared morphologically similar to the papillary collecting duct epithelium. Tubules and capillaries of the inner medulla did not appear as closely juxtaposed to the pelvic epithelium as did those of the outer medulla. Cortical tissue comprised only 11.7% of the total pelvic surface area and was covered by transitional epithelium similar to that of ureter and bladder. The previously reported impermeability of this epithelium suggests that pelvic urine contact with the cortex is unimportant in final urine formation. The rich layer of smooth muscle under the transitional epithelium probably functions to move urine into and out of the pelvis during pelvic peristalsis, which has been observed in vivo.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 249
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 393-417 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The human cochlear nuclei are composed of a ventral and a dorsal nucleus which are similar, though not identical, in their cytoarchitecture to those of other mammals. The ventral cochlear nucleus (VCN) consists of a rostral area of spherical cells, a central area of multipolar and globular cells, a posterior area of octopus cells, and a laterodorsal cap of small neurons. The interareal boundaries are less distinct in man than in the cat. The central region of multipolar cells and the cap area of small cells constitute the bulk of the human VCN. The spherical, globular, and octopus cells appear relatively less numerous in man than in other mammals. The dorsal cochlear nucleus (DCN) in man is relatively large, but lacks the typical stratification seen in other mammals, with only vestiges of the granular and molecular layers remaining. Virtually the entire DCN consists of an area of cochlear fiber neuropil containing pyramidal cells, small neurons, and occasional giant cells. The pyramidal cells have lost their typical radial orientation and lie scattered within the cochlear neuropil. Thus the entire human DCN may be equivalent to layers 2 and 3 of this nucleus in other mammals. In spite of the relatively large DCN, the acoustic striae appear small. This is in contrast to the large trapezoid body leaving the VCN. Intrinsic and descending fiber pathways to the cochlear nuclei are not clearly defined and may be less prominent in man than in the cat.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 250
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Growth sites within the cartilaginous nasal septa of four different species of animals (5-day-old rats, rabbits, guinea pigs and beagles) were identified by monitoring cellular proliferation radioautographically. A statistical analysis (MANOVA) was employed. It showed that, of the six combinations compared (rat-beagle, rat-guinea pig, rat-rabbit, beagle-guinea pig, beagle-rabbit, and guinea pig-rabbit), in only one (beagle-guinea pig) was there any similarity in growth pattern. The other five combinations all were significantly different. Since no particular areas emerged, with any consistency, as common growth sites within any of the four kinds of septa, it was concluded that the nasal septum might well play a passive role in midfacial growth, rather than an active role as previously thought.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 251
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 497-507 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The hypothalamic arcuate nucleus in the male little brown bat Myotis lucifugus lucifugus was studied with the electron microscope. Animals were killed by intracardial perfusion at each season throughout the year so that the arcuate nucleus could be examined for seasonal variations in morphology. Striking seasonal changes in the fine structure of ependymal tanycytes lining the arcuate nucleus were observed. Tanycytes in animals collected in the fall and early winter exhibited pale processes characterized by a scant internal framework of microtubules and fine filaments. These processes, which were found throughout the arcuate nucleus, exhibited simple irregular shapes. In animals collected between January and June, tanycyte processes contained dense accumulations of fine filaments intermingled with microtubules, and projected long attenuated extensions that often formed multilamellar sheets around axodendritic terminals or other neuronal elements. Tanycyte processes of animals collected in July and August were densely packed with microtubules and fine filaments. The processes radiated elaborate multilamellar extensions that encapsulated axons, dendrites and even entire neuronal perikarya. Multilamellar sheets consisted of as many as 10 or 12 closely spaced gyres. The seasonal variations in tanycyte structure are suggestive of astrocyte-like behaviour. These changes are discussed with respect to seasonal changes in hypothalamic neuroendocrine activity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 252
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: During embryonic development the medial part of the somite disorganizes or breaks up into sclerotomal cells which, according to many published reports, migrate medially to surround the notochord. The purpose of the study was to determine whether these cells actually migrate medially toward the notochord. Distances were measured between the notochord and the adjacent neural tube and the somite or its remnant during the period of somite disorganization. Serially sectioned, normal 10.5- to 13.5-day (d) rat embryos were used. Only transverse sections through the middle of the fourth cervical (C-4) body segment were measured, corresponding to the level of somite No. 8 (10.5 d) or its dermatomyotome remnant (10.5-11.5 d) or spinal nerve C-4 (12.5-13.5 d). Measurements were taken at six stages from photographic montages, all of which were made at precisely the same magnification. The notochord was the central axial structure from which the measurements were determined. The changes in distance show that during the period of somite breakup the neural tube grows dorsally, away from the notochord which lies adjacent to its ventral surface. Simultaneously the somite remnant moves laterally and dorsally, all the while maintaining its position relative to the overlying ectoderm and leaving behind a trail of sclerotomal cells.Also at each stage cell counts were made on the medial sclerotomal region of the C-4 segment. The average counts reveal that not only does the total number of cells increase substantially over the three-day period (42-7,546), but also the total number of mitoses (3.5-200), while the mitotic index decreases (9.0-2.7). High proliferative activity is apparent in the medial sclerotomal cells throughout the 3-day period. The evidence supports the conclusion that local proliferation of the trailing cells, which were left by the somite remnant as it moved dorsolaterally, causes the subsequent increase in density of the perichordal tissue, rather than an influx of migrating cells. Instead of sclerotomal cells migrating medially toward the notochord, the present study suggests that these cells retain their position relative to the notochord or central axis and that the medial sclerotomal region forms as a result of the growth movements of the surrounding structures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 253
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 15-29 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Clara cells in the terminal bronchioles of mouse, rat, rabbit, calf and human were compared by light, transmission and scanning microscopy, and species-differences were clearly present. Mouse Clara cells were most numerous and mouse and rabbit Clara cells had large dense mitochondria. Rabbit and calf had glycogen in Clara cells and rat Clara cells had the most variability in secretory granules, some of which had a crystalline structure. Calf Clara cells had deeply indented nuclei. Human Clara cells had the most prominent nucleoli and lacked smooth endoplasmic reticulum, which was a prominent feature of most other species. No evidence of apical extrusion or apocrine secretion of Clara cell secretory granules was observed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 254
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 545-556 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The appearance and migration of mesenchymal cushion tissue within the truncus arteriosus of the normal 2.5-to 6-day chick embryo heart was surveyed systematically with the light microscope. Series of cross-sections taken from replicate hearts at successive developmental stages allowed comparison of the following qualitative and quantitative aspects of early truncal morphogenesis. Mesenchyme within the truncus was derived from two distinct sources. The first mesenchyme appeared to migrate caudally into the cardiac jelly of the distal truncus from the nearby aortic arch region, coincident with slowing of the anterior elongation of the heart tube (Hamburger-Hamilton Stage 17-18). A second, separate mesenchymal population, derived from endocardium, began to fill the conus and proximal truncus in a radial direction, coincident with expansion of the bulbus cordis (Stage 12-19). The measured kinetics of relative cell numbers, distributions, and mitotic indices suggest substantial contributions from both sources. By Stage 26, the conotruncal region was filled with mesenchyme, which then condensed to form the anlagen of three future structures: the semilunar valves, the aorticopulmonary septum, and the tunica media of the great arteries.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 255
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 563-575 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Many mammalian muscles have a complex internal architecture. This type of structure could allow a single muscle to produce a variety of force vectors through selective regional contractions. This hypothesis was tested electromyographically in the multipinnate pig masseter by recording simultaneously from several intramuscular sites. It was found that the activity in different portions of the masseter varied systematically during the various phases of mastication. Anatomical correlates of the differential activity included fasciculus orientation and length, sarcomere length in specific jaw positions, and histochemical fiber type. The usual assumptions made about muscles for biomechanical analysis, such as uniform contraction and constant line of action, are inappropriate for complex muscles such as the pig masseter.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 256
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Scalopus membranes are characterized by: Superficial nidation; antimesometrial orientation of the embryonic disc; amniogenesis by folding; an extensive but transitory choriovitelline placenta; a large yolk sac with late and incomplete inversion; large persistent allantoic vesicle; a very broad, thin, villous, epitheliochorial chorioallantoic placenta of annular shape interrupted mesometrially, dotted with numerous areolae, and bordered by a non-villous sparsely vascular chorioallantoic membrane connected with the persistent bilaminar omphalopleure by a very narrow rim of chorion. There is no decidua. Electron microscopy shows that at 8 mm, CR, (limb bud embryo) the uterine epithelium of the interhemal membrane may be 0.5 μm or less in thickness, but that it shows no signs of degeneration. Trophoblastic microvilli often penetrate the epithelium to within 0.2 μm of its base. At this time there is active secretion by the uterine glands, and cellular hypertrophy and cytolysis of the epithelium at the gland mouths, with active phagocytosis by the areolar cytotrophoblast. The occurrence of absorptive areolae in an insectivore emphasizes the probable primitiveness of this widely distributed placental mechanism. In spite of similarities of the yolk sac to that of rabbits and rodents, the bilaminar omphalopleure produces no invasive trophoblastic giant cells. The definitive membranes of Parascalops breweri and Scapanus latimanus are like those of Scalopus. The placentae of Talpa europaea, Condylura cristata, and Neurotrichus gibbsii are discoid and relatively much smaller, thicker and more complex in internal structure. There is some reason to believe that the fetal membrane systems of moles and shrews (Soricoidea) are more like those of the ancestral mammalian stock than are those of any other recent eutherians.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 257
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 103-109 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We report a quantification of the maximum mucus accumulation in proliferating rat colonic epithelial cells. The proliferative potential was determined by radioautographic study of one-hour pulse exposures to tritiated thymidine, mucous content was determined by Periodic-acid Schiff (PAS) staining. We examined 55 labeled mucous cells in 0.5- to 1-μm serial sections. The maximum thecal and nuclear profiles of these cells were photographed and their surface areas were determined utilizing a coordinate sensor. The data were expressed as a theca-to-nucleus (T/N) ratio. The maximum (T/N) ratio for a labeled mucous cell was 3.0. We performed a similar analysis on 22 unlabeled mucous cells from upper crypt regions and surface epithelium to derive the range of (T/N) ratios for terminally differentiated mature mucous cells. The range of (T/N) ratios from these cells was from 4.8 to 16.4. Our study shows that proliferative potential of mucous cells is determined by the interrelationship between mucus accumulation and nuclear size.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 258
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 111-123 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Recently the assumed structural and functional homogeneity of the collecting duct (CD) has been questioned. The objective of this study was to determine if heterogeneity occurs in luminal surface membrane structure or in cytoplasmic configuration of cells in the collecting duct or both. Straight segments of cortical and medullary CD were examined in perfusion-fixed rabbit kidneys with scanning electron microscopy (SEM), light (LM) and transmission electron microscopy (TEM). Principal cells were the most abundant cells in all CD regions; intercalated cells comprised 37% of the cell population in the cortex, 18% in the outer medulla, and 〈 1% in the inner medulla. SEM revealed two surface patterns among the ciliated principal cells: 1, located in the cortex and outer medulla, with few surface microvilli, and 2, located in the inner medulla, with abundant microvilli. Intercalated cells exhibited four distinctive luminal surface configurations: I, numerous short microvilli; II, both short and elongate microvilli; III, microplicae alone; and IV, both microvilli and microplicae. Intercalated cells with patterns I and II were predominant in the cortex, while cells with patterns III and IV were most common at the corticomedullary junction. TEM confirmed that marked variation existed in cytoplasmic structures of both principal and intercalated cells. These findings may either indicate the presence of several specific types of principal and intercalated cells or reflect different functional states of the principal and intercalated cells. Regardless of their significance, their presence must be considered in studies seeking to establish precise structural-functional relationships in this region of the rabbit renal tubule.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 259
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 169-181 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Thyroid glands from female rats kept vitamin A deficient for one, two, and three months were examined by electron microscopy. After one month on the diet, no consistent alterations were noted. After two months, the colloid in some follicles displayed a peripheral zone of decreased density. In addition, ultimobranchial follicles within the gland had become keratinized. After two to three months on the diet, cells were seen entering the colloid. Many of these cells were identified as follicular cells since they often occurred in groups and occasionally exhibited remnants of desmosomes. Often the cells within the colloid appeared vacuolated, and by light microscopy were thought to contain lipid. However, electron microscopy revealed that these cells contained many digestive vacuoles rather than lipid droplets.Quantitative and autoradiographic studies indicated that thyroids of vitamin A deficient rats took up less radioiodide than thyroids of control rats. The keratinization of ultimorbranchial follicles in vitamin-A deficiency has been suggested as preliminary in the histogenesis of squamous cell carcinoma. However, an effect of vitamin A deficiency on thyroid follicular cells has not heretofore been reported. It's possible that the presence of follicular cells in the colloid reflects an accelerated turnover of these cells and could indicate an early pathological sign.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 260
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 265-283 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The study of Mullerian Inhibiting Substance (MIS) has been made possible because of the organ-culture bioassay devised by Picon ('69) for detecting MIS in vitro. We have studied the degeneration of the female Mullerian duct of the rat fetus, the target tissue of the assay, with electron microscopy. We have observed that the involution of the female Mullerian duct in the organ-culture assay follows a pattern of degeneration similar to the normal involution of the male Mullerian duct under the influence of MIS from the fetal testis (Price et al., '77). This involution involves alterations in the duct epithelium subsequent to a response of the mesenchyme surrounding the duct. The degeneration of a specific organ system under the direct influence of a specific factor, Mullerian Inhibiting Substance, represents an example of “programmed cell death”.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 261
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 293-299 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: By means of silicone rubber injections, we confirmed the existence of several types of aglomerular arterial pathways within kidneys of aged rats. In superficial cortex some interlobular arteries divide to form aglomerular branches (Ludwig's arterioles) towards cortex corticis. In juxtamedullary cortex these pathways are relatively more numerous, they comprise: (a) Vasa Recta Vera, (b) glomeruli in which afferent and efferent arterioles form a continuous vessel and (c) glomeruli with two efferent vessels, one by-passing glomerular tuft. In addition, results obtained in the rat by the microsphere technique are in agreement with our morphological observations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 262
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 337-351 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Mucosa from the hard and soft palates, molar gingiva, cheek and dorsal surface of the tongue of the rat was examined in the light microscope, following Mallory's triple connective tissue stain, and in the scanning and transmission electron microscopes. The epithelium covering the hard palate, gingiva, the smooth band of mucosa at the junction of the hard and soft palates, intermediate zones of the soft palate, fungiform papilla-like structures in the central zone of the soft palate, the fungiform papillae, and the more superficial part and posterior surfaces of the filiform papillae of the tongue all exhibited complete orthokeratinization. The oral surfaces of the epithelial cells in all these areas had a honeycomb pattern of interconnecting ridges surrounding depressions. Imprints of the overlying cells that had been desquamated were apparent, and the lateral boundaries between the cells were formed by two raised ridges separated by a gap. The epithelium covering the cheek, central zone of the soft palate apart from the fungiform papilla-like structures, lateral zones of the soft palate, gingival crevice, and the mucosa between the fungiform and filiform papillae of the tongue all exhibited incomplete orthokeratinization. The oral surfaces of the epithelial cells in all these areas were relatively smooth and did not exhibit a honeycomb pattern of interconnecting ridges. Imprints of the overlying cells that had been desquamated and the lateral boundaries between the cells were only very occasionally found. In the transmission electron microscope the outlines of the cells were compatible with the surface patterns seen in the scanning electron microscope. The possible relationships between the degree of orthokeratinization and ultrastructure of the various epithelia are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 263
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 525-543 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effect of estradiol and/or testosterone upon secretion by seminal vesicle in castrated and intact rats was assessed in young adult Sprague-Dawley rats, using light microscopy (LM), transmission (TEM) and scanning (SEM) electron microscopy. Hormones were injected daily for ten days beginning ten days after castrations were performed. The normal rat seminal vesicle, as revealed by SEM, was characterized by a large saccular lumen with highly folded walls. Cell surfaces were covered with microvilli, or occasionally displayed a protruding, ruffled surface, sparsely covered with short microvilli. Cytology was normal in testosterone-treated animals. Estradiol treatment of castrated animals stimulated secretion by seminal vesicle epithelial cells as evidenced by the presence of normal secretory bodies, the presence of RER, and moderately hypertrophied Golgi complexes. These glands were not heavier than were glands from castrated, untreated animals, although the epithelial cells were significantly taller. Secretion was maintained in intact animals treated with estradiol, although glands were smaller and epithelial height was reduced. Estradiol and testosterone treatment in combination did not appear to have an additive effect on secretion, weight of the gland, or epithelial height. The following results support the hypothesis that estrogen-induced prolactin synthesis and release may be involved in the mechanism by which estradiol effected stimulation of seminal vesicle epithelium. Prolactin-treated, castrated animals exhibited focal areas of stimulated epithelium. In hypophysectomized animals (untreated controls), the seminal vesicle epithelium retained some secretory bodies and secretory fluid in the glandular lumen; epithelial height was taller than that in castrated controls. Estrogen treatment reduced the epithelial height to that of castrated controls; there was no evidence of secretion. This suggests that in the absence of anterior pituitary hormones, including prolactin, the stimulatory effect of estradiol on seminal vesicle epithelium was nullified. In adrenalectomized/castrated animals, estradiol treatment stimulated secretion in seminal vesicle epithelium just as in non-adrenalectomized/castrated animals. This indicates that the adrenal gland plays a non-essential role in the action of estrogen on seminal vesicle epithelium.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 264
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 1-13 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the corpora lutea of the goat, cow, rabbit, pig and guinea pig have been examined at a stage when progesterone was being secreted by the luteal cells. Densely staining granules, 0.2 μm in diameter, are present within the luteal cells of all the species examined. Granules were detected in the extra-cellular spaces of the corpora lutea of the goat, cow and pig, but not of the rabbit or guinea pig. The luteal cells of the various species have the same basic structure but differ in the amounts of lipid and forms of smooth endoplasmic reticulum present.A common mechanism of hormone secretion, in granule form, is postulated for all luteal cells.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 265
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An antiserum which has previously been thought to be specific for LHRH- like immunoreactive material was shown to contain two populations of antibodies, one demonstrating anti-LHRH activity and the other anti -ACTH (1-24) activity. In rat and mouse, ACTH(1-4)-like immunoreactive substance is present in perikarya within the basal hypothalamus and in fibers in arcuate, periventricular and dorsomedial nuclei. LHRH-like immunoreactivity is present in fibers within the median eminence and arcuate nucleus, in a few fibers running along the ventral border of the hypothalamus, and in a small number of cell bodies within the medial basal hypothalamus.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 266
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 267
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 201-221 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The renal corpuscle of the adult lamprey, Petromyzon marnus L., is formed during the programmed period of metamorphosis. Development is initiated early in this metamorphic period and is marked by the synchronous formation and growth of rudimentary nephron units (RNU) from a longitudinal cord of nephrogenic tissue extending from the posterior tip of the degenerating larval kidney to the cloaca and connected to the peritoneal epithelium. Detachment of the RNU from the peritoneum involves autolysis and cell death and is accompanied by their branching into five or six hexagonally-arranged nephrons which radiate from the original point of attachment.Differentiation of the epithelial cells at the proximal ends of the nephrons is preceded by the widening of lateral intercellular spaces, the formation of tubular lumina (primitive urinary spaces), the loss of apical cell junctions, and the development of a capillary network with its associated mesangium. With the extension of the capillaries and mesangium between the proximal ends of adjacent undifferentiated nephrons, visceral epithelial cells (podocytes), with long cell processes (trabeculae) and slit membranes, make their appearance.The urinary spaces resulting from this form of development are lined by the epithelium of the dilated ends of the nephrons (nephric capsules). The cells of these capsules differentiate mainly into podocytes, but a few parietal cells connect to the draining tubule. This method of development explains the unique form of the renal corpuscle in the adult lamprey. Despite the type of morphogenesis, this renal corpuscle possesses the fine-structural features seen in the renal corpuscles of other vertebrates.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 268
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 185-199 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The formation and fate of cytoplasmic crystalloids in rat parotid acinar cells were investigated during ethionine intoxication and recovery. By day 3 of ethionine treatment, acinar cells had numerous autophagic vacuoles containing recognizable secretory granules and fragments of rough endoplasmic reticulum. By day 5, immature crystalloids were present in many of the autophagic vacuoles, and as the crystalloids matured, a 7-nm periodicity became apparent. Crystalloids were never observed in the Golgi saccules or in any other organelle associated with secretory granule formation. When ethionine treatment was stopped, the acinar cells rapidly returned to their normal morphology. The majority of the crystalloids and autophagic vacuoles were lost from the cells during the first two to three days of recovery. At this time annulate lamellae were present intracellularly, and macrophages, many contaning crystalloids, were associated with the basal surface of the acinar cells. These results indicate that the cytoplasmic crystalloids are formed in autophagic vacuoles, and do not represent an abnormal secretory product. Additionally, during recovery crystalloids may be removed from the acinar cells by interaction with macrophages. The sequence of autophagic vacuole formation, development of crystalloids, macrophage infiltration and phagocytosis of acinar cell debris appears to be a non-specific response of the rat parotid gland to cellular injury occurring in a variety of experimental and pathological conditions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 269
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Young and preodontoblasts and matrix vesicles which occur in the presecretory region of incisor teeth of growing rats were examined in stained and unstained ultrathin sections in order to characterize sites involved in the initial mineralization of dentin. Common to pre- and young odontoblasts in the presecretory region were hemispherical membrane-associated amorphous densities, measuring 5-35 nm in diameter after fixation in glutaraldehyde-osmium tetroxide or glutaraldehyde only. Amorphous densities were associated also with the limiting membranes of some vesicles in the extracellular matrix. Other vesicles in the extracellular matrix contained needle-like crystalline deposits typical of dentinal matrix vesicles. Fully differentiated odontoblasts in more incisal regions of the tooth lacked plasma membrane-associated amorphous densities. Neither amorphous nor crystalline densities were associated with any other cellular or subcellular structures in cells of the presecretory region. Flotation of ultrathin sections on solutions of EDTA or EGTA removed the amorphous densities from the plasma membranes, suggesting that the amorphous densities are calcium-containing mineral deposits.Amorphous deposits were associated with the membrane of vesicular structures protruding from the surfaces of pre- and young odontoblasts, suggesting that vesicles found in the extracellular matrix arise by budding from the plasma membranes of pre- and young odontoblasts. The occurrence of amorphous mineral deposits in association with the limiting membrane of some vesicles in the extracellular matrix, and the occurrence of needle-like mineral crystals within other matrix vesicles, suggest that an amorphous-to-crystalline phase transformation of mineral takes place within the matrix vesicle. The results of this study suggest that calcium-binding sites associated with plasma membranes of pre- and young odontoblasts act as nucleating centers for primary mineral deposition in tooth dentin.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 270
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 391-401 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: With the use of Golgi, horseradish peroxidase, and electron microscopic techniques, neurons within a broad region of the preoptic hypothalamus of the mouse were shown to have dendrites that projected well into the depths of the optic chiasm. Further experimental and ultrastructural investigation demonstrated synapses between these dendrites and retinal axonal boutons within the chiasm. All synapses located in the chiasm were classified as Gray's type I. The possible function of these dendritic projections is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 271
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 425-443 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The overall pattern of cephalic neurulation and the concomitant early development of the optic vesicles in mouse embryos were examined by scanning electron microscopy. Paraffin-sectioned specimens were also examined.The overall pattern of closure of the cephalic neural folds accords well with earlier observations of this process. The earliest indication of optic placode formation was seen in histological sections of embryos at the 4-ysomite stage, while optic pit formation was first observed at the 5- to 6-somite stage. The upper halves of the optic vesicles were formed in 10- to 15-hsomite embryos by the fusion of the neural folds at the junction between the mesencephalon and prosencephalon, while closure of the lower halves was associated with the closure of the rostral neuropore, and was usually completed by about the 20-somite stage.By the 25- to 30-somite stage, a rapid increase in the volume of the forebrain was observed, so that the optic vesicles were displaced laterally. An overall increase in the volume of the optic vesicles and decrease in the diameter of the optic stalks were also observed at this time. This account of cephalic neurulation and optic organogenesis provides useful baseline data relevant to the study of the normal early development of the mouse. A comparison is made between similar events in the rat, the hamster, and the human embryo.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 272
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 51-61 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The contractile, histochemical and morphological properties of fibers from red and white rat sternomastoid segments have been studied. Previous mechanical experiments suggested that both segments were fast-twitch and the present experiments were done to confirm this observation and to determine other essential characteristics of the fibers.The ATP'ase and succinic dehydrogenase (SDH) activities of fibers were determined using standard histochemical techniques. Seventy-six percent of fibers in the red segment had the high ATP'ase and high succinic dehydrogenase activity typical of fast-twitch-red fibers. Other fibers in the red segment were typically fast-twitch-white (13%) or slow-twitch-red (11%). The average cross-sectional area of red fibers was 2,104 m̈m2. Fibers in the white segment were mostly (84%) fast-twitch-white with intermediate ATP'ase activity and low to intermediate SDH activity. The remaining fibers in the white segment were histochemically typical of fast-twitch-red fibers. The average cross-sectional area of white fibers was 5,109 m̈m2. Morphologically, red fibers had three times as many mitochondria as white fibers and a Z-line thickness 38% greater than that of white fibers.Although fibers from the red segment were histochemically and morphologically different from fibers in the white segment, the isometric tension characteristics, i.e., contraction time, post-tetanic potentiation and fatigueability, were very similar and were typical of fast-twitch-fatigueable preparations. Thus, histochemical and morphological characteristics of fibers in the sternomastoid muscle are not indicative of the mechanical properties of the fibers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 273
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Peritoneal free cells from 86 adult mice of both sexes were studied quantitatively and qualitatively.Peritoneal free cells were examined by use of a Coulter counter and channelyzer. The size-distribution curves of peritoneal free cells thus obtained show three peaks, which were almost constant in position in all the cases examined. Thus, peritoneal free cells can be classified into three major populations according to cell size. The total cell numbers of the three populations, composed of small, medium-sized and large cells are, on the average, 1.60 × 106, 2.47 × 106 and 2.90 × 106 in males and 2.05 × 106, 5.57 × 106 and 3.86 × 106 in females at 65 days of age. The number of medium-sized cells is significantly greater in females than in males.Morphologically, three types of peritoneal cells, which constitute the three populations, can be distinguished cytologically and cytochemically, when examined by light microscopy and scanning and transmission electron microscopy. These type I, II, and III cells correspond closely to the three components in the size distribution curves in cell size.Type I cells are small lymphocytes. Type II cells are medium-sized, round mononuclear cells which are distinguishable from lymphocytes by their ultrastructural characteristics, and they constitute a major population which can be separated from the other two populations. Type III cells are macrophages. In the peripheral cytoplasm, they have a labyrinth of tubules which open on the cell surface. .
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 274
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 99-104 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A cell line (IT-26R21), composed only of epithelial cells, was established from normal rat thymus. Thymuses were treated with both collagenase and trypsin. Four months after the initiation of cultures, epithelial cells in packed colonies formed a monolayer and no other cells were found in cultures. Thereafter, epithelial cells have been subcultured with trypsin and EDTA, and are currently at the 30th subculture.Based upon the fine structure of the thymus in vivo, IT-26R21 cells were identified as epithelial cells from the thymus, because of their mosaic-like arrangement, desmosomes and tonofilaments. Other features also supported their origin and identity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 275
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 105-114 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Pregnant Sprague-Dawley rats were laparotomized on days 8-10 and sham-operated (S) or subjected to bilateral section of the pelvic parasympathetic nerves (pelvic neurectomy (PN)). Both S and PN animals were allowed to go to term and the time of delivery was recorded. Eight of ten S animals delivered on the afternoon of day 22 and two delivered on the morning of day 23. Pelvic neurectomy blocked parturition in five rats autopsied on day 24, and five rats autopsied on day 26. On these days the PN animals had full-term fetuses; live on day 24, but dead on day 26. In a second study, the fine structure of the myometrium of S and PN pregnant rats was examined during the parturient period for the presence of gap junctions. Gap junctions were present between myometrial smooth muscle cells of the S group during delivery and in the PN group on days 23, 24, and 25, in the absence of delivery. There was a significant increase (p 〈 0.05) in the number of gap junctions on day 23 in the PN animals. There was no difference in the length of gap junctions in the different groups. These observations indicate that the parturition block characteristic of PN animals is not attributable to the failure of gap junction formation between smooth muscle cells. Apparently, the nervi erigentes participate in the orchestration of events terminating in parturition, but their specific role remains an enigma.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 276
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 277
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 147-157 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Sertoli cells have been isolated from the newborn calf testis using a combination of mechanical and enzymatic disruption. Testicular fragments, previously chopped into 1-mm pieces, are digested in an enzyme mixture consisting of hyaluronidase, collagenase, trypsin and DNAse, followed by a second digestion in trypsin and DNAse. Isolation of the resulting cellular fractions by sedimentation with unit gravity produces an aliquot of Sertoli cells which is over 95% pure when examined by light and electron microscopy. Cultures of these cells grow rapidly and produce Mullerian Inhibiting Substance as evidenced by their ability to cause the involution of the Mullerian duct of the female fetal rat when co-cultured in an organ-culture assay system.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 278
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 231-249 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of hepatocytes, bile canaliculi, and hepatic sinusoids of the larval lamprey, Petromyzon marinus, was examined using thinsectioned and freeze-fractured tissues. The liver is a “tubular gland” with hepatocytes arranged in a tubular fashion around large bile canaliculi. Hepatocytes are roughly conical in shape, with their tapered apices facing a bile canalicular lumen. They possess extensive rough and smooth endoplasmic reticulum, a well-developed Golgi complex, abundant mitochondria, and varying numbers of large secondary lysosomes. Both secondary lysosomes and the Golgi complex are concentrated in the apical or peribiliary cytoplasm, indicating a possible role in bile secretion. The apical surfaces of the hepatocytes bear numerous elongate microvilli and occasional cilia, which project into the bile canaliculi. The hepatocytes are joined, apically, by junctional complexes composed of zonulae occludentes and adhaerentes. In freeze-fracture, the zonulae occludentes are of variable apicobasal depth and consist of honeycomb-like meshworks of fibrils. Spaces of variable width frequently appear in the P-face grooves, indicating that the zonulae occludentes are “leaky.” Numerous communicating (gap) junctions join the hepatocytes laterally. Varying numbers of lateral microvilli project into the intercellular spaces and, basally, the plasma membrane is deeply infolded, resulting in the formation of apparently interdigitating basal processes resting upon a thin basal lamina. Sinusoids are composed of both a heavily-fenestrated, continuous endothelium, and phagocytic reticulo-endothelial (Kupffer) cells. Despite the difference in arrangement of their hepatocytes, the mammalian and lamprey livers show similar ultrastructural features.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 279
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 280
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 285-291 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Luteinizing hormone and follicle-stimulating hormone were identified by immunocytochemistry in the same cells of the pituitary pars tuberalis, following hypophysectomy in the rat. A marked hyperplasia and hypertrophy of these cells occurred in response to hypophysectomy. These findings are discussed in light of the potential for hormone production by pars tuberalis gonadotropes following hypophysectomy performed as part of an experimental protocol, as well as that performed for palliation of human metastatic breast cancer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 281
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979), S. 429-429 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 282
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Data are reported which show significant regional capillary differences in left ventricular endocardium and epicardium of normal rats and of rats with hyperthyroid-induced cardiac hypertrophy. The epicardial region of control rats has 38% more capillaries than the endocardial region. Control endocardial myocytes are 62% larger in cross-sectional area than epicardial myocytes. Hypertrophic hearts exhibit regional differences in capillary density similar to those in the normal hearts, but there is an overall reduction of 12 and 17.5% in capillary density in both regions. The average cross-sectional area of myocytes increases 34.5% in the epicardium and 22.5% in the endocardium.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 283
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 81-101 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The sacculi of five species of catfishes were studied by transmission and scanning electron microscopy. In four species, the sagitta exhibited a multifluted anterior part and a tapered posterior part; in Corydoras aeneus, however, the fluted part was absent, and a vertical component extended dorsally to terminate near the opening of the transverse canal. In all species, the otoliths had a laminar structure. An otolithic membrane was present, and hair cell bundles projected into cavities on the macular surface of the membrane. Attachments of the otolithic membrane to the neuroepithelium included short extensions of the membrane to the tallest components of the hair cell bundles of the peripheral cells and more delicate connections to the kinocilium and taller stereocilia of central cells; in addition, attachments to the microvilli of supporting cells were present. In both hair cells and supporting cells single microtubules and bundles of microtubules were present; the bundles had an orderly arrangement and were associated with cytoplasmic densities surrounding the desmosomes. The hair cells were innervated by both afferent and efferent nerve endings. Studies of the polarization of the hair cells in all species (except C. aeneus) showed that there was a single longitudinal axis that divided dorsally polarized cells from those oriented ventrally. In Doras spinosissimus and Bunocephalus bicolor, an additional line of polarization was evident in a small area in the anterior part of the macula; therefore, in these forms there was a double bipolar orientation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 284
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 231-243 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The autonomic innervation of the rat ventral prostate was studied in an attempt to evaluate the role of innervation in the normal function of the gland. Specific histochemical methods for both catecholamines (the formaldehyde-induced fluorescence method, FIF) and acetylcholinesterases (the Gomori-Koelle thiocholine method) were used. The neuro-effector contacts were studied by electron microscopy using both 3% glutaraldehyde and 3% potassium permanganate (KMnO4) as fixatives. It was found that the rat ventral prostate receives dual autonomic innervation. Adrenergic fibers, which formed the majority of the nerves, were often seen in close contact with the smooth muscle cells around both the prostatic alveoli and secretory ducts. The non-adrenergic nerve fibers, which were fewer in number, did not form such intimate contacts with the muscle cells. No direct synapses with epithelial cells were detected.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 285
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 277-281 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: By iontophoretically introducing, first, cobalt and, subsequently, sulfide ions into the vagus nerve, it is possible to trace sensory nerves to their endings in the rat lung. Nerve fibers and terminals are found predominantly in the adventitia of the airways and blood vessels. Some nerves are found in the submucosa of the bronchi and bronchioles. Some are found in the cardiac muscle on the periphery of pulmonary veins, and a few nerves are seen to end among smooth muscles of the blood vessels and the airways. At least three types of nerve endings can be identified at the light microscopic level: (1) free nerve endings; (2) brush-like endings; (3) knob-like terminals.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 286
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Little information is available on the ultrastructure of macrophages in the corpus luteum or their importance in the regression of luteal tissue. In the present study, the fine structure of activated luteal macrophages during pregnancy and the postpartum period was examined by electron microscopy of guinea pig ovaries fixed by vascular perfusion. In these corpora lutea, macrophages can readily be distinguished from luteal cells. Activated macrophages typically display three prominent inclusions in their cytoplasm: (1) heterophagic vacuoles, (2) distinctive large dense inclusions, and (3) large and small electron-lucent vacuoles. In addition, they contain numerous smaller lysosome-like dense bodies. Activated macrophages in corpora lutea also characteristically show many surface protrusions, such as processes, folds or pseudopodia, which often occur in close contact with nearby luteal cells. Generally, nuclei of macrophages are irregular in shape and display a dense border of heterochromatin, thus differing from those of luteal cells.Macrophages seem to be most abundant in regressing corpora lutea, where they commonly display heterophagic vacuoles containing recognizable luteal cell fragments, evidence that these phagocytes ingest senescent luteal cells. The digestion of luteal cell components in heterophagic vacuoles presumably gives rise to the distinctive large dense inclusions typically seen in macrophages. The findings of this study indicate that macrophages play a central role in luteolysis by phagocytizing luteal cells or their remnants. They therefore appear to bring about the reduction in volume of the corpus luteum that occurs as this tissue regresses. These results taken together with those previously published (Paavola, 1978) further indicate that breakdown of the corpus luteum during postpartum luteolysis in guinea pigs involves both autophagy and heterophagy.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 287
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 288
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 485-495 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The possibility that cartilages of differing embryological origins behave as separate types with respect to cell-to-cell associations was tested by placing the cut ends of transversely sectioned embryonic chick tibial cartilages (of mesodermal origin) in apposition to transversely sectioned Meckel's cartilages (a neural crest (ectodermal) cartilage) on the surface of a semi-solid organ culture medium and maintaining the combinations in vitro for five to ten days. Tibia-tibia and Meckel's cartilage-Meckel's cartilage (homotypic) combinations, which served as controls, became united by a common extracellular matrix and by the proliferation of chondroblasts. Analysis of combinations where one partner had been prelabelled with 3H-thymidine indicated that chondroblasts intermingled at the contact zone. In contrast, tibia-Meckel's cartilage (heterotypic) combinations became separated by a layer of fibrous tissue. The chondroblasts at the contact zone failed to intermingle. We conclude that avian embryonic chondrocytes are not all equivalent and that part of their non-equivalence could be related to their embryological origin either from the mesoderm or from the ectodermal neural crest.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 289
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 557-561 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Groups of three consecutive somites from the first to the eleventh somite from chick embryos of stages 17-18 were grown in tissue culture for seven days. Sympathetic neurons, identified both by phase contrast microscopy and FIF histochemistry, occurred only in cultures which included the sixth, or more caudal, somites.If it is assumed that sympathetic precursor cells (neural crest cells) have not undergone a caudal shift prior to stages 17-18, and taking into account the loss of one or two rostral somites, then the anterior sympathetic ganglia are derived from neural crest caudal to the sixth or seventh somite Thus, the vagal zone (level with somites 1-7) contributes little to the sympathetic nervous system.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 290
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 291
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 69-81 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Adult pigeons received dantrolene sodium, a skeletal muscle relaxant which blocks the release of calcium during excitation-contraction coupling, for 12 to 16 weeks. The pectoralis muscles of these birds were analyzed for changes occurring in the various fiber types of the muscle. Both histochemistry (ATPase and SDH activity) and electron microscopy (mitochondrial and lipid volume percentages) differentiated two fiber types. The two fiber types consisted of fast-twitch glycolytic fibers (FG) and fast-twitch oxidative-glycolytic (FOG) fibers. After dantrolene treatment some FG fibers showed little or no ATPase activity. Dantrolene treatment also produced a disappearance of thick filaments in some FG fibers. We infer that the fibers without thick filaments are the ones lacking ATPase activity. The FOG fibers were nearly normal. Since drug-fed birds lose weight, a few birds were starved to determine whether the filament loss was related solely to the bird's loss in weight. No fibers in starved birds showed reduced ATPase activity or loss of thick filaments. In fibers that showed thick filament disappearance, the I-bands remained organized and intact, suggesting that the I-band maintains its integrity without interaction with the thick filaments. Changes in activity patterns may cause loss of thick filaments by inhibiting either their synthesis or assembly.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 292
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 125-129 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Interstitial cells in the interalveolar septa of lungs, which are considered to be myofibroblasts, are coupled by communicating junctions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 293
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 147-152 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Some habenular cells of the elasmobranch, Scyllium stellare, have a perikaryon completely enveloped by myelin of the compact type. They are found only in the left habenula and not in the right. The myelin sheath accompanies the proximal segment of the process arising from the perikaryon, in a node of Ranvier-like pattern. The identity of these myelinated cells and the functional significance of their myelination are unknown.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 294
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 311-317 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The purpose of this research was to describe patterns of density variation throughout the cortex of the humeral shaft in Macaca and to attempt to explain these variations in terms of the gross anatomy and mechanical function of the bone. One hundred ninety transverse sections were taken from five sites along the humeral diaphyses of 38 Macaca. The density at eight positions around each section was measured using radiographic and densitometric techniques. Analysis of variance indicated significant (p 〈 0.02) differences among cross-sectional levels and positions within each level. No sexual dimorphism in density could be demonstrated, although sexual dimorphism in density has been reported for the femora of this same sample. This relationship between humerus and femur parallels that found in humans. Density increased distally in the humerus, probably due to major areas of muscle attachment. Comparison with similar data from the femur of Macaca indicated unexpected differences in density pattern which may underlie differences in the strength and mechanics of the upper and lower extremities.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 295
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 296
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 403-423 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The renal pelvis of the hamster has been studied by light microscopy (epoxy resin sections), transmission electron microscopy, and morphometric analysis of electron micrographs. Three morphologically distinct epithelia line the pelvis, and each covers a different zone of the kidney. A thin epithelium covering the outer medulla (OM) consists of two cell types: (1) granular cells are most numerous and have apically positioned granules which stain intensely with toluidine blue, are membrane-bound, and contain a fine particulate matter that stains light grey to black in electron micrographs. (2) Basal cells do not have granules, are confined to the basal lamina region, and do not reach the mucosal epithelial surface. The inner medulla (IM) is covered by a pelvic epithelium morphologically similar to collecting duct epithelium of IM. Some cells in this portion of the pelvic epithelium (IM) stain intensely dark with toluidine blue, osmium tetroxide, lead, and uranyl acetate. Transitional epithelium, which separates cortex (C) from pelvic urine, has an asymmetric luminal plasma membrane and discoid vesicles, each of which is similar to those previously observed in mammalian ureter and urinary bladder epithelia. Based on morphological comparisons with other epithelia, the IM and OM pelvic epithelia would appear permeable to solutes and/or water, while the transitional epithelium covering the C appears relatively impermeable. It would also appear that the exchange of solutes and water between pelvic urine and OM would involve capillaries, primarily, since morphometric analysis showed that both fenestrated and continuous capillaries of the OM were extremely abundant ( 〉 60% of OM pelvic surface area) just under the thin pelvic epithelium.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 297
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 156 (1979) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 298
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The hamster uterine luminal epithelium undergoes cyclic morphological changes, which include mitosis and hypertrophy prior to ovulation and degenerative changes after ovulation. We have previously shown that the degenerative changes are symptoms of estradiol (E2) withdrawal; they occur within 24 hours after ovariectomy, can be prevented by E2 treatment, and are associated with a decline in the content of uterine nuclear E2 receptor (West et al., 1978).In this report, the results of an electron microscopic study of the uterine luminal epithelium in cycling and hormonally altered hamsters are described. During estrus and after ovariectomy, the death of numerous epithelial cells occurs by apoptosis. The ultrastructural alterations in such cells include condensation and margination of the chromatin, cytoplasmic condensation, amoeboid changes in cell shape with formation of pseudopodial extensions, and nuclear and cytoplasmic fragmentation. The cell fragments, or apoptotic bodies, accumulate near the basal lamina, and are then phagocytosed by macrophages, and possibly by neutrophils as well.The ultrastructural features of cell death by apoptosis in the hamster uterus are similar to those observed by others in a variety of tissues. Because of the periodic, hormonally regulated occurrence of extensive apoptosis in the hamster uterine epithelium during the estrous cycle, this system is well-suited for further investigations on the ultrastructural alterations that occur in cells undergoing apoptosis. In addition, apoptosis appears to be a sensitive morphological endpoint of E2 withdrawal in the hamster uterine luminal epithelium.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 299
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 483-505 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The occurrence and distribution of muscle spindles was studied in histochemically and conventionally stained serial cross sections of 6-week-old and adult rat masticatory and suprahyoid muscles. Spindles were present in moderate to large numbers in jaw closers, but they were absent in jaw openers and two of four muscles of an accessory suprahyoid group. In jaw closers, 67% or more of the total spindle population was concentrated relatively distant from the temporomandibular joint, in muscle portions which contained large numbers of extrafusal fibers reacting strongly for oxidative enzymes. Because of their location, spindles in these portions should be stretched more and, subsequently, should respond with a greater afferent discharge at any given muscle length than spindles situated nearer to the joint. Spindles in jaw closers, especially the medial pterygoid and deep masseter, often occurred in clusters and complex forms near the terminal branching of intramuscular nerve trunks. No such concentrations were seen in the two muscles of the accessory suprahyoid group that had spindles. The association in jaw closers of spindles with extrafusal fibers high in oxidative enzyme activity is consistent with the view that spindles are the sensory component of a reflex system that recruits these fibers for finely-graded contractions in response to small internal length-changes of the muscle (Botterman et al., 1978); however, in jaw openers and two muscles of the accessory suprahyoid group, the absence of spindles, coupled with the presence of large populations of extrafusal fibers high in oxidative enzyme activity, is not easily reconciled with this concept.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 300
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 507-516 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The regulatory role of estrogen on cell population kinetics in the descending colon was studied in intact female and ovariectomized mice. In the colonic crypts from intact mice, the crypt size (the number of epithelial cells per crypt column) and the proliferative activity of epithelial cells fluctuated slightly during the estrous cycle. Peak cellularity per crypt column was exhibited during estrus and early diestrus, whereas peaks in labeling index were seen during estrus and late metestrus. While the population size of mucous cells showed a minimal variation, the number of proliferative vacuolated cells per crypt column varied inversely with that of differentiated columnar cells during estrous cycle. The vacuolated cells were increased in number in the preovulatory phase and the columnar cells in the postovulatory phase.Three weeks after bilateral ovariectomy, the colonic crypt appeared to reach a new steady state, which was characterized by a small crypt size, a decrease in the number of differentiated cells, an increase in the relative number of proliferative cells and a relative increase in the proliferative activity of the crypt as compared to intact mice.When ovariectomized mice were treated with estrogen, the number of 3H-thymidine-labeled cells in the crypt was decreased as compared to untreated ovariectomized mice, the decrease being greater after a single injection than after multiple injections of estrogen, and the vacuolated-columnar cell line being affected more than mucous cell line. Meanwhile, the crypt size as well as the population size of differentiated cells in the crypt failed to return to normal after estrogen treatments. Thus, estrogen did not promote differentiation of epithelial cells in the crypt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...