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  • 1990-1994
  • 1970-1974  (906)
  • 1890-1899
  • 1973  (493)
  • 1970  (413)
  • Life and Medical Sciences  (906)
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  • 1990-1994
  • 1970-1974  (906)
  • 1890-1899
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  • 101
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973) 
    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
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973), S. 503-517 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Equine endometrial cups are localized endometrial outgrowths which develop in mares during early pregnancy and secrete pregnant mares serum gonadotrophin (PMSG).The principal cell-type found in endometrial cups is large, regular and epithelioid in appearance. These cup cells have one or two large euchromatic nuclei with dense, characteristic nucleoli. Their cytoplasm is filled with irregular profiles of endoplasmic reticulum containing pale flocculent material. Lipid droplets and a few mitochondria are also present. Golgi material is not prominent and the absence of membrane-bound secretory granules suggest that the Golgi apparatus does not package a secretory product. The plasmalemma is mostly smooth in outline but is modified in some places to form short microvilli or complex intercrescent folds.
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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973), S. 561-568 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Urogenital sinuses from 14- to 17-day old embryonic mice were grown in vitro for six days. Fourteen-day old urogenital sinuses exhibited weak, irregular peristaltic contractions, while in explants from 15- to 17-day old embryos peristaltic contractions were forceful and regular in rhythm. Neither testosterone dipropionate nor Cyproterone acetate substantially influenced contractile activity whereas estradiol was slightly inhibitory. Exposure to cytochalasin-B resulted in a complete, but reversible inhibition of peristalsis. The initiation of peristaltic contractions correlated well in time with the presumed onset of urine production by the developing kidneys, and it is suggested that these peristaltic contractions may facilitate urine transport from the kndneys to the amnionic cavity.
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  • 104
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The thymus, which undergoes spontaneous involution three weeks after birth in “lethargic” mutant mice, was studied by electron microscopy. Ultrastructural alterations observed in the involuting thymus of “lethargic” mice resemble those of acute thymic involution induced by the administration of adrenal corticosteroids. The responsive cells in thymic involution of “lethargic” mice were cortical thymocytes, macrophages, and epithelial cells. The first indication of the involution was the appearance of a large number of degenerating thymocytes in the cortex. Pyknotic nuclei of degenerating thymocytes were observed within the macrophages. Macrophages of the involuting thymus were characterized by their content of thymocyte pyknotic nuclei as well as a variety of cytoplasmic inclusions. Cytoplasmic inclusions were also found in the epithelial cells. The inclusions were of two different types: (a) tonofibrils in markedly increased numbers in relation to a non-involuted thymus, and (b) large vacuoles with dense bodies and/or myelin figures, as found in a normal cell, but several times the number one would expect to find. A large number of lipid-laden cells were found in the involuted thymus. This type of cell was not seen in the normal thymus. Numerous Hassall's corpuscles were also found in the involuted thymus of “lethargic” mice.
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  • 105
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 579-584 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ventricular endocardium of 20 rats and five dogs was examined with a scanning electron microscope after careful washing with phosphate-buffer, glutaraldehyde fixation and freeze-drying. Endothelial cells formed a continuous sheet lining the ventricle in both species. Individual cells were identifiable by a central bulge corresponding to the nucleus and were separated by a polyhedral pattern of intercellular lines. The intimal surfaces of these cells were relatively smooth, although sometimes transverse ridges, small pseudopod-like projections or indentations suggestive of macropinocytosis were present. Endothelial cells were relatively easily lost in preparation and shrinkage artefacts were also observed. These observations are compared with other scanning electron microscopic studies of endothelium and are discussed with particular reference to the effects of preparative procedures.
    Additional Material: 7 Ill.
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  • 106
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 631-637 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Electron microscopic analyses of the greater petrosal nerve, the deep petrosal nerve and the nerve of the pterygoid canal near the point of their union in the mouse were made to clarify the courses of their fibers. Most of the nerve fibers of the greater and deep petrosal nerves passed through into the pterygoid canal nerve, but in some specimens a few nerve fibers (less than 100) coursed from the deep petrosal nerve to the greater petrosal nerve or conversely. Therefore, except for these, the source of the unmyelinated fibers of the greater petrosal nerve from the deep petrosal nerve may be eliminated; these fibers may be derived from the facial nerve proximal to the greater petrosal nerve.
    Additional Material: 10 Ill.
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  • 107
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 111-120 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Lymphoid nodules and diffuse lymphocytic infiltration are common in turtle urinary bladders. Nodules, usually located immediately beneath the epithelial layer, were found in 15 of 29 different hemibladders surveyed. A whole cross-section of each hemibladder was examined in the survey. The nodules consisted of aggregates of dense lymphocytes without germinal centers. Erosion of the epithelial layer over the nodule was found in approximately one third of the cases. Scattered lymphocytes were abundant within the epithelial layer and were found in smears from the mucosal surface. Pyroninophilic cells resembling plasma cells were found in all regions of the bladder. Electron micrographs showed lymphocytes and plasma cells in the epithelial layer above the basement membrane.
    Additional Material: 9 Ill.
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  • 108
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 125-127 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have undertaken a study to coordinate examination of thin sections with that of freeze-etched material. Results suggest that (1) lamellar bodies have a much more regular structure than hitherto believed. (2) The leaflets of some lamellar bodies reveal a unique substructure of ribs and intramembranous particles displayed in form and spacing (400-500 Å) like those of tubular myelin as seen in the airspace. (3) As in other membranes of high metabolic activity the fracture face is covered with particles 80-100 Å in diameter. Our freeze-etch findings of the previously undetected organization and suborganization of lamellar bodies suggest an entirely new set of morphological criteria for evaluating the maturation of lamellar bodies and their role in the intracellular assembly of the reticular components of the airspace lining.
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  • 109
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 181-183 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Explants of human adipose tissue were maintained for one week in vitro and the effect of iodoacetate, insulin and of the medium glucose concentration on cell size determined. In the presence of iodoacetate the mean cell size remained unaltered indicating that the morphologic changes reflect the cellular rates of metabolism. Addition of insulin did not prevent a decrease in mean cell size of explants with a large initial mean offering indirect, morphologic evidence for the insulin resistance in large adipocytes. The data support our previous suggestion that the cellular insulin sensitivity is an important parameter to control adipocyte size and, hence, enlargement of the adipose tissue.
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  • 110
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 205-223 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the epithelium of different parts of the rat vas deferens was studied in normal rats and at intervals of up to nine months after vasectomy. The cytology of the columnar epithelial cells showed regional variations particularly in the type and extent of endoplasmic reticulum. Cells of the proximal part of the vas deferens were characterized by basal and perinuclear granular endoplasmic reticulum, a large Golgi apparatus, and numerous apical microvilli, vesicles, and vacuoles. In contrast, the columnar cells of the distal portion of the vas deferens contained large amounts of smooth endoplasmic reticulum, much of which assumed the form of large whorls of smooth membranes. In the distal segment the number of microvilli, vesicles, and vacuoles was less but mitochondria were more numerous than in the proximal part. Cells in the middle portion of the vas deferens showed some features of both proximal and distal parts. These structural characteristics, along with previous experiments, suggest that in the proximal portion of the vas deferens absorption of material from the lumen is an important function, while the cells of the distal part may synthesize steroids. Thus, these regional differences in ultrastructure probably reflect regional differences in function along the length of the vas deferens. After vasectomy the regional specializations were retained and did not appear to be altered. The possibility that this structural and functional sequence is significant for normal fertility and its relation to attempts to reconnect the vas deferens after vasectomy are considered.
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  • 111
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 273-278 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The grey lethal mouse is an osteopetrotic mutant which cannot be identified by its external appearance (grey fur) until eight days of age and dies within one month of birth. Techniques for the identification of neonatal mutants would greatly facilitate study of the pathogenesis of osteopetrosis and its early treatment.Under hypothermal anesthesia, the left lower limbs of neonatal mice were amputated just above the knee joint. The external appearance of two day old amputated tibiae could be correlated with the external appearance of the mice at eight days of age. The diaphyses of normal tibiae appeared red under the dissecting microscope due to the presence of hemopoietic tissue occupying the central marrow cavity. Grey lethal tibiae appeared opaque because relatively more unresorbed bone occupied the center of the diaphysis.Histologic examination showed that in normal mice at birth, the mandibular incisor extended posteriorly to the molar region of the jaw, but that in grey lethals dense bone prevented the incisor from growing posteriorly in this fashion.
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  • 112
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 255-517 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 113
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 561-577 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Seventy-five human embryos, at stages ranging from XII to XVIII of Streeter's horizon, four to six weeks postconceptional age, were obtained from healthy women by curettage. Limbs were cultured in nutrient agar medium for four to 18 days. Excepting a few cases which resulted in total necrosis, differentiation of mesenchyme into cartilage or bone primordia and other supporting tissues took place similarly to in vivo, though it occurred more slowly compared to in vivo. Such developmental retardation was milder in the lower limbs than in the upper limbs. In horizons XIV through XVIII, the limbs cultured for longer period than four days showed developmental dissociation of mesenchymal tissues, i.e., the maturation of cartilage advanced more than did the development of other tissues of the limb. The time lapse between the curettage and the culture ranged from 1.5 hours to seven days, but this had no close relationship with the occurrence of degenerative changes. Comparing the data obtained here with the corresponding results of a similar study in mice, it was concluded that the differentiation of the human limb occurs far slower than the mouse limb and shows some different patterns. These results suggest that it is possible to study in vitro comparison of effects of some teratogens on human and mouse limbs.
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  • 114
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 625-629 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Single spermatozoa and spermatozoa in rouleaux were found throughout the genital tract of 21 female guinea pigs killed 15 minutes to 24 hours after copulation. Three females killed three to five minutes postcopulation had single spermatozoa and spermatozoa in rouleaux in the vagini, cervix, and uterus but not in the oviduct. The number of rouleaux and the number of spermatozoa in individual rouleaux decreased after copulation in all parts of the female genital tract with time while a corresponding increase in single spermatozoa was evident. The rate of rouleaux dissociation was faster in uteri than in oviducts. Only single spermatozoa were found near ova in the oviducts. The uterotubal junction appeared to act as a barrier to multitudes of spermatozoa passing from the uterus to the oviducts. However, some single spermatozoa and some rouleaux passed this barrier. Unusually large rouleaux were observed up to 12 hours after copulation in the pockets of the uterotubal junction. Single spermatozoa and few rouleaux of two spermatozoa in the uteri of females killed 8 to 24 hours postcopulation were phagocytised. No phagocytosis of spermatozoa was observed at any time in the oviduct.
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  • 115
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The monkey Sertoli cell, a tall columnar cell, extends from the basement membrane of the seminiferous epithelium to the tubule lumen. Its nucleus occupies a basal position and reveals extensive nuclear envelope infoldings. A zone of fine filaments, approximately 0.5 μ in thickness, invests the nucleus and appears to prevent other cell organelles from approaching it. The basal cytoplasm is characterized by numerous mitochondria and abundant smooth endoplasmic reticulum. Lipid droplets, 3 to 4 μ in diameter, membrane-limited dense bodies of various shapes and densities, Golgi cisternae, scattered free ribosomes and parallel profiles of rough endoplasmic reticulum are common. The more apical portions of the cell contain longitudinally oriented microtubules and rod-shaped mitochondria, but other organelles are rare.The seminiferous tubules of monkeys are surrounded by three to five circumferentially arranged cells that overlap each other but are separated by intercellular spaces of at least 300 to 400 Å. Tracers such as horseradish peroxidase and lanthanum nitrate injected intravascularly readily pass between the peritubular cells and enter the germinal epithelium. Within the epithelium the tracers outline the spermatogonia and early spermatocytes by permeating the surrounding intercellular spaces. Further penetration toward the tubule lumen is effectively prevented by the occluding tight junctions joining adjacent Sertoli cells. Thus, in monkeys the peritubular epithelioid cells do not impede vascularly introduced tracers from penetrating into the germinal epithelium. The only morphological component of the blood-testis barrier in the macaque appears to be the Sertoli-Sertoli occluding junction.
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  • 116
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 725-735 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The day-by-day developmental changes which occur in the respiratory system, mesenteries and celom of the sheep embryo from 14 to 34 days coital age are documented chronologically and described. This work provides standards of normal development which can be used as a basis for future work on abnormal development of these structures.The respiratory diverticulum which first appears on the seventeenth day is seen as a primitive lung bud on the nineteenth day and becomes bilobed on day 20. By the twenty-first day a laryngotracheal tube is present and the larynx develops in the next ten days.The dorsal mesogastrium forms on the eighteenth day and the omental bursa is seen as an invagination by the twenty-first day. A splenic primordium associated with the omentum is present by the twenty-seventh day.The dorsal mesentery appears on the eighteenth day and undergoes torsion, herniation and coiling on the twentieth, twenty-second and twenty-seventh days. The ventral mesentery is present on the seventeenth day but disappears centrally between the eighteenth and twenty-first days.An extraembryonic celom is seen on the fourteenth day and the formation of the intraembryonic celom occurs on day 15. Development of the pleuroperitoneal membranes commences on the twenty-first day. Complete separation of pericardial and pleural cavities is completed by the twenty-eighth day.
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  • 117
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973), S. 35-47 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: After administration of 5-hydroxydopamine, one of the “false” adrenergic transmitters, core materials within both large and small vesicles of the adrenergic nerves increase in density, while clear vesicles in the cholinergic nerves do not change. In the vas deferens of the mouse, initial sign of the uptake is seen as early as one minute after intravenous administration. Eighty to ninety percent of vesicles in the adrenergic nerve varicosities are filled with dense cores by more than 100 mg/kg of 5-OH-DA administration. 5-OH-DA stored in the vesicles remains for seven to ten days and gradually disappears thereafter. After administration of 5-OH-DA, acetylcholinesterase (AChE) activity is examined in the nerve varicosities in the atrium. AChE activity in the adrenergic nerve fibers is discussed in the light of these findings.
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  • 118
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Intranuclear annulate lamellae were initially observed on day 9 of gestation. They increased in frequency until day 12, after which a decline in frequency was noted. Numerous IAL were in close association with nucleoli on days 11 and 12 and numerous large dilatations of the intermembranous space were present. IAL were also associated with cytoplasmic invaginations and inclusions of the nucleus. The frequency of invaginations and inclusions also increased from day 9 to 12 and brought increased amounts of cytoplasm into contact with the nucleus. Continuity of the intermembranous space of the IAL with the perinuclear space and the latter with the cisterns of rough endoplasmic reticulum suggested a possible route for nuclear-cytoplasmic exchange in either direction.
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  • 119
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 120
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: To clear up indecision and disparities in the literature of muscular functions in the cheek and lips, multichannel electromyography with fine-wire intramuscular electrodes was used in eight subjects. Both facial expressions and musical performance were investigated. Intersubject variations were common in the various muscles and intrasubject variation also appeared. The production of specific notes at specific volume on the trumpet or trombone did not depend on exact patterns of activity in the muscles of the lips and buccinator. Gentle puffing out of the cheek produces little or no activity in any muscle, but when this is done forcefully the orbicularis oris activity is marked. Buccinator can be kept deliberately relaxed or active during puffing. Smiling always produces buccinator activity as does forceful retraction of the corners of the mouth. Levator anguli oris activity always recruits concurrent buccinator activity but the reverse is not true.
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  • 121
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In the rat, autotransplanted minced skeletal muscle undergoes degenerative changes prior to the regeneration of a whole muscle. In this study, both the degenerative and early regenerative processes were examined using histochemical procedures for the localization of glycogen, neutral lipid, phosphorylase, lactate dehydrogenase, cytochrome oxidase, glucose-6-phosphate dehydrogenase and non-specific esterases. Glycogen and phosphorylase activity disappeared in all muscle fibers within 24 hours after mincing. Vascular injections of ink demonstrated that during the second to tenth days after mincing a central ischemic zone of degenerating minced muscle was surrounded by a vascularized zone of regenerating muscle. Lactate dehydrogenase staining persisted during the first week in the degenerating muscle fragments of the central zone. This latter histochemical observation was supported by quantitative evidence which showed that degenerating muscle isolated from the central zone of four day regenerates produced lactic acid in the presence of glucose. Cytochrome oxidase activity decreased rapidly in the degenerating muscle while succinic dehydrogenase persisted somewhat longer. Although non-specific esterases and glucose-6-phosphate dehydrogenase activities were not significant in normal muscle, they were histochemically detectable in degenerating muscle during the first week. The capacity for anaerobic metabolism apparently persists in the degenerating minced muscle for several days; this energy source may be sufficient to maintain the myogenic cells in an environment of degeneration and ischemia until they become reassociated with a vascular supply.
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  • 122
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 176 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 123
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Although it has been established that human enamel mineralization follows the incremental pattern of matrix secretion, microradiographic studies of rodent enamel still support a non-incremental pattern of mineralization. This study examines the mineralization sequence using microradiography, as well as measurement of crystal size and distribution on electron micrographs of the various regions of rat incisor enamel. The microradiographic density pattern was found to correlate with the major regions of structural variation within the enamel. Measurement of crystals revealed a rather uniform positive gradation in their size from the surface to the dentino-enamel junction, i.e., crystal size was found to be directly related to crystal age. Crystal distribution analysis demonstrated that an inner region of enamel contains a much larger volume of crystal-free space than other areas. This is the same region which has been described as being out of step with an incremental pattern of mineralization, in that it is less dense than enamel either superficial or deep to it. It is concluded that mineral accretion follows the same incremental pattern in the rat incisor as in humans and that the misleading microradiographic image merely reflects a non-homogeneous distribution of crystals.
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  • 124
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This investigation was undertaken to help fulfill the practical need of the rhinologic surgeon for a more accurate anatomical knowledge of the cartilages of the nasal tip.Four adult caucasian noses aged 62-88 years were embedded en bloc and serially sectioned. The nasal cartilages of one were reconstructed in wax. Anatomical relationships of the lateral nasal cartilage to the lateral crus of the greater alar cartilage were compared. The findings were compared with descriptions found in the literature.The lateral nasal cartilage curls to varying degrees laterally and upward on its inferior margin where it underrides the lateral crus of the greater alar cartilage. The curl is greater anteriorly and diminishes postero-laterally to the point where the cartilage lies flat. The lateral crus of the greater alar cartilage also may curl medially and downwards on its superior margin where it overrides the lateral nasal cartilage. Sesamoid cartilages are present in all specimens.These findings, although known to many rhinologic surgeons, are not clearly established in the literature.
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  • 125
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    The @Anatomical Record 177 (1973), S. 427-439 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Immersion of Rana pretiosa tadpole tail integument in 1 μg/ml of cytochalasin B (CCB) for 45 minutes disrupted various cell structures of the two-squamous cell-layered epidermis including macromolecular components within microvilli and subjacent to the apical plasmalemma, the unit membrane which bounds mucinogenic vesicles and various other supranuclear structures. Surface cells exhibited the greatest degree of organelle disorganization when pieces of excised tail fin (“discs”) were treated with the antibiotic. This may indicate a differential response to the drug by various regions of the cytoplasm or that the concentration of CCB and/or exposure period was only adequate to penetrate the most superficial layers of this epithelium. The effect(s) of the penetrate the most superficial layers of this epithelium. The effect(s) of the antibiotic on filaments and filament related kinetic processes is discussed and the possibility of dissimilarities in CCB-sensitivity between immature and differentiated plasmalemma and among unit membrane of various organelles is considered.
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  • 126
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    The @Anatomical Record 177 (1973), S. 461-463 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fact that the inferior rectal nerve may have an independent origin from the sacral plexus is acknowledged in most current anatomy texts. That it may pierce the sacrospinous ligament well medial to the ischial spine is no longer mentioned. This variation which may occur in as many as 20% of the sides examined, could present a problem in pudendal block.
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  • 127
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973), S. 441-459 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultimobranchial bodies of the chick consisted of follicles and cell cords. The follicles were of various sizes and shapes. Their epithelium was simple or stratified, squamous to cuboidal, and contained two cell types. The lumen-bordering cells had microvilli at their apex, a few long, flat ergastoplasmic sacs, a prominent Golgi, an extensive system of smooth membrane tubules and microvesicles, abundant free ribosomes, no granules and indented nuclei. Their lateral membranes followed a sinuous path and their membrane at the base showed occasional intense pinocytotic activity. Thus these cells appear well differentiated and functionally active, whatever their function may be. The second cell type, never in contact with the lumen, also differed by its abundant granules, the smooth path of its plasma membrane, the smooth outline of its nucleus and the occasional presence of intranuclear vesicles. The cell cords were made essentially of these same granular cells. It was shown histoimmunologically that numerous calcitonin-containing cells were present in the cell cords; those few present within the wall of the vesicles never bordered on the lumen. It is concluded that the granular cells are producing calcitonin, while the lumen-bordering cells contribute the holocrine secretion of the vesicle.
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  • 128
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Using bipolar fine-wire electrodes, we examined the right and left longus colli (LC) and sternocleidomastoideus (StM) muscles electromyographically in ten healthy young adults. Action potentials were recorded on FM magnetic tape and each experiment was also videotaped. The head-neck motions were recorded using a special neck goniometer. The muscles were studied in sitting, supine, prone and lateral positions, both during free movements and against resistance. There was complete inactivity in both muscles in relaxed sitting, normal breathing, deep expiration, and wet and dry swallowing. There was very marked synchronous EMG activity of the LC and StM muscles during resisted forward flexion, marked activity during neck flexion against head weight in the supine position, and during resisted right and left side-bending. Variable activity was found in both muscles during deep breathing, coughing, forceful blowing, loading on top of the head, resisted backward extension, neck holding against head weight in the prone position and in twisting movements downwards and upwards. During free flexion-extension movements, LC and StM act synchronously. During free lateral bending they work homolaterally, but during free rotation to the right, the right LC works with the left StM and vice versa.
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  • 129
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    The @Anatomical Record 177 (1973), S. 549-559 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: There are two types of granular glands in the skin of leopard frogs (Rana pipiens). Cellular glands produce fine intracellular granules rich in carbohydrate, carboxylic acids, tyrosine and sulfur-containing amino acids. Luminal glands consist of peripherally located nuclei with scant cytoplasm. Fine granular material in these glands resembles cellular gland secretion, except that the carbohydrate is less susceptible to periodate oxidation and that a diphenol (DOPA?) is present instead of tyrosine. The prominent lumen contains large granules composed of phospholipoprotein, and are also rich in primary catecholamine and a sulfur-containing amino acid. There was no evidence of 5-hydroxy-tryptamine or steroids.
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  • 130
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    The @Anatomical Record 177 (1973), S. 485-501 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Light and electron microscopic examination of tissues fixed in situ by perfusion of the gravid horn of the uteri of mares between 36 and 38 days of gestation revealed that the equine endometrial cups are composed of trophoblast cells which originate from the discrete annulate portion of the foetal membranes known as the chorionic girdle. This structure consists of closely opposed villous projections of elongated trophoblast cells and it becomes firmly attached to the endometrium around the thirty-sixth day of pregnancy. The specialized girdle cells invade and phagocytose the endometrial epithelium and then migrate through the basal lamina into the endometrial stroma where they develop into endometrial cup cells.
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  • 131
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Multivesicular bodies and related structures of the syncytiotrophoblast of human term placenta have been studied ultrastructurally and cytochemically. Circular profiles of vesicles termed pre-multivesicular bodies (pre-mvb's) were observed often near Golgi complexes. Multivesicular bodies (mvb's) with electron lucent matrices (L-mvb's), mvb's with electron dense matrices (D-mvb's), and dense bodies were also prevalent organelles of the syncytium. These organelles all exhibited dialyzed iron reactivity and staining characteristics suggesting that the organelles were related. Material within Golgi saccules, Golgi vesicles, vesicles of pre-mvb's, and vesicles of mvb's were all reactive with osmium zinc iodide (PZI). This OZI reactivity further indicated a relationship between the organelles. The matrix of the mvb's exhibited variable reactivity for acid phosphatase (AcPase) but such activity was not encountered in Golgi elements of syncytiotrophoblast. It is suggested that the mvb's of human term placental syncytium are likely formed by aggregation of vesicles of Golgi origin into pre-mvb's, that the pre-mvb's are then capable of transforming into L-mvb's, D-mvb's, and finally into dense (residual) bodies. It is also suggested that mvb's may function in the selective hydrolysis and transport of endocytosed proteins, including globulins. Additional bodies with intense acid phosphatase activity were designated elongate bodies. Other Distinctive organelles designated dense cored spheroids were occasionally observed in the syncytioplasm.
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  • 132
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    The @Anatomical Record 175 (1973), S. 87-96 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Standard tissue culture and epithelio-mesenchymal separation and recombination techniques were applied to the question of sex determination of the male urogenital sinus of embryonic mice. Explants of urogenital sinuses from 12- to 17-day old embryos were cultured in an androgen-free environment to a gestational age equivalency of 18 to 20 days. The developmental response of these explants led to the following conclusions: (1) Androgens are necessary for initiation of prostatic bud outgrowth; (2) The effect of androgens can be demonstrated at the stage when the fetal testis begins to secrete androgens; and (3) Prior to the appearance of prostatic buds, the urogenital sinus has the capacity to pursue that developmental end-point independently of further androgen stimulation. In addition, the developmental response of recombinants composed of androgen-treated and untreated epithelium and mesenchyme from the urogenital sinus has shown that it is the epithelium which is primarily determined by androgens during prostatic morphogenesis.
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  • 133
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    The @Anatomical Record 175 (1973), S. 127-138 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study gives a quantitative description of hypoglossal neurons in the common boa, Constrictor constrictor. In this animal the hypoglossal nuclei are spatially distinct from the ventral horns and do not contain subnuclei. They contain a mean ± S.D. of 942 ± 162 neurons, many of which have double nucleoli. The neurons are shaped like prolate ellipsoids which are oriented with their long axes perpendicular to the ventricle. An average hypoglossal neuron has a major axis of 21.8 μ and a minor axis of 19.6 μ. Although neurons show a considerable range of sizes, neurons of different sizes are not segregated into different regions of the nucleus. Developmental differences in the size, distribution in the medulla, and the percentage of doubly nucleolated neurons occur, but the shape and orientation of hypoglossal neurons do not vary with age.
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  • 134
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructural pathology of the initial segment of the rat caput epididymidis was examined after oral administration of a single high dose of the antifertility compound α-chlorhydrin (U-5897) at time intervals ranging from two hours to nine days after treatment. At doses in excess of 30 mg/kg this compound produces a lesion specifically localized in the initial segment of the epididymis characterized by sloughing of the epithelium, which leads to obstruction of the lumen of the epididymal duct, spermatocoel and sperm granuloma formation and an ultimate occlusive fibrosis. In rats fed 140 mg/kg of U-5897 the first effects can be seen as early as two hours after treatment. Within 48 hours after treatment, the lumen of the greater part of the initial segment is filled with degenerating cells and debris which block further passage of sperm along the duct. The present study provides insight into the nature of the early events in the evolution of this epididymal lesion. Possible mechanisms of action of α-chlorhydrin are discussed.
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  • 135
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The uptake and turnover of 3H-uridine by periosteal and endosteal osteoblasts were assessed autoradiographically. Five-week old mice were injected with 5 m̈CI of 3H-uridine (Sp. Act. 21 Ci/mM) per gram of body weight and killed at intervals varying from 15 minutes to one month post-injection. Femora were processed histologically and autoradiographs were prepared from 5 m̈m decalcified sections exposed for 36 days. Autoradiographic grains were counted over the nucleus and the cytoplasm of 600 periosteal and 600 endosteal osteoblasts per time period. 3H-Uridine was initially rapidly incorporated into the nucleus attaining peak activity one hour after injection. Incorporation of label into cytoplasmic RNA was maximum at one to two days. At one month grain counts were at minimum values. The loss was more gradual from the nucleus than from the cytoplasm. At earlier time periods the nucleus showed a higher label than the cytoplasm. At 8 to 16 hours the label was evenly distributed and at later time periods the cytoplasm exhibited a higher grain count. Dia-physeal periosteal osteoblasts and metaphyseal endosteal osteoblasts differed in both the quantity of label and the rate of utilization. Endosteal cells exhibited almost twice the activity. RNA biosynthesis appears to be significantly higher in endosteal cells than periosteal cells thus reflecting differences in protein synthesis by these two cell compartments.
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  • 136
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    The @Anatomical Record 175 (1973), S. 529-537 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The presence of β-lipotrophin or an immunologically similar substance was demonstrated in the intermediate lobe cells and some basophils of the anterior lobe by both fluorescent and peroxidase-conjugated antibody methods. These basophils were found to be corticotrophs, i.e., reactive with anti-ACTH. ACTH, when added to anti-β-LPH, decreased the fluorescence and peroxidase reactions of intermediate lobe cells and the anterior lobe corticotrophs. The addition of MSH to anti-β-LPH produced a slight decrease in the reaction between the intermediate lobe cells and anti-β-LPH. The intermediate lobe cells also reacted with anti-ACTH. Both Somatotrophs and lactotrophs reacted with anti-β-LPH to give positive fluorescence or peroxidase reactions. However, the addition of STH to anti-β-LPH abolished the reaction between anti-β-LPH and somatotrophs. Similarly, LTH, when added to anti-β-LPH, abolished the positive reaction of lactotrophs to anti-β-LPH. When STH, LTH and ACTH were added to anti-β-LPH, the fluorescence of the somatotrophs and lactotrophs was abolished, whereas the corticotrophs maintained their fluorescence at a reduced intensity. These results indicate that the somatotrophs and lactotrophs do not contain β-LPH and that corticotrophs contain β-LPH.
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  • 137
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    The @Anatomical Record 175 (1973), S. 607-623 
    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 adrenal gland is described at full-term (day 22) and during artificially prolonged gestation (days 23, 24, 25). The latter was achieved by daily subcutaneous injections of seven mg progesterone to gravid females from the twentieth through the twenty-fourth day. Cortical and medullary cells contained well developed organelles at all stages. Nonetheless, zonation of the gland was not yet distinct. Whereas the zona glomerulosa and zona fasciculata were fairly well delineated, the zona reticularis and medulla were as yet poorly defined. The latter regions were intermingled, and thus collectively referred to as the “zona reticulo-medullaris.”During prolonged gestation (days 24 and 25 only), many cells of the zona fasciculata and zona reticulo-medullaris contained dilated smooth endoplasmic reticulum and numerous enlarged mitochondria. Enlarged mitochondria were observed also in medullary cells concurrent with a paucity of catecholamine storage granules. Moreover, meconium staining, which is indicative of fetal stress, was also observed on days 24 and 25. The ultrastructural changes observed were interpreted to be an expression of response by the fetal adrenal gland to fetal stress produced by as yet undetermined factors arising during prolonged gestation.
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  • 138
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    The @Anatomical Record 176 (1973), S. 129-141 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Acute inflammatory exudates which are induced by the intra-peritoneal injection of sheep red blood cells contain a variety of connective tissue cell types. Granulocytes, macrophages and lymphocytes constitute the vast majority of the exudate cells. The peritoneal macrophages are principally involved in the phagocytosis and clearance of the whole SRBC from the peritoneal cavity. The exudate lymphocytes which accumulate during the first 24 hours are derived from a pool with a fast turnover rate and are newly formed. While these lymphocytes undergo an enlargement and increase their basophilic cytoplasm during this response, they fail to show increases in their DNA synthesis while in the inflammatory exudate.
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  • 139
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Nucleation sites for mineralization in rat distal femoral epiphyseal cartilage were studied with the electron microscope. Normal, low-phosphate, vitamin D deficient rachitic, and healing rachitic rats were used.The earliest ultrastructural evidence of mineralization in normal animals was the appearance of crystallites inside extracellular matrix vesicles, located in the longitudinal septa of the maturing cell zone in the epiphyseal apparatus. The crystallites were absent throughout the entire hypertrophic cell zone of the rachitic specimens.The first evidence of mineralization in rachitic animals treated with both phosphate and vitamin D was the presence of crystallites in the extracellular matrix vesicles. These were located in the longitudinal septa of the lower hypertrophic cell zone, near the capillary tufts of the primary spongiosa. Crystallites were first detected by 12 hours after treatment; by 24 to 48 hours, the number of matrix vesicles containing crystallites increased substantially.Treatment of rachitic animals with phosphate alone effected the same results as phosphate and vitamin D combined. Rachitic animals receiving vitamin D alone did not form mineral in the time periods studied.The results of this investigation support the view that the deposition of mineral in mammalian cartilage requires nucleation sites in the extracellular matrix. The findings also are consistent with the hypothesis that membrane-bounded, extracellular matrix vesicles contain the initiating system for calcification of the rat epiphyseal apparatus.
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  • 140
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A technique for obtaining accurate casts of the bronchial tree and alveolar region is presented and several of the uncertainties involved in bronchial tree casting are discussed. Tompsett's basic casting technique is modified to use silicone rubber; supportive trays and a shape-preserving gelatine injection are eliminated by suspending the lungs in a water bath. Fresh or frozen lungs may be used and prior fixation is not necessary. No elaborate apparatus, beyond usual laboratory items, is required. The slow, low pressure injection of rubber into the bronchial tree minimizes overdistension due to high translumenal pressures. The resulting cast is flexible and durable. Linear shrinkage is minimal with resulting volumetric errors of less than 2%. If desired, one may simultaneously inject the pulmonary arterial and venous systems with colored rubber, yielding a cast of greater educational utility.
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  • 141
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    The @Anatomical Record 176 (1973), S. 307-319 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Marmoset placentas were obtained surgically from early, mid and late pregnancy and examined with the electron microscope. At each stage both inner cytotrophoblastic and outer syncytiotrophoblastic layers were identified at the surfaces of the labyrinthine trabeculae. The trabecular cores contain very little connective tissue and are made up primarily of allantoic blood vessels of the peripheral umbilical circulation. Although a subepithelial basal lamina consistently is seen underlying the trophoblast, no subendothelial basal lamina has been identified at any stage. In early stages, the cytotrophoblast cells form a contiguous layer; consequently, the syncytium does not reach the basal lamina; and the placental membrane is hemodichorial. In the latest stage, since cytotrophoblast, though present, forms an interrupted layer and syncytiotrophoblast reaches the lamina, the membrane properly can be considered hemomonochorial. Not only in the gradual reduction in numbers of cytotrophoblast cells, but also in the fine structure of each constituent cellular layer, the membrane of this primitive anthropoid is strikingly like that of higher primates.
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  • 142
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The owl monkey (Aotes trivirgatus) differs from most primates in being nocturnal in habit and having primarily scotopic vision. Photoreceptor cells of the retina of this species were studied with the electron microscope and compared with corresponding cells of other primates. No striking qualitative differences were noted. Most of the receptors are typical rods, but approximately 5% are cones, based on the following features: shorter, tapering outer segments, discs with smooth rather than scalloped margins and with uniformly narrow internal spaces, the membranes of which in some cases are continuous with the plasma membrane; broad inner segments with numerous mitochondria; nuclei that lie immediately against the outer Junctional zone (outer limiting membrane) with relatively thick inner fibers leading to large pedicles in the floor of which are numerous typical “synaptic triads.” One relatively unusual feature of the rods is the prominence of the striated rootlets associated with the basal bodies of the cilium-like connecting pieces. An apparently intimate relation of the rootlets to investing mitochondria, especially to their tubular internal cristae, is discussed with regard to the possibility of a function for the rootlet other than static anchoring of the cilium.
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  • 143
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    The @Anatomical Record 176 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 144
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    The @Anatomical Record 176 (1973), S. 49-64 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Embryonic chicks were treated with exogenous L-thyroxine or with thiourea at eight days of incubation and the subsequent development of the tibia studied.The weight of the tibia was 62% lower than that from normal embryos, and the length of the tibia 24% below normal in the embryos treated with thiourea. This reduced rate of growth was shown to be due to a reduction in the rate of maturation of chondroblasts into chondrocytes, reduced chondrocyte hypertrophy and defective deposition of acid mucopolysaccharide into the cartilage matrix. Osteogenesis per se was unaffected. It was concluded that thyroxine plays a role in the control of chondrocyte maturation and in cartilage matrix production during normal development.The epiphyses of the tibiae from the embryos treated with thiourea were extensively eroded, invaded by marrow and more fragile than those from untreated embryos, indicating that thyroxine is essential for the maintenance of the integrity of the articular cartilage. An abnormal core of bone developed within the proximal epiphysis of these embryos.Exogenous thyroxine at concentrations as low as 100 pg/embryo also reduced the growth of the tibia below that seen in untreated embryos. Evidently the cells of the skeleton are sensitive to both lowered and increased levels of circulating thyroxine.
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  • 145
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    The @Anatomical Record 175 (1973) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 146
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Light and electron microscopic analysis of adenovirus-infused ileal loops disclosed virus particles within the tubulo-vacuolar apparatus of absorptive cells. Tissue observed from five-minute loops contained virus particles largely within apical tubules and vesicular profiles. Similar particles were observed within cisternae and supranuclear vacuoles as well as within apical tubules in tissue samples from 10- and 15-minute loops. Loops maintained for 30 minutes demonstrated virions predominantly in the supranuclear vacuole of each absorptive cell. In no instance was a virion seen free within the cytoplasm or nucleus and none was apparent elsewhere in the mucosa. It appears that absorptive cells of the ileum are capable of sequestering exogenous virions and conveying them to established lysosomal bodies in the supranuclear cytoplasm. Here they may be either stored or degraded, thus impeding their progress to other intra- or extracellular locations. The possible significance of these findings is discussed in detail, and it is proposed that sequestration of ingested virions by the tubulo-vacuolar apparatus of the ileal absorptive cell may serve some protective function in the developing neonate. It is suggested that direct infusion of “purified” virus into intestinal loop preparations is an efficient means of observing virus-intestinal cell interactions in the living animal. This experimental model might prove effective in future studies of viral infection in the intestine, particularly if it is combined with both serological and morphological methods.
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  • 147
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 148
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The third ventricular walls and floor of male and female mink (Mustela vison) were analyzed with comparative light microscopy, transmission and scanning electron microscopy. Distinct regional fine structural variations were noted in the appearance of the dorsal, middle third and lower portions of the ventricular wall and floor. These variations were characterized by an abrupt decrease in the density of ciliated ependymal surfaces in the middle one-third of the ventricular wall. The ventral walls and floor of the lateral and infundibular recesses displayed smoother contours with numerous bleb-like protrusions and blunt villiform processes. Occasionally multipolar neuron-like cells were observed to lie upon the floor of the infundibular recess. Speculation is raised relative to the differing functional capacities of these various ventricular areas.
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  • 149
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Feeding rats a high-sucrose, fat-free diet after two days of starvation resulted in an initial accumulation of hepatic lipid and an increased activity of those enzymes which catalyze and support the formation of fatty acids from acetyl precursors. Rats starved for 48 hours were refed a high-carbohydrate, fat-free diet for 1, 2, 3, 5, 7 and 14 days. Frozen sections of liver were stained with Oil Red O for lipids. In adjacent sections glucose-6-phosphate dehydrogenase (GDH)and malate enzyme (ME) were localized and the relative enzyme activity evaluated. Enlargement and yellowing of the liver were noted after two to three days feeding of the fat-free diet, but subsequently the liver appeared normal. Oil Red O staining demonstrated a progressive accumulation of lipid from the periportal to the centrilobular area during the first three days of refeeding. After the seventh day on the fat-free diet, however, the lipid accumulation was less and the distribution appeared similar to that of animals maintained on a balanced diet. A marked increase in both GDH and ME activity was noted throughout the liver lobule after two days on the fat-free diet. Enzyme activity remained high throughout the lobule during the balance of the experimental period, with maximum activity in the centrilobular area.
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  • 150
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    The @Anatomical Record 176 (1973), S. 329-332 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cerebral and dural venous systems are derived from separate layers of the vascular plexus that cover the brain in early embryonic life. The cerebral veins arise from the inner layer of the plexus which invests the neural tube and join the dural systems in the superior midline concomitant with the development of the sinuses. The dural veins, the lateral lacunae and the dural sinuses arise from the outer embryonic plexus. In the fully developed human these two systems are separate except for an occasional communication between a lateral lacuna and a superior cerebral vein just before the vein joins the superior sagittal sinus. The lateral lacunae are a distinct anatomical entity and their venous meshwork is to be regarded as a part of the dural venous system.
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  • 151
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 152
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    The @Anatomical Record 176 (1973), S. 405-419 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Morphological changes in the secretory cells of the convoluted granular tubules of the rat submandibular gland were studied following the stimulation of salivary secretion with pilocarpine nitrate. The mechanism of synthesis of secretory protein by these cells is controversial and this study was undertaken to help elucidate this mechanism. It was found that the cells expelled the contents of their secretory granules in the typical exocrine fashion. Shortly after secretion, increased volumes of rough endoplasmic reticulum appeared in the cytoplasm. The endoplasmic reticulum underwent a sequence of morphologic changes and disappeared from the cytoplasm as the secretory products were restored. Additionally, the Golgi complex showed changes. The results of this study indicate that the secretory cells of these tubules follow the accepted exocrine pattern of secretory production and discharge and that they synthesize exportable proteins at a rate far below that of other exocrine systems. The relationship of these findings to the observation that under non-stimulated conditions the cytoplasm of these cells lacks some of the organelles which are normally associated with exocrine type protein production is discussed.
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  • 153
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    The @Anatomical Record 175 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 154
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    The @Anatomical Record 175 (1973), S. 539-559 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The protein tracers, horseradish peroxidase and ferritin, are demonstrable in the subzonal space of all preimplantation stages within ten minutes when incubated in vivo or in vitro. However, there is very little uptake of these proteins by ova and two-cell stages. By the blastocyst stage there is greatly increased uptake of exogenous protein. The proteins appear in coated micropinocytotic vesicles and tubules, larger vacuoles, and more complex bodies. Blastocysts from the period of lactationally delayed implantation show an even greater amount of uptake, especially in the supranuclear region. Peroxidase reaction product can be demonstrated in the cavity of day 5 blastocysts in 30 minutes, and in the cavity and basal lamina of the blastocysts during delayed implantation in ten minutes. Ferritin was more sparsely distributed, and was not seen in the blastocyst cavity in any of the time periods. Peroxidase is apparently transported via an intracellular pathway, since it is not seen in the elaborate intercellular spaces between trophoblast cells. Acid phosphatase activity is demonstrable in vacuoles, dense bodies and Golgi cisternae in all stages, indicating that the potential for degradation of ooplasm and phagocytized material by a lysosomal system is present in all of the preimplantation stages examined.
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  • 155
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The purpose of this investigation was to study the nerves in mouse molar teeth during their development to observe their distribution and their relationship to the odontoblast and its process. The specimens were first assessed by light microscopy using silver staining techniques. It was found that by nine days after birth, major nerves appeared in the pulp organ and extended to the basal region of the odontoblasts. At 15 days, a subodontoblastic neural plexus had developed, and by 25 days, isolated nerves penetrated into the predentin of the pulpal horns. From 25-70 days, a highly organized subodontoblastic plexus was apparent with branches extending into the odontoblastic layer, predentin and inner dentin.Ultrastructural study revealed small, nonmyelinated nerves at the basal region of the odontoblasts by nine days. Both myelinated and small, nonmyelinated nerves appeared in the subodontoblastic plexus. Small nerves closely associated with the odontoblastic process were found within the predentinal tubules by 25 days. These processes contained occasional mitochondria, numerous microvesicles and small dark granules. From 35-50 days of age, similar nerves which exhibited alternate constrictions and dilations along their lengths were found in the tubules of circumpulpal dentin. By 60 days, both Schwann cell covered and naked axons appeared among the odontoblasts, and by 70 days Schwann cell covered axons appeared in predentin.
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  • 156
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    The @Anatomical Record 175 (1973), S. 657-671 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Human embryonic hand and foot plates (horizon XVI) exhibit localized differences in mitotic activity between developing digital and interdigital zones of mesenchyme. To investigate development of regulation of cell reproduction, mesenchymal cells from lower limb buds dissected from a human embryo (stage XV) were cultured. Electron microscopy reveals that HLM15 cells in situ are fibroblastic, exhibit euchromatic nuclei, one to two peripheral nucleoli, extensive granular ER, free ribosomes, and microfilaments and microtubules oriented in the long axis of cellular processes. Cells released from substratum with trypsin-EDTA become rounded and microfilaments and microtubules become disoriented, perinuclear bundles. HLM15 has a mean generation time of 24 hours during logarithmic growth and karyotype analysis indicates that cells retain diploid chromosomal number after 17 passages. DNA-fluorochrome analysis on the Los Alamos Flow Microfluorometer (FMF) demonstrates that HLM15 cells possess no detectable polyploidy. Computer fit of FMF distributions reveal that random populations of HLM15 during exponential growth contain 42.6% cells in G1, 45.9% in S and 11.5% in G2+M. As confluency is reached these data become 57.6%, 37.5% and 4.9% respectively. Disaggregated limb mesenchyme (in vivo) analyzed without culturing exhibit FMF distributions of 56.1% in G1, 36.7% in S and 7.2% in G2+M. Similarities in cell cycles between near-confluent HLM15 cultures and limb mesenchyme in vivo suggest that regulation can be achieved by increasing or decreasing the traverse time through G1 (both in vitro and in vivo). The proportion of non-cycling cells (G0) in the FMF G1 distribution is presently not known.
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  • 157
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    The @Anatomical Record 175 (1973), S. 707-723 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Corpora lutea from one recently post-partum and six pregnant African elephants (Loxodonta africana) were fixed for electron microscopy. Progesterone concentration was determined for five of these corpora lutea utilizing the competitive protein binding technique.Lutein cell size and progesterone concentration increased from one and two months of pregnancy to a maximum at three months (P 〈 0.01). After eight months of pregnancy, lutein cell size decreased to two-month values and luteal progesterone was similar to the one-month level. Lutein progesterone was very low in a recently post-partum animal and lutein cell size was minimum. Maximum lutein progesterone was 4.1 ng/mg, much lower than that reported for other mammals.Lutein cell fine structure exhibited characteristics typical of lutein cells from other species but with some variation. Unusual features include peripheral distribution of organelles, large stores of lipid and lipofuscin throughout pregnancy, and mitochondria sparsely populated with lamellar cristae. The data indicate that the corpus luteum of the African elephant has significant but limited steroidogenic capabilities.
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  • 158
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effect of the administration of p-chlorophenylalanine on the fine structure of the ventricular cardiac muscle of active and hibernating bats was studied. The concentration of norepinephrine in the bat heart was also measured. In the active animal, p-chlorophenylalanine induced a striking increase in the size and number of lipid droplets. Moreover, the lipid droplets exhibited an intimate association with mitochondria. The mitochondria in such associations showed extreme variations in form but exhibited normal arrangement of cristae. p-Chlorophenylalanine also induced a slight increase in the number of glycogen granules but no other effects were apparent. During hibernation, the administration of p-chlorophenylalanine failed to produce a change in either the size or number of lipid droplets. The concentration of norepinephrine in the heart of active and hibernating bats was not altered by the injection of the drug. The present findings indicate that lipid accumulation in ventricular myocardium following injection of drugs is not necessarily the result of depletion of cardiac stores of norepinephrine.
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  • 159
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Thyroid lobes from five common and six White Carneaux pigeons were cut into fragments which were assayed biologically for their calcitonin content. Pooled, alternate tissue slices from the individual thyroid lobes of 18 additional White Carneaux pigeons were assayed; the remaining tissue slices were prepared for light and electron microscopy or for demonstration of histochemical properties associated with the APUD system of polypeptide hormone-producing cells, including: α-glycerophosphate dehydrogenase, acetylcholinesterase, nonspecific cholinesterase, esterase, argyrophilia, and production of fluorogenic monoamines. Calcitonin was present at all cephalo-caudal levels within pigeon thyroid lobes and was concentrated in peripheral, as opposed to central areas of the lobes. White Carneaux left thyroid lobes contained 34-225 MRC U of calcitonin/g tissue. Twelve of 18 right lobes lacked detectable calcitonin; the remaining six lobes contained 12-46 MRC U/g. Microscopy revealed a population of granulated cells that were found only in peripheral regions of lobes containing measurable calcitonin. These cells resemble mammalian thyroid parafollicular cells ultrastructurally. They appear to be surrounded by amine-containing, argyrophilic nerve fibers. Of the histochemical characteristics of mammalian “C” cells tested, only amine-precursor uptake could be correlated with the presence of calcitonin and granulated cells in the thyroid gland of the White Carneaux pigeon.
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  • 160
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    The @Anatomical Record 176 (1973), S. 225-243 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Peripheral nerve fibers close to the sensory neurons of dorsal root ganglia displayed unusually thin myelin sheaths in relation to their axon diameter. Myelinated internodes along each fiber showed large differences in the numbers of myelin lamellae. These fibers are thought to represent spatial progression in degree of myelination as the axon egresses from the nonmyelinated glomerulus to the position of axonal bifurcation. This region is termed the initial complex of dorsal root ganglion cells. While the usual relationship between axon diameter and myelin sheath thickness is seen in the majority of dorsal root ganglion fibers, the fiber comprising each initial complex shows an atypical relationship in that the myelin sheath is unusually thin. Since the pattern of myelination in this small area is incongruous with previous reports attributing the control of myelin sheath thickness solely to axon diameter, the present findings indicate that other, unknown factors are operative in the control of myelination.
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  • 161
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    The @Anatomical Record 177 (1973), S. 1-13 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A population of catecholamine-containing subependymal cells bordering the preoptic recess of the toad hypothalamus was studied by the rapid Golgi method to determine whether the cells have the characteristic contours of neurons or are instead secretory cells similar to peripheral chromaffin cells as proposed in an earlier study. Golgi impregnations of these cells reveal that they possess long basal processes which extend toward the lateral surface of the brain and which are covered with clusters of short projections and longer single projections. The relatively large caliber and rough surface of these processes distinguish them from axonal processes of neurons. Instead the cells closely resemble the ependymal cells bordering the preoptic recess with respect to the lateral course of the basal processes and with respect to the projections on these processes. The only qualitative difference between the ependymal and subependymal cells seen in Golgi preparations is the presence of apical processes projecting from the subependymal cell bodies through the ependymal layer to border on the ventricle. On the basis of this and the earlier study it is concluded that the subependymal cells do not have the characteristics of neurons but instead constitute a new cell type similar to ependymal cells but specialized for the synthesis, storage and secretion of catecholamines.
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  • 162
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    The @Anatomical Record 177 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 163
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    The @Anatomical Record 177 (1973), S. 209-217 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A case of an acardiac human fetus is reported. The unique feature found in this specimen was the remarkably advanced development of the fetus as a whole, but especially of its head and brain.
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  • 164
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Previous work with electron opaque intercellular markers has indicated that in adults occluding junctions between adjacent Sertoli cells are the principal morphological basis of the blood-testis barrier (Dym and Fawcett, '70). Since the barrier of not present at birth this study was undertaken to determine when it is established during postnatal development of the rat and to correlate its appearance with other developmental events in the seminiferous epithelium. From birth to 16 days of age interstitially injected tracers, such as horseradish peroxidase, freely entered the seminiferous epithelium and permeated the 200 Å intercellular clefts between presumptive Sertoli cells and germ cells, reaching the center of the seminiferous cords and site of the future tubule lumen. Between day 16 and 19 occluding junctions between Sertoli cells appear and thenceforth interstitially injected electron opaque tracers were effectively prevented from reaching the tubule lumen. Therefore, in rats, the blood-testis barrier is established between 16 and 19 days of age.In an attempt to determine whether the development of the Sertoli cell junctions and the blood-testis barrier is under hormonal control circulating gonadotropins were suppressed using daily injections of clomiphene or estrogens from birth. The appearance of blood-testis barrier was delayed approximately seven days in the absence of gonadotropins. However, by day 26 the Sertoli cell junctions did appear and interstitially injected tracers were prevented from reaching the tubule lumen. Thus the development of the occluding junctions between Sertoli cells that constitute the permeability barrier does not appear to be directly dependent upon gonadotropins.
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  • 165
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Epidermal melanocytes are easily identifiable in the skin of the Boa Constrictor throughout the whole skin cycle. Intensity of the dopa reaction, however, varies. It is at its peak just before the skin enters its resting phase when the melanization of the beta layer of the epidermis is complete. There is no pigment transfer when those layers of the epidermis are formed which contain alpha keratin. The melanocytes accumulate melanosomes, retain them throughout the resting phase of the epidermis, and donate them again during the subsequent growing period of the epidermal keratinizing system when beta keratin is again formed. Thus, when a new beta layer is formed, most of the melanosomes which are donated to this layer have been formed during a previous cycle. The dermal melanophores do not show morphological or histochemical changes during the shedding cycle of the epidermis.
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  • 166
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    The @Anatomical Record 176 (1973), S. 455-460 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The formation of a third, intermediate, layer of cells in the mouse vaginal epithelium 12 hours after estradiol administration was investigated. Making 3H-thymidine continuously available during the first 12 hours following estradiol administration to spayed mice and killing the treated animals after this period, revealed the intermediate layer of cells as constituted essentially of unlabeled cells. To the contrary, when animals were treated with estradiol 48 or 60 hours following pulse-labeling with 3H-thymidine, and killed 12 hours after hormone injection, autoradiography showed that labeled cells (which were in some part of G1 at the time estradiol was given) become a part of the intermediate cell layer. Grain count distribution in this material confirmed that they do so without undergoing further division. These results support our assumption that the formation of an intermediate layer of cells in the vaginal epithelium of spayed mice within the 12 first hours of estradiol action does not require division of basal cells under the presence of estrogen.
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  • 167
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    The @Anatomical Record 177 (1973), S. 15-22 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Histologic examination of metaphyseal bone of rats intoxicated with elemental phosphorus showed that inhibition of osteocytic osteolysis and chondrolysis account for widening of trabeculae and retention of the chondroid core. These changes are reflected in increased radiographic density and abnormal remodeling.
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  • 168
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    The @Anatomical Record 177 (1973), S. 79-194 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 169
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    The @Anatomical Record 177 (1973), S. 195-207 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The temporal events of cytokinesis were examined with light- and electron-microscopes during first cleavage of the rabbit zygote. When karyokinesis is at the late anaphase-to-early-telophase stage a shallow indentation appears in the vitelline membrane in a plane perpendicular to the spindle. Microvilli are absent in the indentation although present elsewhere. A band of microfilaments is recognizable under the plasma membrane of this region. Sections which pass through the band of microfilaments contain several early mid-bodies located centrally in the egg. In later stages of furrowing the band of filaments is 0.1 μ wide and is circumferentially arranged. These filaments which underlie the broad leading edge of the furrow are 50-80 Å in diameter and are components of the contractile ring. The furrow cavity is filled with blebs of the plasma membrane. The microvilli of the lateral furrow walls interdigitate and “primitive” intermediate junctions develop between the two blastomeres. During late cleavage the stem-bodies fuse into a continuous mid-body which spans two opposite points of the intercellular bridge and fuses with the filaments of the contractile ring.
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  • 170
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    The @Anatomical Record 177 (1973), S. 243-253 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Administration of isoproterenol (IPR), twice daily for five days, to five day old rats resulted in a hypertrophy and hyperplasia of the submandibular gland as indicated by an increase of the total DNA, RNA, and protein contents of the gland. Four different cell types, the acinar cell, the terminal tubule cell, the intercalated duct cell and the striated duct cell were distinguished in 1 μ thick, Epon-embedded sections and their rates of proliferation were estimated from radioautographs prepared following the incorporation of 3H-thymidine. IPR treatment increased both the frequency and the absolute number of the acinar cells as compared to those of control animals. Concomitant with this there was a decrease in the number of terminal tubule cells from 50% in the control to about 15% in the IPR-treated rat submandibular gland. These findings indicate that IPR accelerated the postnatal differentiation and proliferation of acinar cells. Eleven days after withdrawal of the drug the gland showed chemical and morphological evidence of regression of the IPR-induced hypertrophy and hyperplasia and the numbers of acinar cells and terminal tubule cells in the glands of control and IPR-treated rats were the same. Thus the IPR-induced advanced differentiation of the gland was not maintained after the cessation of the IPR-administration.
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  • 171
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    The @Anatomical Record 177 (1973), S. 317-319 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Using an indirect immunofluorescent technique sera from a group of patients suffering from a variety of liver diseases have been shown to contain an antibody which will specifically stain the bile canaliculi of a wide variety of mammals, birds and amphibia. It is suggested that this method is an effective alternative to the methods presently available for demonstration of bile canaliculi.
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  • 172
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: With the use of Golgi-Kopsch and rapid Golgi techniques, seven different neuronal types were described in the nucleus gracilis of the rat. In the caudal part of the nucleus the dendrites were grouped in vertical bundles origented parallel to the collaterals of the fibers in the fasciculus gracilis. Some neurons had dendrites associated with several dendritic bundles separated in the horizontal or parasagittal planes. Two types of interneurons were found in the caudal part of the nucleus. The first had its axon confined within a dendritic column formed in part by its own dendritic arborization. The axon of the second interneuron projected to a nearby dendritic column. In the rostral part of the nucleus, the various neuronal types had dendrites oriented either transversely or along the axis of the nucleus. Fibers from the fasciculus gracilis, at rostral levels, bend to course across the nucleus sending collaterals along the parasagittal plane. Thus the dendrites of the neurons in this region were directed perpendicular and/or parallel to the afferent fibers. Afferent axons to the nucleus gracilis from the pyramidal tract and medullary reticular formation were also described.
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  • 173
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    The @Anatomical Record 177 (1973), S. 393-407 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Unique squamous cells forming one or more layers are invariably present at the inner border of the rat kidney capsule. The cells frequently surround a space or lumen of irregular contour. The cells appear to be supported by collagenous bundles which run between adjacent cells within groove-like indentations in a single cell, but the connective tissue components are separated from the squamous cells by a thick basal lamina. The fibrous capsule is bound to the renal parenchyma by loose connective tissue containing fibrocytes, small collagen bundles, and abundant mononuclear cells which are partially surrounded by processes of the fibrocytes.
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  • 174
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    The @Anatomical Record 175 (1973), S. 737-746 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Guinea pig popliteal lymph nodes were examined by DNA radioassay and radioautography following the selective labeling of tibial and femoral marrow cells by intramyeloid injections of 3H-thymidine. The DNA radioactivity of the node increased for the first four days and at four to seven days exceeded that seen after an intraperitoneal injection of the same total dose of 3H-thymidine, indicating an export of radioactivity from the labeled marrow to the node. Simultaneously, radioautographic sections of the node revealed labeled cells indicative of an origin from marrow precursors. Small lymphocytes constituted 60-90% of the labeled cells and reached maximal numbers at four to six days. Most of them were observed in the cortex, including the subcapsular sinus, primary follicles, mantle zones around germinal centers, and the lumen and walls of post-capillary venules. However, the highest labeling indices of small lymphocytes occurred in the medulla, including the medullary cords, medullary sinuses and efferent lymphatic vessels. Labeled large mononuclear cells, including large lymphoid cells, monocytes and large blast cells, were confined almost exclusively to the cortex. A small number of labeled plasma cells was observed in the medullary cords. It is concluded that newly-formed bone marrow lymphocytes migrate continuously into immunologically quiescent lymph nodes and become widely distributed throughout the cortex and medulla, while some enter the recirculating small lymphocyte pool.
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  • 175
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    The @Anatomical Record 176 (1973), S. 65-83 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The nasal respiratory epithelium of the mouse has been studied at the ultrastructural level. The tissue was found to be a rather typical pseudostratified columnar ciliated epithelium, superficially different but basically similar to tracheal and bronchial epithelium in the same species, and clearly similar in most respects to that of other mammals. Four cell types were distinguished: ciliated columnar, secretory (goblet), intermediate, and basal.The ciliated cells, which exhibited typical surface cilia and microvilli, were characterized by a distinct stratification in the arrangement of subcellular components in their supranuclear cytoplasm. Beginning at the apical end and proceeding basally, the following strata were seen: an ectoplasmic region relatively free of organelles; an area rich in vesicular and tubular membrane profiles; a mitochondrial zone; a layer rich in ribosomes and polyribosomes; and a stratum of Golgi complexes.Secretory (goblet) cells were observed at various stages of secretion droplet accumulation. Cells in the earliest stage, characterized by a dense content of sER in the supranuclear cytoplasm, were similar to the “non-ciliated” cells of the mouse's lower respiratory tract. Some of the secretory cells contained dilated cisternae of rER which were engorged with a relatively electron-dense material. The possible significance of these inclusions is discussed.Unlike the other cell types, intermediate and basal cells displayed no features indicative of specialized function.
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  • 176
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    The @Anatomical Record 176 (1973), S. 121-123 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Total protein content of preimplantation mouse embryos was measured at 06.00 and 16.00 hours on day 5 of pregnancy (day 1, the day of vaginal plug formation). During this ten hour period, just prior to implantation, the amount of protein increased from 23 to 35 ng per blastocyst; a net increase of 52%. In contrast, protein content was unchanged in delayed implanting embryos recovered from ovariectomized animals during a comparable period on days 5 or 10 (day 5, 24 ng at 06.00 hours and 24 ng at 16.00 hours; day 10, 29 ng at 06.00 hours and 30 ng at 16.00 hours).These results demonstrate that the different uptake and incorporation of amino acids between normal and delayed implanting embryos (Weitlauf and Greenwald, '65, '68; Weitlauf, '73) reflect a difference in the actual net synthesis of protein by the two types of blastocysts.
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  • 177
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A description is presented of the peripheral blood cell values and blood cell morphology of both the normal and the starved red paradise fish. An inhibitory influence of food deprivation upon erythropoiesis was demonstrated in this fish by the significant decrease in red blood cell and hematocrit values. A comparative study showed that the size and numbers of erythrocytes present in teleost blood reflect its habitat, activity, and degree of evolution.
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  • 178
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Histological and ultrastructural observations of adenovirus-infused jejunal loops revealed virus particles in small apical tubules and in underlying vacuoles and lysosome-like bodies. Tissue selected from loops maintained for five and ten minutes disclosed virions largely within the intestinal lumen and in sparse tubular profiles beneath the microvilli. Jejunal preparations of longer duration disclosed increasing numbers of virus particles in small and large lysosome-like bodies above the nucleus. In no instance were virions apparent free within the cytoplasm or nucleus and none was observed elsewhere in the mucosa. It is concluded, therefore, that the jejunal absorptive cell behaves like its ileal counterpart in absorbing and sequestering adenovirus particles in intracytoplasmic lysosomal organelles. It is further proposed that this behavior might serve a protective role during the vulnerable period of immunologic immaturity in the neonatal mammal.
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  • 179
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    The @Anatomical Record 175 (1973), S. 1-6 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Adult guinea pigs were carefully standardized for at least seven days prior to each experiment; this included an artificial light-dark cycle with light extending from 0600 to 1800. On three experimental days, eight animals were injected subcutaneously with 300 μg of histamine at six-hour intervals over a 24-hour period; each animal received four injections during one day. The size of the erythema produced each time was measured. In all three experiments a prominent group rhythm was demonstrated with maximum response occurring during the dark phase; minimum response always occurred during the latter part of the light phase. Such results indicate a strong synchronization among the animals of the group.Two additional, similar studies were performed on animals standardized in one case for 21 days and in the second for 35 days under continuous illumination. The group rhythms of histamine response under these conditions, when compared to the light-dark adapted group rhythm, were greatly modified in phasing and profile. The circadian rhythm in response to histamine persisted in each individual animal. The change in the phasing and profile of the group rhythm was due to a partial desynchronization among the individual animals subjected to continuous illumination.
    Additional Material: 1 Ill.
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  • 180
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Unilateral explants of rat adrenal medulla grown in the anterior chamber of the eye were studied with light and electron microscopy. The surviving chromaffin cells are in proximity to the abundant vessels at 21 days after explantation. However, the typical arrangement of anastomosed cellular cords, such as can be always seen in the normal medulla, is replaced here by clusters, cords and irregular groups of cells. Two types of chroma & cells can be described. The predominant cells are polygonal or elongated in shape and have polymorphous and elongated norepinephrine-positive granules. The other type, less numerous, has a pale cytoplasm with round chromafh cells. This type is norepinephrine negative. Several cytological characteristics of some of the chromaffin cells are also described. These morphological observations are in agreement with the biochemical findings previously published and confirm that a signscant decrease of epinephrine cells occurs in the explant.
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  • 181
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An intercellular junction known as the nexus has been identified in developing granulosa tissue of rat ovaries. Nexuses are common in Graafian follicles of mature cycling rats and in similar follicles of immature animals stimulated by exogenous gonadotrophins. The angle at which the plane of section intersects a nexus significantly governs its internal appearance. Within obliquely cut nexuses there is often a cross-striated pattern of uniform lines in specimens prepared by conventional fixation and staining procedures. These lines could be significant because they may represent points of continuity between communicating cells.Two forms of nexuses are observed. The abutment form is found at cell surfaces, is continuous with plasma membranes, and is frequently associated with cell processes. The other form of nexus is ring-shaped and appears free within the cytoplasm. These circular profiles probably represent transverse views through nexus-girdled cell processes as well as nexus-bound spheres which may have pinched off the processes. Since the profiles from the two sources are ordinarily indistinguishable, both are designated “annular nexuses” even though some may be cell inclusions. Lanthanum tracer can percolate into the central region of abutment nexuses but is absent from the large majority of annular nexuses, suggesting that many of them are isolated from the extracellular space. Reconstruction of serial sections reveals that some annuli are parts of cell inclusions. Sphere formation could be a means of removing nexuses from cell surfaces.
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  • 182
    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 principal cells and intraepithelial leucocytes in the initial segment of the rat caput epididymidis was examined with the electron microscope. Specializations of the principal cells associated with absorption include numerous endocytic invaginations of the cell surface, numerous coated vesicles and multivesicular bodies in the apical cytoplasm. It was demonstrated that particulate tracers are taken into the cells and sequestered in secondary lysosomes and multivesicular bodies. Morphological features consistent with secretory activity are also found in the principal cells and include numerous cisternae of rough endoplasmic reticulum with a flocculent grey content and an extremely well-developed Golgi apparatus. The speculation that the principal cells are actively secretory despite the absence of secretory granules formed in the Golgi and of a visible mechanism for release of the product at the cell surface is discussed.The “halo cells” in the epididymal epithelium were also examined and it is shown that many of these cells are not typical migratory lymphocytes. Chief among the differences are their granule-containing multivesicular bodies and more abundant endoplasmic reticulum. Nonetheless, it is conceivable that the halo cells are lymphocytes and that the conditions they encounter as they leave the circulation and enter the epididymal epithelium may stimulate morphological changes. The possible immunological significance of these observations is discussed.
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  • 183
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    The @Anatomical Record 176 (1973), S. 461-474 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Primary explants from Rana catesbeiana tadpole liver have been maintained in organ culture for six days using methods of cultivation which are described in detail. The organization and morphology of the cells in culture have been defined by light and electron microscopy. By adjustment of the experimental conditions of culture, after six days, the cells are morphologically identical to those freshly excised from tadpole liver. Soon after being put into culture, however, the chromatin of the nuclei becomes condensed, and only after about 30 hours in culture do the original euchromatic characteristics of the nucleus reappear. The effects of changes in the culture conditions on these morphological characteristics are presented.The system that has been developed is discussed with a view toward elucidating the basis of the cytological changes which occur during anuran metamorphosis.
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  • 184
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    The @Anatomical Record 176 (1973), S. 475-487 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A large gland patch is found in the submucosa of the lesser curvature of the koala stomach near the entrance of the esophagus. It measures approximately 3 cm in diameter and is comprised of numerous invaginations continuous with the surrounding mucosa. The glandular invaginations drain into the lumen of the stomach by 25 to 30 large orifices. The mucosa of the gland patch invaginations differs from the mucosal lining of the stomach chiefly in thickness. The elongate gastric glands that comprise the invaginations exhibit an increased number of parietal and chief cells. Ultrastructural examination of the gland patch illustrates that the parietal, chief, and mucous neck cells are similar in structure to those of other mammalian species.
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  • 185
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    The @Anatomical Record 177 (1973), S. 23-37 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Male rats were maintained on a controlled feeding schedule and groups of animals sacrificed at 2, 15, 21, 36, 48 and 72 hours of fasting. Chemical determinations of glycogen showed that livers of rats fasted two hours contained 8.7% glycogen; 15 hours, 6.2%; 21 hours, 0.7%; 36 hours, 0.7%; 48 hours, 0.8%; and 72 hours, 0.4%. After PA/S procedures, glycogen appeared in hepatocytes of rats fasted 2 and 15 hours as large masses intensely stained. At these time-periods, almost all cells contained significant quantities of glycogen but hepatocytes located toward portal tracts showed larger and more intensely stained masses of glycogen than found in cells near central veins. After longer periods of fasting, glycogen masses decreased in size, number, and staining intensity. The fine structure of hepatocytes from rats fasted 2 or 15 hours showed abundant α and β particles of glycogen in the form of large masses throughout the cytosome. These correlated in position and shape to the masses of glycogen seen in the light microscope. As glycogen depletion occurred (fasted 21 hours and longer) the number of glycogen particles decreased in hepatocytes. It is concluded from this study that a good correlation exists between chemical determinations of hepatic glycogen, cytochemistry of glycogen in hepatocytes, fine structure of liver cells, and the fasting state of the animal.
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  • 186
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morphogenesis of chemical synapses in the trigeminal mesencephalic nucleus of the hamster was examined in the electron microscope. The relatively small complement of synapses and the simple geometry of these neurons facilitates quantitative analyses of synaptic development. Emphasis focused on the chronology of synaptic maturation and the length of the synaptogenic period in this nucleus. Synaptic endings first appear on the soma at three or four days after birth. These early terminals form desmosome-like junctions without any synaptic vesicles. The surface density of terminals (synapses/100 μm of perimeter) increases rapidly from 5 to 15 days when it is approximately equivalent to the adult. However, calculations that also take into account the expansion in cell surface area suggest that the actual number of terminals continues to increase as the cells grow. This indicates that these neurons may retain their synaptic capacity and continue to add new synaptic sites for a longer period than proposed for other systems. Structural characteristics of these synapses in the adult suggest they may be inhibitory in nature and thus regulate the interaction of electronically coupled clusters of neurons.
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  • 187
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Adjuvant-induced penetration of horseradish peroxidase (HRP) into seminiferous epithelium was studied as a model of adjuvant-induced entry of other proteins, e.g., immunoglobulins. HRP intravenously injected 20 minutes prior to sacrifice (by peraortic perfusion with Karnovsky's fixative) into male guinea pigs that had received Freund's complete adjuvant (FCA) + saline or FCA + testicular homogenate (TH) intradermally seven days previously, entered the peritubular spaces of a moderate number of seminiferous tubules. In those tubules HRP became uniformly distributed in the cytoplasmic matrices (but very rarely in membrane-bound vesicles) of some of the Sertoli cells and presumptive type B spermatogonia. By contrast, HRP injected into normal animals, into animals that had received FCA + saline or FCA + TH 3 or 14 days previously or into animals that had received Freund's incomplete adjuvant + saline 3, 7, or 14 days previously gained entry into only occasional peritubular spaces but was never found in any cells of the seminiferous epithelium.These findings are discussed in conjunction with previous findings on immune aspermatogenesis. Hypotheses concerning the intratesticular mechanisms of production of both active and passive immune aspermatogenesis as activated by FCA and the mechanisms whereby FCA may enable or potentiate production of immune globulins are proposed and discussed.
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  • 188
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    The @Anatomical Record 176 (1973), S. 149-165 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Acini of human parotid gland consist of pyramidal secretory cells and of flattened, basally placed, myoepithelial cells.Since secretory cells show a cytological organization intermediate between that of exocrine pancreas and that of mucous glands, human parotid is considered to be a seromucous gland. Short intercellular canaliculi extend between apical portions of secretory cells; more basally intercellular spaces, constantly separated from the lumen, are seen. Variations observed in cytology of secretory cells are believed to be more likely related to the presence of stages of a maturative cycle rather than to the existence of different types of cells. Secretory granules often show a bipartite structure consisting of a main portion and of a dense body (or core) contained in it. On the basis of the appearance of the main portion, dark and pale granules are recognizable. Dark granules are quite dense and homogeneous while pale granules, which tend to coalesce, are formed by a clear flocculent material. Together with granules endowed with intermediate characters, dark and pale granules are often present even in the same cell. Discharge of secretion into the lumen seems to take place following the fusion of the membrane of the secretory granule with the plasmalemma. In fact, bulging secretory granules and subluminal clefts are frequently seen. The shape of nuclei and the pattern of their chromatin content vary apparently with the cell cycle. Inside the nuclei, a distinct fibrous lamina, nucleoli and nuclear bodies are present. In addition, some nuclei exhibit a laminated inclusion arranged concentrically.Myoepithelial cells have an elongated body and thin processes extending among secretory cells. They are characterized by a filamentous cytoplasm poor in organelles.
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  • 189
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Embryonic and adult rodent tissues were fixed and prepared for scanning electron microscopy by dehydration in ethanol followed by critical point drying with liquid carbon dioxide or Freon 13 (E. I. du Pont de Nemours, Inc.). After coating the dried specimens with evaporated metal, the tissues were studied by scanning microscopy. The same tissues were subsequently embedded in Epon-Araldite, thin sectioned and examined by transmission electron microscopy. The cytological details in these specimens were comparable to tissues embedded directly, without drying or metal-coating. With this technique it is possible to identify with greater certainty the structures responsible for surface contours revealed by the scanning electron microscope.
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  • 190
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    The @Anatomical Record 176 (1973), S. 397-403 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Female mice were superovulated and mated, and the two-cell embryos were collected and cultured in vitro. The embryos were exposed to x-irradiation (0-491 rads) during the two-cell stage, before the appearance of the next cleavage plate, placed in new unirradiated culture medium and observed during subsequent development. Morphological abnormalities which occurred as a result of irradiation included fragmentation, disintegration, granulation, incomplete cleavage, cleavage cessation, nuclear degeneration and pycnosis and cytoplasmic vacuolization. There was no damage to the zona pellucida.The types of abnormalities indicated an agreement with the results of previous in vivo studies. A distinct correlation existed between morphological abnormalities and embryo death. The greatest number of abnormalities resulted within five hours following irradiation, but increased through 20 hours post-exposure. At doses above 300 rads, the magnitude of damage was greater in the in vitro embryos than that shown in previous in vivo studies.
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  • 191
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    The @Anatomical Record 177 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 192
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A comparison was made of changes in the morphology of fat cells in the intact mammary gland, de-epithelialized mammary fat pad, and the parametrial fat pad of female C3H mice during lactation. Mammary fat pad not in contact with actively secretory epithelium shows partial loss of fat during lactation (systemic effect) while in the presence of such epithelium there is much greater loss of fat (systemic plus local effect). In the same animal the parametrial fat pad shows greater depletion during lactation than the de-epithelialized mammary fat pad. The extent of fat depletion is dependent on the number of nursing young and the duration of lactation. In the intact mammary gland and parametrial fat pad, marked change in fat cell structure is not seen in pregnancy except possibly at the very end; after weaning, replenishment of lactation-depleted fat cells is conspicuous by 48 hours. The basic ultrastructure of mammary fat cells and the kinds of changes they undergo during depletion do not differ from those described for other mammalian adipose tissues.
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  • 193
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 194
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Nerves and major accessory ganglia of the pelvic plexus are described from 12 rats perfused with methylene blue. Nerves to ventral and dorsal aspects of the urinary bladder, and three groups of nerves to the penis (clitoris) are reported in detail.Myelinated nerve fiber diameters ranged from 1-10 μ in the pelvic nerve and 1-6 μ in the hypogastric nerve. When the pelvic nerve was deafferentated, by spinal ganglionectomy 28 days previously, 80% of myelinated fibers degenerated, and the remaining fiber-size spectrum resembled that of the hypogastric nerve. Myelinated fibers ranged from 1-7 μ in nerves to bladder and 1-3 μ in the lateral nerve to the penis. Myelinated fibers were afferent in these nerves, since spinal ganglionectomy eliminated all of them. In the main nerve to the penis, myelinated fibers ranged from 1-8 μ in diameter. A few fibers remained after deafferentation by spinal ganglionectomy. Since these were preganglionic efferent fibers, they indicate that terminal ganglia were present in the penis. All myelinated fibers degenerated with transection of pelvic and hypogastric nerves. The mode diameter of myelinated fibers was 2 μ in all pelvic plexus nerves.
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  • 195
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    Journal of Morphology 139 (1973), S. 227-237 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Marked external and osteological differences exist between the related cyprinids Couesius plumbeus and Rhinichthys cataractae. C. plumbeus differs from R. cataractae in several external features, such as eye size and mouth shape, any one of which permits identification of individuals. C. plumbeus has postcleithral and nasal bones while R. cataractae does not. Many differences in bone shape also exist. Natural hybrids between the two species from Upper and Lower Kananaskis reservoirs, southwestern Alberta, are intermediate in the average of their external and osteological characters. Some characters in the hybrids, however, are so variable that they fall within the range of both parental species. An individual hybrid may resemble one parental species in one diagnostic character and the other parental species in another. The largest individuals known of the three forms from the Kananaskis system are hybrids.
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  • 196
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 139 (1973) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 197
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    Journal of Morphology 139 (1973), S. 239-249 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histologic examination of ovaries from a non-migratory population of scrub jays (Aphelocoma coerulescens) disclosed a marked annual cycle in the incidence of atresia. Atretic follicles became more common as the nesting season progressed and were most abundant immediately after the cessation of breeding. Atresia involved a dissociation of granulosa cells and movement of these cells into the follicle. Subsequently, granulosa cells showed steatogenesis and ultimately disappeared simultaneously with the invasion of the follicle by ex-thecal gland cells. The data suggest that the diverse histology of avian atretic follicles reflects different stages in the process of atresia rather than multiple origins. Ovarian stromal glands apparently arise both from ex-thecal gland cells of atretic follicles and stromal connective tissue. A possible secretory role of atretic follicles is considered.
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  • 198
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A dichotomy of hair-cell types has been found in the bullfrog sacculus, and considerable evidence supports the view that one type (“peripheral”) is transformed during macular growth to the other type (“central”). Between the periphery and the center of the macula, one finds a gradation of form from “peripheral” to “central” type. Occasionally in adults and more often in stage-26 tadpoles one finds the presumably younger peripheral type of hair cell occurring well beyond the limits of the macula proper. The apparent morphogenic sequence for saccular hair cells is (1) development of a kinocillum on an endolymphatic epithelial cell, (2) gradual transformation of microvilli into stereocilia, (3) growth of the stereocilia and development of kinociliary bulb, (4) achievement of final size and form.
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  • 199
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    Journal of Morphology 139 (1973), S. 329-350 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Formation of secondary palate in hamster was studied with electron microscopy. Prior to assuming horizontal position, the palatal shelves were covered by a two to three cell layer thick epithelium which was separated from the underlying mesenchyme by an intact basal lamina. Epithelial cells were attached to each other by desmosomes. Early hemidesmosomes could be identified as thickenings of the cytoplasmic membrane opposing the basal lamina. Epithelial cells, like other embryonic cells, contained only few organelles but were rich in polyribosomes. As the horizontal shelves approached each other towards the midline, lysosomes and tonofilaments appeared in the superficial and basal cells of the epithelia. Superficial cells showed degeneration and eventual lysis. Fusion of the opposing epithelia occurred between the deeper cells by means of newly formed desmosomes. The epithelial seam resulting from fusion of the epithelia was limited on each side by a continuous basal lamina. Its subsequent thining and eventual fragmentation resulted from the loss of cells by autophagy. There was no evidence of mesenchymal invasion of the epithelial seam. Mesenchymal macrophages appeared in the later stage of palatogenesis and were responsible for phagocytosis of cellular debris.Formation of the soft palate was basically similar to that of the secondary hard palate and occurred by fusion of the opposing shelves. Similarly, anterior closure of the palate occurred by fusion of the lower end of the nasal septum to the primary and secondary palates. Hyperplasia of the opposing epithelia, prior to their fusion, was often seen.It is suggested that formation of the palate occurs in predictable and coordinated fashion and that timely appearance of lysosomes causing lysis of intervening epithelia is of great significance in normal palatogenesis.
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  • 200
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gross anatomical, histological and histochemical studies of heart development in Mexican salamanders, Ambystoma mexicanum, are reported. Gross observation suggests that heart development in this urodele species is similar to other amphibians. Histological studies in early embryos show the ventromedially migrating sheets of precardiac mesoderm to be composed of two layers of cells. The right and left dorsal layers fuse and give rise to the myocardium, while the ventral layers form the pericardium. The endocardium arises from cells released by the leading edges of the migrating mesoderm mantles. In early myocardial cells, most of the proteins and carbohydrates are contained in yolk platelets; subsequently, these substances become distributed throughout the cytoplasmic matrixes. In early heart cells free lipid droplets are abundant but decline in size and number as development progresses. Concomitantly, there is an increase in bound lipids. Reticular fibers are detected in the endocardial-myocardial spaces simultaneously with trabeculae formation. Collagen appears somewhat later in development.
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