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  • 1
    Electronic Resource
    Electronic Resource
    Mechanical factors in the evolution of the mammalian secondary palate: A theoretical analysis (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 199-213 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secondary palate of mammals is a bony shelf that closes the ventral aspect of the rostrum. The rostrum, therefore, approximates to a tapered semicylindrical tube that is theoretically a mechanically efficient structure for resisting the forces of biting, including the more prolonged bouts of mastication typical of mammals. Certain mammal-like reptiles illustrate stages in the development of the palate in which the shelves projecting medially from each premaxilla and maxilla do not meet in the midline. We evaluate several geometric properties of sections through the rostrum of the American opossum (Didelphis virginiana). For loading at the incisors and canines, these properties indicate the structural strength and stiffness in both bending and torsion of the rostrum and of single maxillae. We then repeat the analysis but progressively omit segments of the palatal shelf, a procedure which simulates, in reverse, the evolutionary development of the structure. The results demonstrate that the secondary palate contributes significantly to the torsional strength and stiffness of the rostrum of Didelphis and to the strength of each maxilla in lateromedial bending. The major evolutionary implications of the results are that the rapid increase in rostral strength with small increments of the palatal shelves may have been a significant factor in the development of the complete structure. The results indicate that there was a marked jump in torsional strength and stiffness when the shelves met in the midline, which is likely to have been important in the subsequent development of the diverse masticatory mechanisms of cynodonts and mammals. On the basis of this analysis the mammalian secondary palate may be interpreted as one of a number of methods, seen in the mammal-like reptiles, for strengthening the rostrum.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051890210
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  • 2
    Electronic Resource
    Electronic Resource
    Nuclear matrix as an anchor for protein kinase CK2 nuclear signalling (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 62 (1996), S. 165-171 
    Details
    ISSN: 0730-2312
    Keywords: nuclear matrix ; phosphorylation ; protein kinase CK2 ; chromatin ; nuclear translocation ; prostate ; cell growth ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Nuclear matrix (NM) is not only the structural basis for nuclear shape but also is intimately involved in nuclear functional activities. Among the modulatory factors that may affect these diverse activities are the signals that may influence the state or composition of the NM proteins. One such mechanism for altering the functional activity of at least some NM proteins may be the extent of their phosphorylation. Protein kinase CK2 appears to associate with NM and to phosphorylate a number of NM-associated proteins. Chromatin- and NM-associated CK2 is rapidly modulated by mitogenic signals. We propose that NM serves as a physiological anchor for nuclear signalling of protein kinase CK2 which may influence functions of NM such as transcription of active genes and growth. © 1996 Wiley-Liss, Inc. This article is a U.S. Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Association of protein kinase CK2 with nuclear matrix: Influence of method of preparation of nuclear matrix (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 64 (1997), S. 499-504 
    Details
    ISSN: 0730-2312
    Keywords: protein kinase CK2 ; nuclear matrix ; cytoskeleton ; chromatin ; intermediate filaments ; core filaments ; carcinoma ; prostate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Nuclear matrix (NM) plays roles of fundamental structural and functional significance as the site of replication, transcription, and RNA processing and transport, acting as an anchor or attachment site for a variety of enzymes and other proteins involved in these activities. We have previously documented that protein kinase CK2 translocates from the cytosol to the nucleus, where it associates preferentially with chromatin and NM, in response to certain growth stimuli. Considering that characteristics of the isolated NM can depend on the procedure employed for its isolation, we compared three standard methods for NM preparation to confirm the association of intrinsic CK2 with this structure. Our data suggest that the method used for isolating the NM can quantitatively influence the measurable NM-associated CK2. However, all three methods employed yielded qualitatively similar results with respect to the stimulus-mediated modulation of NM-associated CK2, thus further supporting the notion that NM is an important site for physiologically relevant functions of CK2. In addition, core filaments and cytoskeleton that were isolated by two of the preparative methods had a small but significant level of associated CK2 activity. J. Cell. Biochem. 64:499-504. © 1997 Wiley-Liss, Inc. This article is a U.S. Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Organization of tracheal epithelium in the cartilaginous portion of adult rabbit and its persistence in organ culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 238 (1994), S. 463-472 
    Details
    ISSN: 0003-276X
    Keywords: Trachea ; Organ culture ; Epithelial folding ; Rabbit ; Epithelial cell shape ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The rabbit trachea provides a model system to test the physiological responses of the airways to various agents. Since three-dimensional organization may affect responses of an organ, an organ culture model was established in serum free medium.Methods: Tracheas were fixed in situ, at steps in the preparation of organ cultures, and after one day to three weeks in organ culture. Samples were examined by light microscopy and scanning and transmission electron microscopy for surface morphology, distribution of cell types, and characteristics of the epithelial cell layer.Results: The normal tracheal mucosa was discovered to consist of extensive circumferential folds in the cartilaginous portion, which were enhanced upon isolation of the trachea from the animal. The folds consisted principally of differences in epithelial cell height rather than folding of the lamina propria. Enhancement of folding upon removal of the trachea coincided with increased secretion by Clara and possibly mucous cells. In organ culture, epithelial cell height initially increased, producing tall folds and cell types were retained in normal proportions. After prolonged culture, cilia were lost but glandular secretion continued.Conclusions: Changes in the arrangement of basal cells and secretory activity in isolated trachea and in culture may give insight into the functional significance of the epithelial folds. © 1994 Wiley-Liss, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092380405
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  • 5
    Electronic Resource
    Electronic Resource
    The ultrastructure of the cornea-lens epidermis in the lateral eye of Limulus polyphemusDr. R. Whitehead was supported by USPHS grants GM 572 and NB 5494. K. Hopper was supported by USPHS grant B-2567. This work is part of a research program supported by USPHS grant NB 05657. (1969)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 129 (1969), S. 31-57 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of the “Corneagen,” i.e., the epidermis lying beneath the cornea-lens of the lateral eyes of the adult intermolt Limulus polyphemus was studied with light and electron microscopy.This layer is composed of heavily columnar cells containing a striking number of cytoplasmic microtubules. Many of the microtubules are grouped into compact bundles or fascicles, generally each cell having at least one microtubule bundle. The cornealens end of each cell has numerous microvilli, each with a core of delicate filaments. The crypts between microvilli end in extracellular expansions and plaques of electron dense amorphous material are associated with these terminal expansions. Cytoplasmic microtubules appear to insert into these dense areas.The basal ends of the cells are thrown into many pseudopodial processes which extend into the surrounding extracellular space. The cytoplasm of the pseudopodia is composed largely of microtubules and their associated low density halos.Junctional complexes consisting of zonulae adhaerens and septate desmosomes are present between adjacent cells. Mitochondria, ER, cytoplasmic vesicles, Golgi stacks and other ultrastructural details of the epidermal cells are described. The ultrastructure of a column of pigment free processes lying between the apex of the lens cone and the underlying photoreceptive portion of the ommatidium is also described. Ducts or vessels of uncertain origin are present in the inter-ommatidial spaces.Possible roles played by the microtubules, the significance of their disposition and of their association with the dense subsurface plaques are discussed in terms of intracellular support, epidermis-lens attachment and extracellular pattern determination. In addition, the likelihood of the dense plaques being the site of microtubule assembly is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051290104
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  • 6
    Electronic Resource
    Electronic Resource
    Expression of Cdx-2 in the mouse embryo and placenta: Possible role in patterning of the extra-embryonic membranes (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 204 (1995), S. 219-227 
    Details
    ISSN: 1058-8388
    Keywords: Cdx-2 ; Homeobox ; Placental patterning ; Gut ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Three mouse homologues of the Drosophila homeotic gene Caudal (Cad) have been described. They are currently designated Cdx-1, Cdx-2, and Cdx-4. Cdx-1 and 2 are both strongly expressed in the adult mid- and hindgut, while Cdx-1 and 4 have been shown to be activated in the embryonic primitive streak. Using a polyclonal antibody against a fusion protein containing the amino terminal 109 amino acids of murine Cdx-2, we here describe the topographical location of the gene product from early cleavage to 12.5 days of embryonic development. Cdx-2 expression begins at 3.5 days and is confined to the trophectoderm, being absent from the inner cell mass. Subsequently, staining is located in the extra-embryonic ectoderm adjacent to the epiblast, but sparing the more superficially placed polar, as well as the mural trophoblastic cells. Continuing expression in the fetal membranes involves the chorion, the allantoic bud, and, at even later stages, the spongiotrophoblast. From 8.5 days, Cdx-2 begins to be expressed in embryonic tissues, principally (unlike Cdx-1) in the posterior part of the gut from its earliest formation, as well as in the tail bud and in the caudal part of the neural tube. Cdx-2 is, therefore, transcribed well before any other membrane of the Cad homologue group and of the related Hox-C group; its expression in the extra-embryonic membranes and in the hindgut reflects the phylogenetic relationship between the cloaca and the chorio-allantois and suggests the possibility that homeobox genes may be involved in placental development and/or patterning. © 1995 wiley-Liss, Inc.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1002040302
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  • 7
    Electronic Resource
    Electronic Resource
    A morphometric study quantifying the mucus content of proliferating colonic epithelial cells (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 155 (1979), S. 103-109 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We report a quantification of the maximum mucus accumulation in proliferating rat colonic epithelial cells. The proliferative potential was determined by radioautographic study of one-hour pulse exposures to tritiated thymidine, mucous content was determined by Periodic-acid Schiff (PAS) staining. We examined 55 labeled mucous cells in 0.5- to 1-μm serial sections. The maximum thecal and nuclear profiles of these cells were photographed and their surface areas were determined utilizing a coordinate sensor. The data were expressed as a theca-to-nucleus (T/N) ratio. The maximum (T/N) ratio for a labeled mucous cell was 3.0. We performed a similar analysis on 22 unlabeled mucous cells from upper crypt regions and surface epithelium to derive the range of (T/N) ratios for terminally differentiated mature mucous cells. The range of (T/N) ratios from these cells was from 4.8 to 16.4. Our study shows that proliferative potential of mucous cells is determined by the interrelationship between mucus accumulation and nuclear size.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001550107
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  • 8
    Electronic Resource
    Electronic Resource
    Initiation and pattern of angiogenesis in wound healing in the rat (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 192 (1991), S. 257-262 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The object of this study was to examine the initiation and pattern of capillary growth associated with wound healing. Collagen sponges were implanted subcutaneously in the hind limbs of adult male rats to stimulate the formation of granulation tissue. Blood vessels of the hind limbs of euthanized rats were perfused with Mercox (an acrylic monomer) via the abdominal aorta at selected periods of time following sponge implantation. When the perfusate was completely cured, the sponge and parajacent tissues were excised and subsequently macerated by alternating immersion in 40% KOH and distilled water. Cast replicas of the vascular lumina were coated with gold and imaged by scanning electron microscopy. At 6 hr, punctate depressions at the periphery of the replicas of vein and venule lumina were noted. The depressions represented sites of leukocyte margination. By 24 hr, the depressions increased numerically, indicating a great increase in the sites of leukocyte margination. The number of these depressions decreased by 48 hr. Concomitantly, the depressions representing endothelial cell nuclei became more pronounced, indicating nuclear hypertrophy of these cells. In addition, capillary bud formation was initiated. At 72 hr, capillary buds were quite apparent and arose solely from venules. Between 7 and 14 days, replicas of capillary lumina were longer and formed an elaborate network, presumably by end-to-end, side-to-side, and end-to-side anastomoses. The network was formed circumferential to the sponge and then capillary sprouts entered the sponge's interstitial spaces.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001920305
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