bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of hamster tracheal epithelium: III. Illustration of statistical methods for proportional data in biology
Authors: Coleman Bill , McDowell Elizabeth M. 
Published: February 2005

AbstractThe data in the two companion papers (McDowell et al., 1985a,b) are of a commonly occurring type in which the dependent variable takes on one of a small number of distinct values; we wish to compare the relative proportions in which these values occur. Student's t test is inapplicable. We explain here in detail the linear logistic model that is appropriate, using our data as an example.Several reasonable models must first be fit. We did this by the maximum likelihood method, using a computer. We then used a x2 test to decide statistically between models. This process amounts to deciding directly which of the independent variables are important in determining the outcome, and thus it is the center of physiologic interest.The outcome depends on the initial choice of parameterization of the model. Generalizations are required in more complicated, but still commonly occurring, types of data.
Localization and development of immunoreactive triiodothyronine in thyroid glands of dogs and chickens
Authors: Kameda Yoko , Udatsu Kyoko , Horino Masaharu , Tagawa Takasuke 
Published: February 2005

AbstractThe localization of immunoreactive T3 was investigated in dog and chick thyroid glands either fixed in Bouin's solution or freeze‐dried and fixed with paraformaldehyde vapor, and compared with localization of 19S‐thyroglobulin. Freeze‐drying followed by paraformaldehyde vapor was better for the demonstration of T3 than Bouin's solution; it gave a much stronger immunoreactivity for T3. This fixative was also excellent for the demonstration of thyroglobulin. The immunoreactive T3 was detected only in the colloid and was never observed in the follicular cells, although immunoreactive thyroglobulin was present not only in the colloid but also in the follicular cells. Subsequently, in dog fetuses and chick embryos the appearance and development of immunoreactive T3 were studied. At 40 days of gestation in dog fetuses and at 9 days of egg incubation in chick embryos, immunoreactive T3 was found in the colloid of primordial follicles coinciding with the formation of the colloid. The ability of embryonic thyroid glands to synthesize T3 seems to be linked to the organization of follicles. With progressing development, the follicles stored more colloid and immunoreactive T3 within the follicular lumina. Concentrations of immunoreactive T3 in thyroids from chickens at various stages of development were also studied by radioimmunoassay. The T3 concentration was first detected at 9 days of incubation and gradually increased with embryo age; it was related to the amounts of colloid stored in the follicles.
The sensory innervation of the rat rhinarium
Authors: Silverman Richard T. , Munger Bryce L. , Halata Zdenek 
Published: February 2005

AbstractThe present study documents the characteristics of innervation of the rhinarium or hairless rat snout skin by light and electron microscopy. The outer glabrous surface is covered with a stratified squamous epithelium that forms both rete pegs and rete ridges, the latter on the inferior border near the philtrum. The glabrous skin contains numerous presumptive epidermal and dermal free nerve endings (FNE's), Merkel terminals at the base of the rete ridges and pegs, and simple, nonencapsulated corpuscles. A second region of dense innervation, found on an elevation of the inner wall of the vestibule, contains similar components of innervation, with the exception that no Merkel terminals were identified. Since no Merkel terminals were present in this area of the vestibule, intraepidermal as well as dermal FNE's could be identified with certainty. This skin is covered by a thin squamous epithelium overlying dense connective tissue. The simple corpuscles are similar to those in the rhinarium, as well as resembling those described in other species. FNE's were frequently observed intimately associated with simple corpuscles. Several examples of large FNE's with two to three layers of cytoplasmic lamellae were found, suggestive of transitional forms between FNE's and simple corpuscles.Thus, the pattern of sensory innervation in the glabrous rat snout skin is similar to that found in other furred species described to date, but in addition, the sensory innervation of ridged skin in the rat also resembles that of epidermis organized into rete pegs. This dense sensory innervation may be correlated with whisking behavior of the predominately nocturnal rat.
The ontogeny of nexuses (gap junctions) in the ovary of the fetal mouse
Authors: Mitchell Philip A. , Burghardt Robert C. 
Published: February 2005

AbstractNexuses (gap junctions), the morphological correlates of direct cell‐to‐cell communication, were consistently detected between granulosa cells of primordial follicles in the ovaries of adult cycling, juvenile, or neonatal mice. To examine the ontogeny of these intercellular channels, the cellular interactions occurring during the fetal stages of folliculogenesis, which culminate in the formation of primordial follicles, were analyzed in ovaries from fetal days 13, 15, 17, and 19. On fetal day 13, the ovary is characterized by clusters of germinal cells and invading rete ovarii cells. The rete cells progressively penetrate the ovary and wall off clusters of oocytes by fetal day 17, at which time rete cells can be recognized as presumptive granulosa cells. Gap junctional contacts can be recognized between rete cells on day 13 and these contacts persist as the cells become recognizable as presumptive granulosa cells throughout ovarian histogenesis. Quantification of junctional contacts from days 15–19 indicated that the number of gap junctions increases with fetal age. In addition heterocellular gap junctional contacts were detected between oocytes and presumptive granulosa cells as early as fetal day 17, indicating that the potential for direct intercellular communication between granulosa cells and oocytes is established from the earliest contact.
Differentiation kinetics of osteoclasts in the periosteum of embryonic bones in vivo and in vitro
Authors: Scheven Ben A. A. , Kawilarang‐De Haas Elisabeth W. M. , Wassenaar Anne‐Marie , Nijweide Peter J. 
Published: February 2005

AbstractOsteoclast progenitors are seeded via the blood stream in the mesenchyme surrounding embryonic long bone models long before the appearance of multinucleated osteoclasts. The proliferation and differentiation of these progenitors in embryonic mouse metatarsal bones was studied with acid phosphatase (AcP) histochemistry and 3H‐thymidine autoradiography.In vivo, tartrate‐resistant, acid phosphatase‐positive, mononuclear cells appear in the periosteum (AcPP‐P cells) at the age of 17 days (after conception). On day 18, AcP‐positive, multinucleated osteoclasts invade the bone rudiment and start resorbing the calcified cartilage matrix, resulting in the formation of the marrow cavity.The kinetics of osteoclast formation in vitro was studied in metatarsal bones of embryonic mice of different ages cultured in the continuous presence of 3H‐thymi‐dine. In young bones (15 days), mainly proliferating, 3H‐thymidine‐incorporating progenitors gave rise to AcPP‐P cell and osteoclast formation. In older bones (16 and 17 days) osteoclasts were progressively more derived from postmitotic, unlabeled precursors. Irradiation of the metatarsal bones with a radiation dose of 5.0 Gy prior to culture resulted in a selective elimination of the proliferating progenitors, whereas the contribution of postmitotic precursors in AcPP‐P cell and osteoclast formation remained unchanged. The results demonstrate that in the periosteum of embryonic metatarsal bones a shift occurs from a population composed of proliferating osteoclast progenitors (15 days) to a population composed of postmitotic precursors (17 days) before multinucleated osteoclasts are formed (18 days). Obviously, postmitotic AcP‐negative precursors, already present in 16‐day‐old bones, differentiate into precursors characterized by tartrate‐resistant AcP activity, the preosteoclasts (17 days), which in their turn fuse into osteoclasts.
Development of the atrioventricular valve region in the human embryo
Authors: Magovern Jamie Hall , Moore G. William , Hutchins Grover M. 
Published: February 2005

AbstractSevere cardiac malformations may involve the atrioventricular valve region, but the sequence of embryonic development of this important area has been little studied. In particular, the basis of atrioventricular muscular discontinuity, except at the conduction system, has remained unexplained. To examine this question, serial histologic sections of human embryos from the Carnegie Embryo‐logical Collection and from the Hopkins Pathology Collection were studied and six embryos were reconstructed. The atrioventricular sulcus can be identified in Carnegie stage 10 as an indentation or crease on the right side separating the heart tube from the umbilical vein. By stage 12 the sulcus has deepened and rotated anteriorly as the atria appear and the heart tube elongates rapidly within the confining pericardial space. Selective accumulation of cardiac jelly on the endocardial aspect of the constriction of the heart tube produced by the atrioventricular sulcus is pronounced by stage 14. By stage 16 the separation of the atrioventricular orifice into right and left components is well advanced, and by stage 18 the septation of the atria and ventricles is largely complete. The muscular connection between the atria and the ventricles becomes interrupted around most of the artioventricular sulcus, except for the His bundle, during the latter part of the embryonic period. The topography of the original sulcus assumes a catenoidal or saddle‐shaped configuration, i.e., convex in one plane and concave in the perpendicular plane. The tension and pressure relationships in such a structure would favor cardiac jelly accumulation and the eventual disintegration of lines of myocyte connections passing across the groove. The preservation of the His bundle connection is explained by the failure of the sulcus to completely encircle the heart.
A scanning electron microscopy and histological study on the effects of the mutant eyeless (e/e) gene upon the hypothalamus in the Mexican axolotl Ambystoma mexicanum Shaw
Authors: Eagleson Gerald W. , Malacinski George M. 
Published: February 2005

AbstractA scanning electron microscopy, histological, and immunochemical investigation examined the effects of the mutant gene (e) upon hypothalamic development in the Mexican axolotl. The adult eyeless mutant is sterile. Previous studies indicated that this reproductive defect was due to the mutation's effect upon the hypothalamus.The present study demonstrated the pleiotropic effects of the eyeless gene upon development of the hypothalamus. Scanning electron microscopy studies looked at the early ontogeny of the hypothalamohypophyseal system. The major morphological difference observed in the hypothalamus of normals compared to eyeless mutants was the reduced nature or complete lack of a preoptic recess in eyeless mutants. Early embryonic tissue movements also differed when normal siblings were compared to eyeless mutant axolotls. Histological examination looking for paraldehyde‐fuchsin‐positive secretory neurons revealed a paired nucleus preopticus in both normals and eyeless mutants, but this region lacked the emanating paraldehyde‐fuchsin‐positive fiber tracts in eyeless mutants. The neurohypophysis of the eyeless mutants was atrophied and contained far less paraldehyde‐fuchsin‐positive material when compared to normal axolotls.Immunochemical studies were done to look at the distribution of immunoreactive luteinizing‐hormone‐releasing hormone (ir‐LHRH) in brains of eyed and eyeless mutant axolotls of different stages. This study detected deficiencies in ir‐LHRH in the anterior hypothalamus of eyeless mutants.In general in the eyeless mutant axolotl, the observed anterior hypothalamic deficiencies are comparable to those observed in anurans which have had their optic vesicles removed. These observations suggest a possible utility of the eyeless mutant axolotl for studies concerned with endocrine development in the absence of hypothalamic modulation.
Calcium‐binding protein (28,000 Mr calbindin‐D28k) in kidneys of the bullfrog Rana catesbeiana during metamorphosis
Authors: Rhoten William B. , Gona Ophelia , Christakos Sylvia 
Published: February 2005

AbstractA protein of approximately 28,000 relative molecular mass (Mr) cross‐reacting with antiserum against the 28,000‐Mr rat renal calcium‐binding protein (calbindin‐D28k) has been localized in the kidney of a salientian amphibian, Rana catesbeiana. Cells reactive for calbindin‐D28k were found in the distal tubule at all stages of metamorphosis by the unlabeled antibody peroxidase‐antiperoxidase technique. Adult kidneys appeared to have more calbindin‐D28k‐positive cells. The renal corpuscle, neck, and proximal tubule were negative. An immunoreactive 28,000‐Mr band that comigrated with the band of calbindin‐D28k was visualized by the immunoblot technique. The finding of the 28,000‐Mr calbindin‐D in the anamniotic kidney demonstrates that this calcium‐binding protein (CaBP) is phylogenetically older than our previous studies of higher vertebrates had revealed (Rhoten et al., 1985). Although the function of calbindin‐D28k in the distal nephron is unknown, this CaBP can now be presumed to have functional significance in the mesonephric as well as the metanephric kidney.
Morphology of ventral epidermis of Rana catesbeiana during metamorphosis
Authors: Robinson Douglas H. , Heintzelman Matthew B. 
Published: February 2005

AbstractA detailed morphological examination of the bullfrog tadpole ventral epidermis and changes in structure that occur during metamorphosis has not been done. Knowledge of this is crucial to interpretation of physiological studies such as those dealing with development of transepithelial Na+ transport. Examination of tadpole epidermis with light microscopy reveals the presence of three different cell types: apical, basal, and skein. This epidermal morphology is constant until Taylor and Kollros (Anat. Rec. 94:7–23, 1946) stage 19 when degeneration of apical cells is noted. Stages 20 and 21 are characterized by rapid proliferation of basal cells and development of a true stratum germinativum together with the disappearance of other tadpole cell types. By stage 22, epidermal morphology is similar to that of the adult frog. Studies with the electron microscope reveal that as the proliferation proceeds during metamorphosis, the skein cells, at stage 20, differentiate to form the apical border of the skin. The development of the adult frog cell phenotype appears to mimic the cellular differentiation that occurs in the adult epidermis with the cells first developing into progranular cells in the intermediate stratum of the skin and then progressing to granular cells in the outermost living cell layer. The granular cells then undergo cornification to form the stratum corneum. Mitochondria rich cells are not seen in the developing epidermis until stage 21. These observations, when considered with previous results from Na+ transport studies (Hillyard et al.: Biochim. Biophys. Acta 692:455–461, 1982), suggest that both the physiological differentiation and morphological differentiation are simultaneous events.
Maturation of human fetal esophagus maintained in organ culture
Authors: Ménard Daniel , Arsenault Pierre 
Published: February 2005

AbstractThe purpose of this work was to study the human fetal esophagus maintained in organ culture. Esophageal explants from 8 fetuses aged from 12 to 16 weeks of gestation were cultured up to 21 days at 37°C in Leibovitz L‐15 serum‐free medium. Between 12 and 16 weeks of gestation, the esophagus has a stratified columnar ciliated epithelium, and glycogen aggregates are present in all cell layers. This morphology remains the same up to 5 days in culture. After 7 to 9 days, a vacuolization in the upper half layer occurs, leading to a lifting off of the ciliated layer and a flattening of the subjacent cells. After 15 days of culture, the esophageal epithelium is stratified squamous and the cells are exfoliated at the surface of the explants. Glycogen aggregates are still present in all layers. Islets of ciliated cells resting on the basal cell layers develop within the squamous epithelium. With the extension of the culture period up to 21 days, the general morphology of the epithelium does not change. The ultrastructural features of the newly formed squamous epithelium, with its basal lamina, are similar to that reported for human adult esophageal epithelium. During the course of the culture, the DNA synthesis continues as determined by autoradiography. It is concluded that it is possible to maintain viable human fetal esophagus in organ culture and that an accelerated maturation takes place leading to the formation of the adult esophageal epithelium.
Arterial supply to the pig intestine: An unusual pattern in the mesentery
Authors: Spalding Hugh , Heath Trevor 
Published: February 2005

AbstractThe arrangement of arteries in the mesentery in pigs was studied with latex casts and light microscopy. Arterial arcades, which are characteristic of the mesentery in man and other species, are absent. Instead, a narrow band of numerous, anastomosing arteries gives rise to up to about 500 bundles of arteries and accompanying veins, which radiate out in the mesentery. Each bundle contains up to 30 arteries, but these recombine as they approach the jejunum, and form 1–4 arteriae rectae.The significance of the very large number of small arteries in the mesentery is not known, but they may play a role in the control of blood pressure in the intestinal wall, or as sites of countercurrent exchange.
The role of function in the development of human craniofacial form—A perspective
Authors: Kean M. R. , Houghton P. 
Published: February 2005

AbstractAs an anatomical region the head combines great diversity of function with close integration of structure. Consequently no structural component has autonomy of form. There is a sequence of maturation of functions and their related structural components, and in this sequence the nervous system and its supportive structures mature first. The nasal airway matures next in response to increasing body mass, and the masticatory system constitutes the last major functional system to reach maturity. The later the maturation of the function, the greater is the requirement for its related morphology to adapt to preceding skeletal templates. These matters of developmental sequence, and extrinsic as well as intrinsic craniofacial functions, are paramount considerations in interpreting the form of any component of head anatomy.
Immunolocalization of extracellular matrix proteins and collagen synthesis in first‐trimester human decidua
Authors: Kisalus Lydia L. , Herr John C. , Little Charles D. 
Published: February 2005

AbstractThe extracellular matrix (ECM) of first‐trimester human decidua was examined with indirect immunofluorescence using affinity‐purified antibodies to human collagen types I, III, IV, V, laminin, and fibronectin. In addition, the validity of the classification “mesenchymal‐epithelioid” for differentiated decidual cells was addressed using antibodies to the intermediate filament proteins, vimentin, a mesenchymal marker, and keratin, an epithelial marker. Biosynthesis of extracellular matrix components was examined by radiolabeling of decidual explants in culture with 3H‐proline, followed by immunoprecipitations of synthesized proteins with collagen type‐specific antibodies. Immunofluorescence showed decidual cells are embedded in an extensive network of collagen types I and III, and intracytoplasmic staining suggested synthesis of these collagens by the decidual cells. Collagen type IV and laminin localized in the external lamina which surrounds the differentiated decidual cell, and some fluorescence was evident in the peripheral cytoplasm. Immunoreactive collagen type V was observed in close association with the external lamina and in the peridecidual matrix. Fibronectin localized throughout the decidual ECM and in fibrillar and punctuate patterns in the decidual cell cytoplasm. Differentiated decidual cells retained a “mesenchymal” intermediate filament cytoskeleton containing an abundance of vimentin filaments, but very few, if any, keratin filaments. Collagen types I, III, V, and to a lesser extent, IV, were immunoprecipitated from the medium of decidual explants after 24 hours of culture, demonstrating in vitro synthesis and secretion of these collagens by first trimester human decidua.
Effect of optic nerve denervation on lens regeneration in adult newts, Triturus viridescens
Authors: Chan Frank , Orsbon Susan 
Published: February 2005

AbstractThis experiment was designed to study the effect of optic nerve denervation on lens regeneration. Adult newts, Triturus viridescens, were divided into 4 groups: A) lentectomized newts, which served as controls, B) lentectomized newts with the optic nerve exposed and lightly palpated, C) newts with lens removed and the optic nerve cut simultaneously, and D) newts with lens removed frist and optic nerve cut 7 days and 14 days later. Control animals required about 21 days to produce a new lens, and animals in group B demonstrated the same regeneration rate. In groups C and D, the regeneration rate was greatly retarded during the first 14 days. However, most of these animals regenerated a perfect new lens by 21 days postlentectomy.
Neurulation in the mouse I. The ontogenesis of neural segments and the determination of topographical regions in a central nervous system
Authors: Sakai Yoshio 
Published: February 2005

AbstractOntogenesis of neural segments and positional relationships between the segments and other organs during neurulation were studied in 1,423 ICR mouse embryos by binocular dissecting, light, and scanning electron microscopy.Late in the presomite stage, two transverse sulci, preotic and otic, were seen on the prospective luminal surface of the neural folds. By somite stage 19, the former subdivided into five neuromeres, and by somite stage 21, the latter subdivided into four neuromeres. From the rostral, preotic sulcus, moreover, five other neuromeres were formed by somite stage 20, and between the otic sulcus and the first somite, two neuromeres were formed by somite stage 28. In the caudal part, from the level of the first somite, a total of 39 neuromeres were formed one after another by somite stage 39, and their positions almost correlated with each corresponding somite.Furthermore, the isthmus grew in the boundary between the fifth and sixth neuromere. The most protruding zone in the preotic sulcus formed the eighth neuromere and was located adjacent to the first branchial arch and the trigeminal ganglion. The most protruding zone in the otic sulcus also formed the 11th neuromere and was located adjacent to the second branchial arch. The 12th and 13th neuromeres were situated adjacent to the otic vesicle; the 23rd to 28th neuromeres, adjacent to the forelimb bud; and the 40th to 46th neuromeres, adjacent to the hindlimb bud.