bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytoarchitectural reorganization of rabbit colonic goblet cells during baseline secretion
Authors: Radwan Khaled A. , Oliver Mary G. , Specian Robert D. 
Published: February 2005

AbstractLight and electron microscopy were coupled with point counting methods to quantitate shape and volume changes of goblet cells during their migration and maturation from the base of the crypt to the colonic surface epithelium in the rabbit. After differentiation, goblet cells attain a broad pyramidal configuration in the basal third of the crypt. The cells elongate and dramatically decrease in volume as they move into the surface epithelium. The distributions and volume fractions of organelles were found to vary considerably, depending on the location of the goblet cell in the epithelium. Mucin granules are initially synthesized throughout the cytoplasm, but become increasingly concentrated as the cell matures. Organelles involved in synthesis such as the Golgi apparatus and rough endoplasmic reticulum (RER) similarly attain a more concentrated arrangement as the cell moves up in the crypt. The mean cell volume decreases from 1,228.8 μm3 for cells in the basal third of the crypt to 541.3 μm3 for goblet cells on the surface. Most organelles decrease in proportion to this decrease, although a disproportionately large decrease in the RER was measured. When actual subcellular volumes are calculated, a net decrease in several subcellular compartments is detected. This loss of granules and organelles is accomplished by the continual synthesis and secretion of mucin granules. Cytoplasm and organelles become entrapped in the upward movement of granules towards the cell apex, become irretrievably isolated, and are sloughed into the crypt lumen. This process accounts for the decrease in cell volume and contributes to the altered cytoarchitecture of the cell.
Spontaneous or experimentally induced formation of a special zone in the adrenal cortex of the adult brush‐tailed possum (trichosurus vulpecula)
Authors: Kerr J. B. , Weiss M. 
Published: February 2005

AbstractThe cytology and ultrastructure of the hypertrophied special zone, which is formed spontaneously in the adrenal cortex of adult female brush‐tailed possums (Trichosurus vulpecula), was compared to the adrenocortical tissue in adult males in which the special zone, normally absent, was induced following castration alone or by additional treatment with folliclestimulating hormone (FSH).The special zone in females was situated between the zona fasciculata and the zona reticularis, the latter being a rudimentary zone in this species. Special zone tissue extended as a broad band parallel to and on one side of the adrenal medulla. In the luteal phase of the reproductive cycle, the special zone cells showed ultrastructural features commonly associated with steroidogenic tissues, with many mitochondria and compact masses of smooth endoplasmic reticulum. Cytoplasmic lipid inclusions were rarely observed. In lactating females, however, the special zone cells exhibited cytological and ultrastructural features suggestive of a transformation in their morphology broadly divided into two types of cells: (1) cells at the periphery of the special zone (closest to the zona fasciculata) showed variable quantities of lipid inclusions, mitochondria with dispersed cristae, and segregation of the smooth endoplasmic reticulum into compact masses; (2) cells within the more central regions showed an increasing abundance of lipid inclusions which in many cells became the dominant feature of the cytoplasm. These special zone cells contained very little smooth endoplasmic reticulum and their mitochondria contained few cristae together with amorphous granular material within the matrix.In castrated males, special zone tissue developed between the zona fasciculata and the zona reticularis, appearing initially as focal islands of cells (8 months postcastration) and later (11 months postcastration) expanding into a single zone, probably via the proliferation and differentiation of adjacent cells of the zona fasciculata and longitudinal growth of the special zone. Similar focal aggregations of special zone cells were induced after 14 days of FSH treatment given to 2‐month castrated males. In all castrated and FSH‐treated castrated males, the ultrastructure of special zone cells was similar to that of special zone cells in luteal‐phase female possums.The findings suggest that the formation and cellular composition of the special zone is associated with changes in the pituitary‐gonadal axis and that FSH plays a primary role in the differentiation of this tissue.
Branchings and course of the larger ducts and accompanying structures within the rat submandibular salivary gland
Authors: Lorber Mortimer 
Published: February 2005

AbstractIn the rat submandibular gland, the larger ducts, vessels, and AUtonomic elements are surrounded by appreciable collagen to form an extensive, ramifying core for the bulk of the parenchyma. This entity is analogous to the armature within a clay sculpture becAUse it provides a framework supporting softer surroundings. Its largest portion, the trunk, begins dorsorostrally at the hilus. Along its cAUdal course, the trunk emits limbs that, in turn, branch. Rostrally, the trunk and major limbs have their greatest diameters and contain lymphatic vessels and AUtonomic ganglia that are fewer or absent in the smaller divisions. Four to six orders of branching commonly occur. This architectural device constitutes a physical gradient which peaks at the hilus and is minimal where its components undergo the transition to the lobular parenchyma. The presence of an appreciable amount of connective tissue, nerves, and larger vessels would make this entity firmer than the highly hydrated parenchyma. The major divisions of this grouping are contacted by septa that extend from the organ capsule and demarcate lobules into which smaller divisions penetrate. The parenchyma is consequently ensconced between several strong structures containing abundant connective tissue. The dense collagen encompassing individual components of the biological armature would stabilize duct epithelium and its intercellular channels as well as brace vessels' walls. As a result of this architectural arrangement, the patency of all acinar, duct, and vascular structures is likely to persist despite neck and jaw movements that would otherwise distort them and thus hinder the formation and flow of saliva during feeding. This mechanism may be widespread among organs.
Immunohistochemical studies of the extracellular matrix in the condylar cartilage of the human fetal mandible: Collagens and noncollagenous proteins
Authors: Ami Yechiel Ben , Von Der Mark Klaus , Franzen Ahnders , De Bernard Benedetto , Lunazzi Gian Carlo , Silbermann Michael 
Published: February 2005

AbstractThis study provides data concerning the cells and their extracellular matrix in prenatal human mandibular condylar cartilage. The latter cartilage represents a secondary type of cartilage since it develops late in the morphogenesis of the craniofacial skeleton. The cartilage of the mandibular condyle is actively involved in endochondral ossification, thus showing all the phases of cartilage growth, maturation, and mineralization that precedes de novo bone formation. The present study focused on the localization and distribution of the major macromolecules that are normally encountered in cartilage and bone, including colagens, proteoglycans, fibronectin, osteonectin, osteocalcin, alkaline phosphatase, and anchorin CII. It became clear that the mineralized zone of the cartilage already contained bone‐specific antigens; thus the above zone might serve as an essential propagative predecessor in the ossification process.
Immunohistochemical localization of atrial natriuretic peptide in the developing and adult mammalian kidney
Authors: McKenzie James C. , Scott Jane N. , Inagami Tadashi 
Published: February 2005

AbstractThe discovery, within the last decade, of atrial natriuretic peptide (ANP), a family of peptides with natriuretic/diuretic and vasorelaxant properties, has prompted much research into the mechanisms and sites of action of ANP within the kidney. In the present study, ANP was localized in the kidneys of several mammalian species by immunohistochemical techniques (1) to identify possible sites of synthesis; (2) to compare the localization of ANP to known physiological effects; (3) to determine species differences, if any, in ANP localization; and (4) to study the development of ANP immunoreactivity in the fetal and neonatal rat kidney. Using an antibody against rat ANP IV, ANP was localized exclusively on the proximal convoluted tubule (PCT) brush border and within intercalated cells of the outer medullary and cortical collecting tubules and ducts of adult mouse, rat, pig, monkey, and human kidneys. The development of ANP immunoreactivity paralleled the differentiation and maturation of collecting duct epithelium in rat fetal kidney. Atrial natriuretic peptide found within intercalated cells of the cortical and outer medullary collecting ducts may be the result of endogenous synthesis and, following secretion, may be available to receptors in the inner medullary collecting ducts.
Development of anencephaly and its variants
Authors: Müller Fabiola , O'Rahilly Ronan 
Published: February 2005

AbstractExtreme variants of anecephaly in two human embryos of the same stage, namely 22 (54 days), shed new light on problems such as craniocerebral interrelationships and the timing of developmental events. Embryo X had a chondrocranium that possessed features typical of a holoacranial anencephalic skull and an extremely well‐preserved brain, in which some of the neural tracts were comparable to those in a normal control. On the other hand, embryo Y of the same stage had a completely degenerated brain, although the chondrocranium was more nearly normal and represented the precursor of a meroacranial skull. A comparison of the two cases seems to indicate a certain independence between skull and brain. Moreover, it appears possible that the disturbances are related primarily to the skeletal, and only secondarily to the nervous, component. Comparisions with experimental data allow the conclusion that the maldevelopment involves mostly paraxial mesenchyme and little or no disturbance of neural crest. The timing of the mesenchymal defect is probably as early as stages 8 and 9 (18–20 days). This is also the time at which mesenchymal defects can result in failure of the neural tube to close.
Renal morphology of the hook‐lipped african rhinoceros, Diceros bicornis, linnaeus
Authors: Maluf N. S. R. 
Published: February 2005

AbstractThe kidney of Diceros bicornis has about 60 lobes, all appearing peripherally. These are separated by interlobar septa, except for small septal defects through which tubules pass. Renal capsule and interlobar septa are fibromuscular and contain small blood vessels. The kidney is about 65% cortex. It contains about 12.5 × 106 glomeruli, which form about 7% of the cortical mass and 4.6% of the renal mass. Diameter of a glomerular capsule is about 244 μm, there being no difference in size across the cortex in these adults. The ureter bifurcates into a cephalic and a caudal, fibromuscular, urothelial‐lined conduit, into which open about 23 urothelial‐lined infundibula. The common large collecting duct, or tubus maximus, of every lobe opens at the apex of its infundibulum. Two tubi may join into one infundibulum. The tubi and their terminal collecting ducts (of Bellini) are part of the inner medulla. Musculature of conduits and infundibula is largely longitudinal. The calyx may be represented by a circular muscle bundle near the apex of every infundibulum. The large intralobar veins are partly adherent to their infundibulum and calyx and receive arcuate veins via valved orifices. Most branches of the renal artery enter via the interlobar septa. Within a septum they branch again and also supply numerous perforators, which thence enter the cortex. Remaining branches of the renal artery enter cortex directly from without. A fibromuscular scaffolding lies deep to arcuate veins where they contact medulla. Where these veins contact cortical tubules; however, their walls become merely endothelium, like the walls of the interlobular veins.
Quantitative changes in steroidogenic organelles in the corpus luteum of the pregnant rat in relation to progestin secretion on day 16 and in the morning and afternoon of day 22
Authors: Dharmarajan A. M. , Bruce Neville W. , Waddell Brendan J. 
Published: February 2005

AbstractThe present study was carried out to determine whether the major steroidogenic organelles of luteal cells quantitatively reflect variations in ovarian steroid secretion rates during pregnancy in the rat. Assessments were made on day 16 and in the morning (AM) and afternoon (PM) of day 22 (term is day 23). Ovarian steroidogenesis differs both quantitatively and qualitatively between these stages of pregnancy, so together they provide an ideal physiological model to study structural‐functional relationships in the ovary. Corpora lutea of five rats were examined at each stage after progesterone and 20α‐hydroxypregn‐4‐en‐3‐one (20α‐OHP) secretion rates had been determined by a venous outflow technique. Total progestin secretion (progesterone plus 20α‐OHP) fell from 32.5 ± 5.2 to 9.8 ± 1.2 μg/hr per ovary (mean ± SEM) between day 16 and day 22 AM but then increased to 22.6 ± 1.4 μg/hr per ovary by day 22 PM. The total volume of luteal cell cytoplasm was slightly greater at day 22 AM and PM than at day 16. Similarly, the volumes of smooth endoplasmic reticulum (SER), lipid droplets, and membrane‐bound granules all increased, but the volume of mitochondria decreased slightly. In contrast, the surface areas of SER and the inner and outer mitochondrial membranes did not change between day 16 and day 22 AM but then increased substantially by day 22 PM. Therefore, steroid secretion rates per unit area of steroidogenic membrane showed no consistent pattern over the stages examined. Thus these data do not support the existence of a consistent structural‐functional relationship over the normal range of secretory activity in the rat corpus luteum. It is likely that a number of factors, including a variable reserve capacity for steroidogenesis and secretion of nonsteroid hormones, contribute to this inconsistency.
Fine structural changes and lysosomal phosphatase cytochemistry of ameloblasts associated with the transitional stage of enamel formation in the rat incisor
Authors: Salama Ahmed H. , Zaki A. E. , Eisenmann Dale R. 
Published: February 2005

AbstractTrimetaphosphatase (TMPase) and cytidine‐5′‐monophosphatase (CMPase) were used as lysosomal markers in the transitional ameloblasts (TA) to investigate the distribution of lysosomal structures and to correlate the cytochemical findings with the ultrastructural features of these cells. Of particular interest were the cytochemical and morphological changes which occur as the ameloblasts approach the maturation stage of enamel formation. The sequence of changes observed provides a basis for designation of three regions of the transitional zone (early and late TA and modulating ameloblasts). In the early TA region, the cells decreased in height and contained phagic vacuoles as well as numerous TMPase and CMPase reactive structures. Late transitional ameloblasts had invaginations at their distal ends as well as membrane‐bound structures, both filled with fine granular material. Dense bodies, phagic vacuoles, and other elements of the lysosomal system were enzyme reactive. Modulating ameloblasts lacked the phagic vacuoles but exhibited large numbers of multivesicular bodies, vesicles, and secretory granules. Their distal ends were morphologically altered indicating a change towards ruffle‐ or smooth‐ended varieties of maturation ameloblast. In the former, increased granular material was observed within cell membrane invaginations and associated membrane‐bound structures. In the latter, intercellular spaces widened and were filled with granular material. The present cytochemical findings of an extensive lysosomal system in transitional ameloblasts confirm the function of those cells in reducing the secretory ameloblast population and in the selective elimination of their protein‐synthesizing organelles. Furthermore, this extensive lysosomal system and the present morphological findings are consistent with a potential role for transitional ameloblasts in contributing to the marked loss of enamel protein known to occur during maturation.
Post‐hatching development of the thymic epithelial cells in the rainbow trout Salmo gairdneri: An ultrastructural study
Authors: Castillo A. , López‐Fierro P. , Zapata A. , Villena A. , Razquin B. 
Published: February 2005

AbstractThis study reports the ultrastructure of subpopulations of epithelial cells of the thymic parenchyma during the post‐hatching development of the rainbow trout, Salmo gairdneri, kept at 14°C. At hatching, the thymus contained a small number of medium and large thymocytes interspersed among three different types of epithelial cells: (1) epthelial cells adjacent to the connective tissue capsule; (2) ramified dark epithelial cells with electron‐dense cytoplasm; and (3) pale electron‐lucent epithelial cells displaying secretory‐like features. All these cell types were anchored to one another by desmosomes and had apparently differentiated from the pharyngeal epithelium. At 4 days after hatching, the thymus enlarged, and numerous gaps occurred between the cell processes of contiguous epithelial cell processes of contiguous epithelial cells adjacent to the capsular connective tissue. In 21‐day‐old trout, thymic trabeculae developed carrying blood vessels, and a subcapsular zone became evident containing lymphoblasts and large subcapsular epithelial cells. In 30‐day‐old trout, an outer thymic zone developed consisting of spindle‐shaped epithelial cells which formed a dense network. At this stage, scattered cystic cells, which apparently differentiated from the pale epithelial cells, were present.
Dermal ridge development on the volar pads of the rat (Rattus norvegicus) and comparative study of pattern formation using inbred strains
Authors: Okajima M. 
Published: February 2005

AbstractThe development of dermal ridges, ridge configurations, and volar pad contours was investigated in the volar skin of the rat (Rattus norvegicus). The ridged structures corresponding to the epidermal ridges of primates exist only at the epidermal‐dermal junction in the rat. Dermal specimens were prepared by treatment with alkaline solution and examined by toluidine blue staining and scanning electron microscopy, together with histological sections. Differentiation of dermal ridges began on day 18 of gestation on the palm followed by the sole. Ridges incresed in number with advancing age. The process was complete approximately 2–3 days after birth, and sweat ducts began to develop simultaneously. As dermal ridges present various configurational patterns on palmar interdigital pad III, pattern formation on this pad was inspected in fetuses of three inbred strains possessing different pattern types, and in the hybrid progeny derived from them. Patterns and pad forms appeard to be under genetic control. It was revealed that the ridge arrangements, i.e., whorls, triradii, comb‐like patterns, and others, are closely related to the pad contours during the developmental period, as hypothesized in primates.
Morphometric analysis of capillary geometry in pigeon pectoralis muscle
Authors: Mathieu‐Costello Odile 
Published: February 2005

AbstractThe objective of the study was to examine the relationship(s) between the size and the geometry of the capillary network in the flight muscle of pigeon (Columbia livia). To this end, we used morphometry to analyze the degree of anisotropy (i.e., orientaion) of capillaries with respect to the axis of the muscle fibers in perfusion‐fixed samples of pigeon pectoralis muscles with large difference in capillary denstiy. Capillary number per fiber cross‐sectional area (range, 1,491–5,680 mm−2) depended on fiber size (aerobic fibers, 304–782 μm2; glycolytic, 1,785–2,444 μm2), as well as sarcomere length (1.69–2.20 μm), and the relative sectional area of aerobic and glycolytic fibers (aerobic, 42–84% of total fiber area). The degree of tortuosity of capillaries, i.e., their bending or sinuosity relative to the muscle fiber axis, was primarily a function of sarcomere length. In spite of large differences in capillary density, capillary orientation at a given sarcomere length was remarkably similar among samples. In addition to capillaries running parallel to the muscle fiber axis, a unique arrangement of branches running perpendicular to the muscle fiber axis was found in all samples. This arrangment yielded a large circumferential distribution of capillary surface around the muscle fibers. Compared to mammalian limb muscles examined over a 10‐fold range of capillary density (rang, 450–4,670 mm−2), the degree of anistropy of capillaries was greater in all samples of pigeon M. pectoralis. In the pigeon, there was no increase in the amount of capillary surface area available for exchange per microvessel as a result of a greater degree of capillary tortuosity in samples with larger capillary density (capillary number per fiber cross‐sectional area> 4,000 mm−2), as compared to samples with a capillary density <4,000 mm−2.
Studies of hamster cardiac myofibrillogenesis in vivo with Antibodies to spectrin, desmin, and alpha‐actinin
Authors: Messina Dino A. , Lemanski Larry F. 
Published: February 2005

AbstractThe spectrins are a family of cytoskeletal‐membrane proteins that have generated much interest in the past decade. In the present study, we utilized immunohistochemical, morphological, and electrophoretic techniques to assess the possible function(s) of spectrin in mammalian cardiac tissue during development. Antibodies generated against alpha‐actinin and desmin were also employed to identify myofibrils and intermediate filaments in relation to changes in the distribution of spectrin. Spectrin is localized along the sarcolemma of pre‐myofibrillar hamster cardiac myocytes (day 8, postcoitum) and remains associated with the cell membrane throughout development. The staining pattern is somewhat diffuse at first, but eventually the cell margin becomes clearly defined by day 13 postcoitum. A second, more profound change in the distribution of spectrin occurs during the newborn stage, when spectrin begins to appear in the sarcoplasm. It appears as regularly speced invaginations that are diffuse at first, eventually attaining a position around the Z‐bands of adult muscle. The change in the distribution of spectrin coincides temporally with the appearance of T‐tubules, which are sarcolmmal invaginations that reside at the Z‐bands of adult heart. Thus, spectrin may act as a guidance mechanism for the proper postioning of T‐tubules around the Z‐discs of mammalian cardiac tissue. Although spectrin does not appear to interact directly with early myofibrils it may assist in the proper alignment of T‐tubules and, in doing so, act to stabilize the entire contractile apparatus by enveloping it and attaching it to the sarcolemma.