bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of rabbit collecting duct
Authors: LeFurgey Ann , Tisher C. Craig 
Published: February 2005

AbstractRecently the assumed structural and functional homogeneity of the collecting duct (CD) has been questioned. The objective of this study was to determine if heterogeneity occurs in luminal surface membrane structure or in cytoplasmic configuration of cells in the collecting duct or both. Straight segments of cortical and medullary CD were examined in perfusion‐fixed rabbit kidneys with scanning electron microscopy (SEM), light (LM) and transmission electron microscopy (TEM). Principal cells were the most abundant cells in all CD regions; intercalated cells comprised 37% of the cell population in the cortex, 18% in the outer medulla, and < 1% in the inner medulla. SEM revealed two surface patterns among the ciliated principal cells: 1, located in the cortex and outer medulla, with few surface microvilli, and 2, located in the inner medulla, with abundant microvilli. Intercalated cells exhibited four distinctive luminal surface configurations: I, numerous short microvilli; II, both short and elongate microvilli; III, microplicae alone; and IV, both microvilli and microplicae. Intercalated cells with patterns I and II were predominant in the cortex, while cells with patterns III and IV were most common at the corticomedullary junction. TEM confirmed that marked variation existed in cytoplasmic structures of both principal and intercalated cells. These findings may either indicate the presence of several specific types of principal and intercalated cells or reflect different functional states of the principal and intercalated cells. Regardless of their significance, their presence must be considered in studies seeking to establish precise structural‐functional relationships in this region of the rabbit renal tubule.
Reduced cell proliferation in fetal lung after maternal administration of pilocarpine. A scintillation autoradiographic study
Authors: Smith Dennis M. , Shelley Sue A. , Balis John U. 
Published: February 2005

AbstractFetuses were obtained on the 28th gestational day from pregnant New Zealand white rabbits treated daily, on the 24th through the 27th gestational day, with pilocarpine HCl, 5 mg/kg in saline, or saline alone. Lung fragments from these fetuses were incubated for two hours in medium containing 3H‐thymidine. Scintillation autoradiography of 1‐μm‐thick sections of these fetal lungs revealed that the lung tissue from pilocarpine‐treated fetuses had significantly lower labelled cell indices for both alveolar epithelial cells and interstitial cells. These results indicate that pilocarpine treatment promotes differentiation of immature cells in the fetal lung at the expense of cell proliferation.
Structure of the endodermal epithelium of the chick yolk sac during early stages of development
Authors: Mobbs Ian G. , McMillan Donald B. 
Published: February 2005

AbstractThe structure of the areas pellucida and vasculosa of the early chick embryo (stages 11–29) was examined by light, transmission and scanning electron microscopy. The most striking feature of the endodermal cells of these areas is the presence of large intracellular yolk drops which are characteristic of the regions in which they are found: lipid‐like homogeneous drops in the area pellucida, heterogeneously composed pleomorphic drops in the mid‐region of the area vasculosa and granular drops at the periphery of the area vasculosa in the region of the sinus terminalis. On morphological criteria it is postulated that granular drops may arise by direct engulfment of extracellular yolk, but this does not appear to be true for pleomorphic or homogeneous drops. Since the apical junctions between endodermal cells across the yolk sac are tight, they seal off the extraembryonic compartment from the vitelline circulation and presumably prevent intercellular passage of the yolk constituents. Thus the endodermal epithelium must mediate the transport of nutrients from the yolk mass to the developing embryo. Endodermal cells exhibit a variation across the yolk sac in the presence and number of structures associated with uptake of extracellular materials. The mid‐region of the area vasculosa appears to be the most endocytotically active region with an abundance of microvilli, bristle‐coated pits and vesicles and apical canaliculi and vacuoles. There is a close association between the endoderm and vitelline blood vessels and this association is maintained, as the yolk sac develops, by the formation of small vessels juxtaposed between the vascular surface of the endoderm and the walls of the large vitelline vessels.
Maturation of rabbit auricular chondrocytes grown in vitro in monolayer culture
Authors: Moskalewski S. , Adamiec I. , Gołaszewska A. 
Published: February 2005

AbstractChondrocytes isolated from auricular cartilage of 7‐day‐old rabbits were grown in vitro until the onset of phase III, occurring after 10‐14 population doublings (PD). The size of cells and their dry mass were measured at various PD levels. These data were compared with results of analogous measurements of chondrocytes freshly isolated from 28‐day‐old rabbits.Both in vivo, during cartilage growth, and in vitro, some of the chondrocytes increased considerably in size and acquired two nuclei.Chondrocytes cultured in vitro for 4 population doublings were still capable of depositing elastic fibers in culture and forming cartilage after intramuscular transplantation. After longer periods of cultivation the ability of cells to produce a cartilage matrix declined.It is suggested that the auricular chondrocytes may represent a convenient model for comparative studies of cell aging in culture and in vivo, owing to the simplicity of matching senescent cells arising in both these situations.
Ultrastructural organization of the hamster renal pelvis
Authors: Lacy Eric R. , Schmidt‐Nielsen Bodil 
Published: February 2005

AbstractThe renal pelvis of the hamster has been studied by light microscopy (epoxy resin sections), transmission electron microscopy, and morphometric analysis of electron micrographs. Three morphologically distinct epithelia line the pelvis, and each covers a different zone of the kidney. A thin epithelium covering the outer medulla (OM) consists of two cell types: (1) granular cells are most numerous and have apically positioned granules which stain intensely with toluidine blue, are membrane‐bound, and contain a fine particulate matter that stains light grey to black in electron micrographs. (2) Basal cells do not have granules, are confined to the basal lamina region, and do not reach the mucosal epithelial surface. The inner medulla (IM) is covered by a pelvic epithelium morphologically similar to collecting duct epithelium of IM. Some cells in this portion of the pelvic epithelium (IM) stain intensely dark with toluidine blue, osmium tetroxide, lead, and uranyl acetate. Transitional epithelium, which separates cortex (C) from pelvic urine, has an asymmetric luminal plasma membrane and discoid vesicles, each of which is similar to those previously observed in mammalian ureter and urinary bladder epithelia. Based on morphological comparisons with other epithelia, the IM and OM pelvic epithelia would appear permeable to solutes and/or water, while the transitional epithelium covering the C appears relatively impermeable. It would also appear that the exchange of solutes and water between pelvic urine and OM would involve capillaries, primarily, since morphometric analysis showed that both fenestrated and continuous capillaries of the OM were extremely abundant ( > 60% of OM pelvic surface area) just under the thin pelvic epithelium.
Neuronal‐vascular relationships in the raphe nuclei, locus coeruleus, and substantia nigra in primates
Authors: Felten David L. , Crutcher Keith A. 
Published: February 2005

AbstractA fluorescence histochemical and electron microscopic study of the monoaminergic cell groups in the squirrel monkey and Rhesus monkey brains has revealed the direct apposition of blood vessels to perikarya and dendrites of monoaminergic neurons. Capillaries and small arterioles or venules, ranging from 8–50 μm in diameter, showed perikarya and dendrites abutting the basement membrane without evidence of glial interposition. This neuronal‐vascular relationship was present in 20% to 30% of the small vessels in the serotonergic nuclei raphe dorsalis and centralis superior and in the nor‐adrenergic locus coeruleus. Such contacts were clearly present but observed less frequently in the dopaminergic substantia nigra pars compacta and in the serotonergic nuclei raphe obscurus, pallidus, magnus, and pontis. We postulate that monoamine‐containing neurons apposed to blood vessels in certain regions of the brain may be influenced directly by hormones or other substances in blood.
Complex carbohydrates of rat tracheobronchial surface epithelium visualized ultrastructurally
Authors: Spicer S. S. , Mochizuki I. , Setser M. E. , Martinez J. R. 
Published: February 2005

AbstractApplication of cytochemical methods for complex carbohydrates at the light and electron microscopic levels served further to differentiate secretory cells of the rat tracheobronchial surface epithelium into serous and mucous categories, and permitted subclassification of serous cells into four types and of mucous cells into three types. The granules in different serous cells and Clara cells varied in staining with the periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) method, but generally lacked dialyzed iron (DI) affinity and apparently contained neutral glycoprotein. However, in some focal areas, serous and Clara cell granules showed a pattern of DI staining similar to the PA‐TCH‐SP reactivity. The PA‐TCH‐SP and DI methods stained granule glycoconjugate comparably in the three mucous cell types. The lack of high iron diamine (HID) affinity in these sites testified to carboxylated, periodate‐reactive mucosubstance, presumably sialylated glycoprotein. The luminal surface of the apical plasmalemma of all surface epithelial cells stained with DI but lacked HID affinity. The PA‐TCH‐SP technique stained the surface of the apical plasmalemma of mucous cells, serous cells, and Clara cells in decreasing order of intensity. Microvilli of ciliated cells were PA‐TCH‐SP‐positive, but cilia were unreactive and apparently contained a glycosaminoglycan rather than the presumed sialylated glycoprotein of the other surfaces. DI and PA‐TCH‐SP reactivity of the apical far exceeded that of the basolateral plasmalemma in all surface epithelial cells. Two strata, presumed to be the lamina lucida and the lamina diffusa of the basement membrane under all the surface epithelial cells, stained with the DI but not the PA‐TCH‐SP method and apparently contained glycosaminoglycan. Intraepithelial cells, interpreted as globule leukocytes, appeared to represent mast cells infiltrating the epithelium and carrying out endocytic activity.
Ultrastructural studies on migrating epidermal cells during the wound healing stage of regeneration in the adult newt, Notophthalmus viridescens
Authors: Repesh Lillian A. , Oberpriller Jean C. 
Published: February 2005

AbstractThe ultrastructure of the epidermal cells which migrate over the wound surface of the amputated limb of the adult newt, Notophthalmus viridescens, was observed with transmission (TEM) and scanning (SEM) electron microscopy. In order to aid in the visualization of polyanionic surface materials on the wound epithelium and wound surface with TEM, the basic dye, ruthenium red, was introduced into the fixatives and buffer. Control limbs were processed without ruthenium red. Shortly after amputation, basal cells at the wound margin possessed elongated, flattened profiles with long pseudopodial projections (lamellipodia and filopodia) that appeared to make contact with the fibrin exudate covering the stump tissues. Epidermal cells proximal to the site of amputation were also in a state of mobilization. Large intercellular spaces and a reduction in the number of desmosomes were observed in the migrating cells. Epidermal cell nuclei became characteristically euchromatic with well‐developed nucleoli. Microfilaments were seen within the cytoplasm, extending toward the plasma membrane of cellular processes. Phagocytosed material was also present in the migrating cells. By approximately 9 hours post‐amputation, wound closure was complete, and the wound epithelium consisted of three to four cell layers of a non‐cornified epidermis. Generally, the amount of extracellular material present on the surface and in the enlarged intercellular spaces of migrating epidermal cells remained the same throughout the period of wound closure. A layer of polyanionic material was observed consistently over the fibrin meshwork covering the wound surface with TEM.
The stem‐cell zone of the small intestinal epithelium. V. Evidence for controls over orientation of boundaries between the stem‐cell zone, proliferative zone, and the maturation zone
Authors: Bjerknes Matthew , Cheng Hazel 
Published: February 2005

AbstractWe studied, in mouse jejunum, the possibility that coordinate systems related to crypt axis or muscularis mucosae have an influence over the orientation of the boundaries between three crypt compartments: the stem‐cell, the proliferative, and the maturation zones. Segments of jejunum, from male Swiss albino mice injected with 3H‐thymidine 1 hour before death, were collected, embedded in Epon, and 1‐μm‐thick serial sections were prepared and radioautographed. Similar material was also obtained from an experimental preparation in which the anti‐mesenteric border of a short segment of jejunum was involuted surgically, thus creating a fold similar to the plicae circulares in the human intestine. The crypts lining the sides and top of the folds were greatly tilted, relative to the muscularis mucosae 2 weeks after surgery. The angle formed between the crypt axis and the plane of the muscularis mucosae (Θ) was measured. This was related to the angle formed between the crypt axis and the 3H‐thymidine‐labeled leading edge (β), and that between the crypt axis and the upper boundary of the Paneth‐cell distribution (α). The angle α indicates the orientation of the boundary between the stem‐cell and proliferative zones, while β indicates the orientation of the boundary between the proliferative and maturation zones. We found that β remained perpendicular to the crypt axis for all degrees of crypt tilt (Θ). In contrast, α did not remain perpendicular to the crypt axis over all degrees of crypt tilt. When crypts were tilted by more than 30°, α reoriented and was found to be parallel to the plane of the muscularis mucosae. However, in crypts tilted less than 30°, α remained perpendicular to the crypt axis. We concluded that there are probably two coordinate systems that provide information to the crypt epithelium. The first is a coordinate system related to crypt axis that influences the orientation of the boundary between the proliferative and maturation zones and the second is related to muscularis mucosae an influences the orientation of the boundary between the stem‐cell and proliferative zones. The latter has a threshold of about 30°, which probably represents the range of peristalsis‐induced crypt tilt.
Development of the outflow tract and closure of the interventricular septum in the normal human heart
Authors: McBride Robert E. , Moore G. William , Hutchins Grover M. 
Published: February 2005

AbstractThe majority of congenital heart malformations in humans involve defects in the atrioventricular valves, the crest of the interventricular septum, and/or the outflow tract, but the position and timing of these structures during cardiac development is controversial. We examined all 622 staged, serially sectioned normal human embryos and fetuses in the Carnegie Embryological Collection, and obtained a statistical tabulation of the appearance of the endocardial cushion components and surrounding structures for 382 embryos in good condition between stages 9 and 23 inclusive, when the heart normally develops. Accurately scaled drawings of ventral and lateral views of the hearts of seven embryos from stage 13 through 22 were prepared from graphic reconstructions in order to visualize the relationships of the structures under consideration. We found that development of the outflow tract septum follows the apparent functional separation of both the left and right ventricles and the blood streams leaving them. Elevations of the endocardial cushion material are continuous throughout the outflow tract and develop as a consequence of the elliptical configuration imposed on the circular cross section of the outflow tract. The membranous interventricular septum is formed of cushion material in the space bounded by the outflow tract septum, interventricular septum, and the fused AV cushion and right outflow tract cushion. The results of this study are consistent with the assertion that functional separation of the aortic and pulmonary outflow tracts precedes anatomic septation, and that anatomic septation is brought about by mechanical modeling of developing myocardium and endocardial cushion material.
Adipocyte development in the rat hypodermis
Authors: Hausman G. J. , Campion D. R. , Richardson R. L. , Martin R. J. 
Published: February 2005

AbstractThe relationship between hair‐follicle development and adipocyte formation in the rat hypodermis was studied. Skin samples from rats of various body weights were prepared for histological, histochemical, and electron microscopic analysis. Adipocyte formation in the rat hypodermis was linked spatially and temporally with hair‐follicle growth and development. Cells trapped along the invading edge of hair follicles developed into adipocytes after the descent of the follicles through the dermis. Histochemical characteristics of the outermost cells of hair follicles indicated hypoxic conditions. These conditions may have directed a vascularization process that resulted in a network of adipocytes and capillaries around these follicles. Thus, under normal conditions, adipocyte formation is an integral phase of hair‐follicle development in the rat.
Periarterial macrophage sheaths (Ellipsoids) in cat spleen—an electron microscope study
Authors: Blue Julia , Weiss Leon 
Published: February 2005

AbstractPeriarterial macrophage sheaths (PAMS), a term we introduce to replace “ellipsoids,” surround arterial capillaries in the red pulp of the spleen and are major sites for clearance of blood‐borne particles. PAMS and their arterial capillaries in cat spleens in various states of congestion and contraction were studied by transmission electron microscopy. Thorotrast, a colloidal suspension of thorium dioxide, was injected to label macrophages.A PAMS consisted of a fine meshwork of reticular cells and reticular fibers which held macrophages and formed a cylindrical sheath around an arterial capillary lying in its longitudinal axis. Some PAMS were spongy due to loosening of cell associations by plasma infiltration; others were tightly compressed. Blood cells were both free in the interstices of the PAMS and attached to macrophages.Reticular cells formed a closely applied but incomplete layer adventitial to the arterial capillary and extended branches which contributed to the meshwork. Small villous processes on the major branches of reticular cells approached each other, sometimes forming intercellular junctions, and fit into complementary indentations in the surfaces of macrophages and endothelial cells. Thin filaments within reticular cells filled the villous processes and formed a border beneath the plasmalemma; intermediate filaments ran through the centers of the branches. Reticular fibers lay between reticular cells. Basement membrane fabricated of the same material as reticular fibers lay between the endothelium and reticular cells. Macrophages contained Thorotrast and abundant debris of phagocytized cells and were joined by extensive interdigitation of micropseudopodia. Endothelial cells were long rods which lay parallel and were joined along their bases by interdigitating lateral processes. Intercellular junctions were present at some points, but at others lateral processes were everted to form open interendothelial slits through which blood cells could pass. Endothelial cells possessed great numbers of randomly oriented intermediate filaments and small patches of thin filaments scattered along the basal plasmalemma and in lateral processes. Thin filaments may function to attach cells to one another and to the basement membrane and may assist in closing interendothelial slits. We believe that the endothelium responds to changes in arterial blood pressure and blood flow. It stretches to allow dilatation and recoils, probably due to the intermediate filaments, squeezing blood cells through interendothelial slits.
Scanning electron microscope studies of the auditory papillae of some iguanid lizards
Authors: Miller Malcolm R. 
Published: February 2005

AbstractThe papillae basilares of 16 species (10 genera) of iguanid lizards were studied by scanning electron microscopy. Variations in the surface structures of the auditory papillae showed the following major differences: (1) papillae with localization of the unidirectional hair cells at the apical end of the papilla (Anolis carolinensis); (2) papillae with absence or loss of a portion of the apical bidirectional hair‐cell segment (Basiliscus basiliscus); (3) papillae with a central, short‐ciliated, unidirectional hair‐cell segment, and 3–6 irregular rows of long‐ciliated bidirectional hair cells located in the apical and basal regions (Iguana iguana, Crotaphytus collaris, C. wislizeni, Dipsosaurus dorsalis, Sauromalus obesus); (4) papillae in which the apical and basal bidirectional hair‐cell segments are reduced to two rows of hair cells (Sceloporus occidentalis, S. clarki, S. orcutti, S. jarrovi, S. undulatus, S. magister, Callisaurus draconoides, Uta stansburiana).The above differences in auditory papilla structure agree closely with other anatomical differences that delineate iguanid assemblages. Thus the species in the four groups above fall respectively into the following iguanid groups: (1) anolines, (2) basiliscines, (3) iguanines, and (4) sceloporines.
Morphodynamics of outgrowths of mouse trophoblast in the presence and absence of a monolayer of uterine epithelium
Authors: Van Blerkom Jonathan , Chavez Daniel J. 
Published: February 2005

AbstractMouse blastocysts were cultured in the presence and absence of a confluent uterine, luminal, epithelial monolayer in order to assess (1) comparative developmental abilities and (2) the existence and nature of embryo‐uterine intercellular contacts. Embryonic development and mural trophoblast outgrowth were examined by light, transmission and scanning electron microscopy, and by time‐lapse cinematography. The results demonstrate that cultured mouse blastocysts are capable of development that is essentially equivalent to the early egg cylinder stage in the presence and absence of a uterine epithelial substratum. Penetration of the endometrium and displacement of uterine luminal epithelial cells in vivo is paralleled in vitro by the displacement of uterine cells from the advancing edge of outgrowing mural trophoblast. The ability of mural trophoblast to continue to outgrow and displace uterine cells persists for a finite period of time. The findings are discussed with respect to (1) the nature of embryo‐uterine contact in vivo and (2) mechanisms proposed to explain trophoblastic displacement of uterine luminal epithelial cells during normal implantation.