bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and histochemical aspects of epidermis development of fetal porcine skin
Authors: Meyer Wilfried , Görgen Sabine , Schlesinger Christa 
Published: February 2005

AbstractEpidermal development of fetal porcine skin was studied in fetuses from 41 days of gestation until birth with scanning and electron microscopy techniques as well as histochemical methods, including immunohistochemistry. The porcine fetus develops a relatively thick and solid multilayered cover of epidermal cells, which is not lost before birth. It consists of tightly packed cells of the periderm and the stratum intermedium. The periderm cells are totally filled with filamentous proteins; in the intermediate cells, the filamentous proteins are concentrated in the cell periphery, forming a thick marginal zone. Immunohistochemically, the cytofilaments could be identified as cytokeratins of lower and higher molecular weights. The first thin stratum corneum lamellae are formed below the stratum intermedium at about 80–85 days of gestation.
Immunocytochemical analysis of prolactin cells in the adult rat adenohypophysis: Distribution and quantitation relative to sex and strain
Authors: Phelps Carol J. 
Published: February 2005

AbstractProlactin immunocytochemistry was conducted (1) in serial sections of whole fixed pituitaries, for cell distribution analysis; and (2) on preparations of enzymatically dispersed anterior pituitary cells maintained for 1–4 days in vitro, for quantitation of the relative population of prolactin (PRL) cells. Both types of analysis were conducted on glands from young adult rats of both sexes in Long‐Evans, Sprague‐Dawley, and Fischer 344 strains. Cell quantitation results were compared with serum levels, intracellular content, and in vitro release of prolactin, for individual cell preparations. The results show that both PRL cell distribution and relative population numbers are similar between sexes in all three rat strains. Average percentages ranged from 25.9% to 32.1% in all young males and diestrous females. Prolactinpositive numbers of cells correlated positively with intracellular hormone content but not with serum or medium PRL levels. The prolactin cell population was significantly larger in aged Fischer 344 males but was not correlated with intracellular PRL levels. The prolactin cell population was heterogeneous in staining intensity and distribution in both sexes of all three strains.
Tridimensional structure of the Golgi apparatus in type A ganglion cells of the rat
Authors: Rambourg A. , Clermont Y. 
Published: February 2005

AbstractThe three‐dimensional structure of the whole Golgi apparatus and of its components in type A ganglion cells was examined in thin and thick sections by low‐ and high‐voltage electron microscopy. At low magnification, in 10‐μm‐thick sections of osmicated cells, the Golgi apparatus formed a broad, continuous perinuclear network. At higher magnification and in thinner sections of cells impregnated with uranyl acetate‐lead‐copper citrate or postfixed in K‐ferrocyanide‐reduced osmium, the Golgi apparatus appeared as a heterogeneous structure in which saccular regions characterized by stacks of saccules alternated with intersaccular regions made up of branching membranous tubules which bridged the saccules of adjacent stacks. The saccular regions consisted of the following superimposed elements: (1) a cis‐osmiophilic element made up of anastomosing tubules; (2) two or three saccules negative for the phosphatases tested (i.e., nicotinamide adenine dinucleotide phosphatase = NADPase, thiamine pyrophosphatase = TPPase, and cytidine monophosphatase = CMPase); (3) two saccules showing TPPase activity; and (4) one to three trans‐sacculotubular elements showing a “peeling‐off” configuration, one of which showed CMPase activity. The saccules (phosphatase‐negative) on the cis‐side of the Golgi stacks showed, in addition to small circular pores, larger perforations in register. The cavities thus formed in the stacks of saccules, called “wells,” always associated with small 80‐nm vesicles, had a pan shape with the mouth directed toward the cis‐face and the bottom closed by a TPPase‐positive saccule. In face views of the saccules, the smallest of these perforations showed either a crescent shape, due to the presence of a bud on one side of the perforation, or a circular shape with a single small 80‐nm vesicle in the center which was occasionally attached to the saccule by a filiform stalk. Such smaller cavities were considered as the precursors of the larger perforations and eventually of the wells. The small 80‐nm vesicles seen in the small cavities or in the wells appeared to form in situ and possibly migrate toward the cisternae of endoplasmic reticulum seen proximal to the cis‐face of the stack of saccules. Small 80‐nm vesicles were also numerous in the intersaccular regions, along the lateral‐ and trans‐aspects of the Golgi stacks, while larger, 150‐to 300‐nm vesicles, coated and uncoated, were seen only on the trans‐face of the Golgi stacks in proximity to the trans‐sacculotubular elements which appear to “peel off” from the Golgi stacks.
Association of mesenchyme with attenuated basement membranes during morphogenetic stages of newt limb regeneration
Authors: Neufeld Daniel A. , Aulthouse Amy Lynn 
Published: February 2005

AbstractThe interface between epithelium and mesenchyme may be involved in inductive interactions which occur during development. This interface within the growth bud, or blastema, of a regenerating limb has been examined to determine whether changes in basement‐membrane structures are visible in regions of putative epithelial‐mesenchymal inductive interaction. Regenerating forelimbs of adult newts were fixed by perfusion with osmotically balanced aldehydes. Late‐bulb to early‐digit stage regenerates were collected and processed either for light and transmission electron microscopy or for scanning electron microscopy. Light microscopy confirmed that regions characterized by increased numbers of subepithelial mesenchymal cells were covered by a diffusely stained basement membrane. Transmission electron microscopy of these regions revealed two structural components of the basement membrane. The thin basal lamina was continuous in all regions of all stages examined, but it was attenuated apically in areas of mesenchymal cell accumulation. The thicker underlying reticular lamina was markedly attenuated in these regions near the blastemal apex. Scanning electron microscopy of de‐epithelialized blastemas revealed that, apically, the reticular lamina formed only a delicate lacelike network. On the base of the blastema, it formed a dense fibrillar meshwork which was further organized into a geometric pattern in the adjacent stump skin. Cumulatively, these observations suggest that physical contact between epithelial and mesenchymal cells is not essential at these stages, but that regions of putative epithelial‐mesenchymal interaction are characterized by a distinctly diminished reticular lamina. Structural changes in basement‐membrane components may be related to termination of local inductive events.
The ultrastructure of the rat primary decidual zone
Authors: Parr Margaret B. , Tung H. N. , Parr Earl L. 
Published: February 2005

AbstractThe rat primary decidual zone (PDZ) is a transitory, avascular region of transformed fibroblasts surrounding the implanting embryo. Tracer studies have indicated that the PDZ is selectively permeable to macromolecules, permeability decreasing with increasing molecular weight of the tracer. To clarify the morphological basis of the permeability barrier, we have studied the ultrastructure of the PDZ with particular emphasis on the intercellular features and cellular junctions. The cells of the PDZ were large and tightly packed; their apposed membranes showed extensive interdigitations in some regions, but elsewhere they were relatively straight. Tight junctions, gap junctions, and desmosomelike junctions were observed between decidual cells. The tight junctions usually consisted of one or two points of membrane fusion, and they were oriented both parallel and perpendicular to the long axis of the PDZ. These junctions were frequently associated with gap junctions. Scattered pockets of dilated extracellular space between decidual cells contained collagen fibrils and an amorphous, dense material. These extracellular components were also sequestered by the decidual cells in deep invaginations of the cell surface that were continuous with the extracellular space. Decidual cells also exhibited flangelike processes that penetrated the basal laminae of the adjacent epithelium and capillary endothelium. Our present observations indicate that decidual cells are connected by tight junctions, and a previous study demonstrated that macromolecules up to 40 kDa readily cross the PDZ; hence, the tight junctions appear to be discontinuous. We suggest that the structures restricting the movement of large macromolecules (66 kDa and larger) across the PDZ from blood vessels to the embryo may include discontinuous tight junctions, membrane interdigitations, and amorphous intercellular material.
The structure of the osteoderms in the gekko: Tarentola mauritanica
Authors: Levrat‐Calviac V. , Zylberberg L. 
Published: February 2005

AbstractHistological and cytological analysis reveals that the osteoderms of Tarentola mauritanica are composed of an outer part superimposed on a basal region. The structure of both parts can be related to that of the surrounding dermis. The basal part of the osteoderms, inserted in the dense dermis, is made up of abundant closely packed collagen fibrils that orient the mineral deposit. The outer part, located in the superficial loose dermis, is crossed by few bundles of mineralized collagen fibrils arising from the basal part. These bundles connect the osteoderm to the overlying loose dermis. The outer superficial part is characterized by the presence of mineralized globules surrounding the mineralized collagen bundles. In these globules, the crystals are deposited on a microfibrillar matrix rich in acidic mucosubstances and composed of radially oriented, tangled microfilaments that lie among the collagen bundles. The two different mineralizing systems in the osteoderms of Tarentola mauritanica may reflect two different organic matrices. The mineral is deposited in a preexisting dermal tissue, as a “metaplastic ossification,” and is another expression of the potential retained by the reptilian dermis to form mineralized structures.
Development of aortic and mitral valve continuity in the human embryonic heart
Authors: Teal Sharon I. , Moore G. William , Hutchins Grover M. 
Published: February 2005

AbstractThe anatomic relationship of the aortic and mitral valves is a useful landmark in assessing congenital heart malformations. The atrioventricular and semilunar valve regions originate in widely separated parts of the early embryonic heart tube, and the process by which the normal fibrous continuity between the aortic and mitral valves is acquired has not been clearly defined. The development of the aortic and mitral valve relationship was studied in normal human embryos in the Carnegie Embryological Collection, and specimens of Carnegie stages 13, 15, 17, 19, and 23, prepared as serial histologic sections cut in the sagittal plane, were selected for reconstruction. In stage 13, the atrioventricular valve area is separated from the semilunar valve area by the large bend between the atrioventricular and outflow‐tract components of the single lumen heart tube created by the left interventricular sulcus. In stages 15 and 17, the aortic valve rotates into a position near the atrioventricular valves with development of four chambers and a double circulation. In stage 19, there is fusion of aortic and mitral endocardial cushion material along the endocardial surface of the interventricular flange, and this relationship is maintained in subsequent stages. Determination of three‐dimensional Cartesian coordinates of the midpoints of valve positions shows that, while there is growth of intervalvular distances up to stage 17, the aortic to mitral distance is essentially unchanged thereafter. During the period studied, the left ventricle increases in length over threefold. The relative lack of growth in the saddle‐shaped fold between the atrioventricular and outflow tract components of the heart, contrasting with the rapid growth of the outwardly convex components of most of the atrial and ventricular walls, may be attributed to the different mechanical properties of the two configurations. It is postulated that the pathogenesis of congenital heart malformations, which characteristically have failure of development of aortic and mitral valve continuity, may involve abnormalities of rotation of the aortic region or malpositioning of the fold in the heart tube.
Adenohypophysis of the elephant seal (Mirounga leonina): Morphology and seasonal histological changes
Authors: Griffiths D. J. , Bryden M. M. 
Published: February 2005

AbstractChanges in adenohypophyseal cell populations over a 12‐month period were studied in the seasonally breeding elephant seal (24 adult males, 3 adult females, and 5 neonates) at Macquarie Island. The glands were weighed and fixed in formol sublimate. Selected sections were stained with the oxidation‐alcian blue‐periodic acid Schiff‐orange G technique. Gonadotropic, thyrotropic, lactotropic, and somatotropic cells were readily identifiable; whilst corticotropes, inactive secretory cells of all types, and stellate cells were not stained and were counted collectively as chromophobic cells. Hypophyseal weight was low throughout autumn and winter, but increased significantly during the spring breeding season and the summer. Thyrotropes were distributed evenly throughout the pars distalis, but the other secretory cells showed areas of concentration. Acidophils were common peripherally, particularly lactotropes, while gonadotropes were largely confined to the ‘basophilic wedge,’ a narrow, central superior zone. In males, lactotropic and gonadotropic cells showed significant seasonal changes in number. Gonadotropes were more common in sexually active males than sexually quiescent ones, while lactotrope numbers were much greater at midsummer than midwinter. This lactotrope cycle appeared to be related to photoperiod but unrelated to breeding.
Proliferation of arteriovenous anastomoses in the developing rabbit ear is enhanced after denervation
Authors: Morris Judith L. , Bevan Rosemary D. 
Published: February 2005

AbstractThe innervation of the rabbit ear vasculature by noradrenergic and substance P‐immunoreactive (SP‐IR) nerves was investigated in both young and adult animals. All vascular segments were supplied by both noradrenergic and SP‐IR nerves. In the ear margins, the arteriovenous anastomoses (AVAs) were more densely innervated than other vessels. In general, the density of both noradrenergic and SP‐IR nerves increased with age until 10–12 weeks postnatum. The ear vasculature was denervated in young rabbits to test whether the normal proliferation of AVAs in the growing ear was altered in the absence of nerves. Surgical resection of all auricular nerve trunks except the auricular branch of the auriculo‐temporal nerve, and removal of the ipsilateral superior cervical ganglion in 10‐ to 12‐day‐old rabbits left the ear devoid of both noradrenergic and SP‐IR nerves for at least four weeks. Repeated administration of 6‐hydroxydopamine (6‐OHDA) to young rabbits produced degeneration of noradrenergic terminal axons, but preterminal nerve trunks survived. SP‐IR nerves did not appear to be affected by 6‐OHDA. These denervaton regimes resulted in a 1.5‐ to 2‐fold increase in the number of AVAs formed in the growing ear. Surgical denervation and 6‐OHDA treatment also led to retarded growth of the media of the central ear artery, but this effect of 6‐OHDA was probably not due to a specific action on vascular smooth muscle. Surgical resection of most of the dorsal auricular nerves in adult rabbits did not affect AVA density. Large differences in AVA density were apparent between groups of control animals from different parts of the country, or groups examined at different times of the year. These results demonstrate that the labile nature of AVAs in the rabbit ear can result in considerable variability in the absolute number of AVAs and suggest that both intrinsic and extrinsic factors may influence development of the microvasculature.
Somitic‐vertebral correlation and vertebral levels in the human embryo
Authors: Müller Fabiola , O'Rahilly Ronan 
Published: February 2005

AbstractSomitic and vertebral interrelationships and levels were studied in 84 human embryos of stages 9–23 (3–8 postovulatory weeks). The first four somites are occipital, the occipitocervical junction is at somites 4/5, and eight somites are involved in the cervical region: X, Y, Z, and C. 3–7. By stage 17 the total number of occipitovertebral “units,” namely 38 or 39, is attained. Resegmentation (Neugliederung) of sclerotomes is not supported. A new scheme of somitic/vertebral correlation is proposed in which somites and centra are in register. Differential growth of the regions of the vertebral column was calculated, and it was found that the percentages of the total column occupied by the various regions vary from one stage to another. The cervical and coccygeal regions decrease, the thoracic and lumbar regions increase, and the sacral region remains more or less constant during embryonic development. The following structures descend with reference to the vertebral column during the embryonic period proper: roots of lower limbs, thyroid gland and thymus, tracheal bifurcation, lungs, heart, diaphragm, abdominal arteries, mesonephroi, and suprarenal glands. The gonads may descend slightly. The scapulae and the separation point between the trachea and the esophagus remain at a fairly constant level. The metanephroi ascend. The migration of many of these structures (e.g., the heart, diaphragm, and metanephroi) is much more marked in the embryonic period than later although it continues during the fetal and postnatal periods. The conus medullaris ascends during the fetal period. Anomalies of migration that affect such organs as the thyroid gland, gonads, and metanephroi are discussed.
Immunocytochemical localization of a developmentally regulated, isoproterenol‐inducible protein (LM protein) in rat submandibular gland
Authors: Yagil Chana , Naito Yukio , Barka Tibor 
Published: February 2005

AbstractAdministration of the β‐adrenergic drug isoproterenol (IPR) produces hyperplastic and hypertrophic enlargements of the submandibular gland of the rat and induces the synthesis of specific proteins in this organ. One of these proteins, the LM (large mobile) protein, was demonstrated immunocytochemically in the submandibular glands of developing untreated and IPR‐treated rats. Immunoreactive LM protein was absent in the glands of 20‐day‐old fetuses and 1‐ and 2‐day‐old rats. It was localized in the proacinar and immature acinar cells in the glands of 6‐ to 21‐day‐old animals, but it was undetectable at 28 days of age. In the glands of adult rats, secretory granules of the granular convoluted tubule cells showed immunostaining for the LM protein which was also present in trace amounts in the acinar cells. Daily administration of IPR for 5 days to newborn or 8‐ or 15‐day‐old rats caused an apparent acceleration of proacinar/acinar cell differentiation, and consequently it increased the frequency of cells immunostained for the LM protein as well as the amount of immunoreactive material in these cells. Thus, the expression of LM protein in the submandibular gland is developmentally regulated, and it is restricted to the stage of differentiation of proacinar cells from terminal tubule cells. IPR is capable of inducing this protein in fully differentiated acinar cells in 3‐week‐old or older animals.
Restriction of exogenous transthyretin (Prealbumin) by the endothelium of the rat choriocapillaris
Authors: Pino Richard M. 
Published: February 2005

AbstractThe endothelium of the choriocapillaris has been shown to restrict molecules with Einstein‐Stokes radii ≥ 3.2 nm which correspond to minimal molecular weights of approximately 64,000–68,000 daltons. The present study was undertaken to determine if the endothelium restricts exogenous transthyretin (prealbumin), a 55,000‐dalton carrier of retinol‐binding protein. Rats were injected with human 125I‐transthyretin which was allowed to circulate for 15 and 30 min. Chromatographic analysis demonstrated that the human transthyretin did not bind to rat blood proteins. Eye tissue from injected rats was prepared for light and ultrastructural autoradiographic analysis. Autoradiographic grains were confined to areas over the lumen of the choriocapillaris with few present on Bruch's membrane, the basement membrane common to the endothelium of the choriocapillaris and the retinal pigment epithelium. These findings demonstrate that the choriocapillaris can restrict transthyretin and suggest a possible role of its endothelium in the metabolism of retinol‐carrier molecules.
Ultrastructural localization of concanavalin A‐binding sites in the Golgi apparatus of various types of neurons in rat dorsal root ganglia: Functional implications
Authors: Malchiodi F. , Rambourg A. , Clermont Y. , Caroff A. 
Published: February 2005

AbstractThe localization of concanavalin A (con A) binding sites has been determined at the electron‐microscopic level in the six types of neurons (A1, A2, A3, B1, B2, C) of rat dorsal root ganglia. In all ganglion cells, con A stained the plasma membrane, the nuclear envelope, the cisternae of the rough endoplasmic reticulum, and the matrix of some multivesicular bodies. In contrast, the con A reactivity of the Golgi apparatus varied according to cell type. In type B1 and B2 cells and possibly in type A3 cells, the lectin was exclusively located in three or four saccules on the cis side of the Golgi stacks, whereas the TPPase‐positive saccules and the trans sacculotubular elements were unstained with con A. In type A1, A2, and C neurons, all Golgi saccules as well as the trans sacculotubular elements were stained with the lectin. These results suggest that different types of glycoproteins were produced in these two groups of neurons. In the type A1, A2, and C cells, the persistence of the lectin reactivity in the TTPase‐positive saccules or sacculotubular elements on the trans side of the Golgi stacks suggests the presence of glycoproteins with oligosaccharide side chains rich in α‐D‐mannosyl residues in terminal positions. In contrast, the disappearance of the con A reactivity in equivalent elements of the Golgi stacks in type B1, B2, and A3 cells suggests the addition at this level of other sugar residues characteristic of complex oligosaccharide side chains. The majority of the vesicular elements associated with the Golgi apparatus, as well as lysosomes, were unstained with con A.