bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular gene expression for calbidin‐D28k in mouse kidney
Authors: Rhoten William B. , Christakos Sylvia 
Published: February 2005

AbstractGene expression for calbindin‐D28k, the 28,000 relative molecular mass vitamin D‐dependent calcium‐binding protein, was measured in cells of the murine nephron by in situ hybridization on tissue sections (hybridization cytochemistry). Radiolabeled (35S‐UTP), single‐stranded RNA complementary to calbinding‐D28k‐mRNA (probe RNA) was prepared from linearized cDNA template and used for the hybridizations. Autoradiography was carried out and cellular levels of hybridization signal (silver grains) were quantified. After corretion for background the concentration of silver grains was more than 350% greater in the distal tubule than in either the proximal tubule or the glomerulus. The relative cellular level of mRNA in the cytoplasm, as reflected in silver grains/cell, of the distal tubules with probe RNA was 3.4 times greater than that with control RNA. Cells of the distal tubule were the only apparent sites of specific hybridization with probe RNA. The presence of calbindin‐D28k‐mRNA in the distal tubule corresponded to the localizations of calbindin‐D28k by immunocytochemistry.
Anatomy of the pancreas and langerhans islets in snakes and lizards
Authors: Moscona A. A. 
Published: February 2005

AbstractThe pancreas of snakes (18 species) was comparatively examined and classified into five major types, based on structure of the lobes and ducts, spatial relationships with the spleen and the gall bladder, and the disposition of islet cells. These types trend toward fusion of the pancreatic lobes and compaction of the pancreas—a progression that coincides with the phylogeny of the snakes. The more primitive pancreas of lizards (17 species) also was surveyed; that of Varanus is of special interest because its structure is intermediate between the extended, tri‐lobate pancreas of lizards and the compact pancreas of snakes and may represent a transitional link in the evolution of this organ. Islet tissue is always confined to the dorsal lobe and is concentrated in its distal region adjacent to the spleen. In primitive snakes and in Varanus, a large islet mass is sequestered within a distinct juxtasplenic “islet body” distanced from the dorsal lobe and connected to it by a slender stalk. In some of the most advanced snake species, numerous islets of endocrine cells are found within the spleen. The occurrence and formation of these intrasplenic islets is described in detail. The anatomic “affinity” between spleen and the islet region of the pancreas is discussed. A hypothesis for the development of the pancreas from embryonal placodes on the mid‐gut is presented; it proposes that the exocrine and the endocrine components derive from different progenitor cells, and that the endocrine progenitors are located in the center of the dorsal placode. The hypothesis combines embryological and evolutionary views about the origin of the pancreas, and offers a rationale for differences in its structure and in the disposition of the islets.
Endothelial cell division in metaphyseal capillaries during endochondral bone formation in rats
Authors: Hunter William L. , Arsenault A. Larry 
Published: February 2005

AbstractEndothelial cell division in the metaphyseal capillaries of growing rats was studied by serial sectioning and electron microscopic examination. The endothelium of these capillary sprouts forms a continuous attenuated saqmous lining. During endochodral bone formation these growing vessels possess a region of endothelial cell division which is located behind the sprout tip in an area where the microvascular wall consists of an endothelium and a discontinuous layer of perivascular cells. Examination of this region has shown the presence of junctional attachments between daughter cells even before cell separation is complete. Thus, the integrity of the vascular wall is not compromised during cell division. Junctional complexes with adjacent endothelial cells are also formed along the cleavage plane prior to the completion of cytokinesis. Numerous microvilli from both the daughter cells and adjacent endothelial cells often make contact and form junctions with the plasma membrane of the dividing cells. A model for endothelial junction formation between daughter cells during cytokinesis and the role that microvilli play in the process is proposed.
Cortical alveolus breakdown in the eggs of the freshwater teleost Rhodeus ocellatus ocellatus
Authors: Ohta Tadayuki , Iwamatsu Takashi , Tanaka Masako , Yoshimoto Yasuaki 
Published: February 2005

AbstractCortical alveoli and their breakdown in the eggs of the rose bitterling were morphologically investigated. Cortical alveoli of various sizes existed in multiple layers within the cortical cytoplasm of each egg. Two types of cortical alveoli were recognized–one possessed homogeneous contents; the other possessed heterogeneous contents with electron‐less dense spots. The eggs were activated by a penetrating spermatozoon or by immersion in fresh water. The immersion of the eggs into fresh water induced a wave of cortical alveolus breakdown (CABD), which was propagated from the vegetal pole to the animal pole. When eggs were inseminated in fresh water, CABD progressed from both the vegetal and the animal poles of the egg, and was complete within about 20 min. The contents of the cortical alveoli were released into the perivitelline space through a large opening formed by the fusion of the plasma and cortical alveolar membranes. For a short time after CABD, the smooth inner surfaces of the cortical alveoli were readily discernible from the rougher original plasma membrane. About 30 min after immersion in fresh water, the inner surfaces of the cortical alveoli were indistinguishable from the original egg surfaces. Aequorin‐injected eggs became luminescent immediately after their immersion in fresh water. The luminescence reached a maximum level about 15 min later and subsided after roughly 30 min. The result shows that increase in intracellular free Ca ions occurs during CABD.
Pericyte of a teleost fish: Ultrastructure, position, and role in neoplasia as revealed by a fish model
Authors: Couch John A. 
Published: February 2005

AbstractThe morphology and position of the pericyte, a periendothelial cell, is described for a teleost fish, Cyprinodon variegatus. This cell was found attached to the abluminal surfaces of capillaries, venules, and arterioles of the submucosa of the midgut of the fish. The cell was encompassed by a thin basal lamina, possessed numerous plasmalemmal vesicles, a “sole region” which contained thinner actin‐like filaments and possibly thicker myosin‐like filaments, and ranged in form from ovoid to stellate, with long cytoplasmic extensions that partially covered the endothelium of the associated microvessel. The pericyte of C. variegatus has been shown to give rise to hemangiopericytomas (experimentally induced with diethylnitrosamine) and possibly to pericytomas. The range of phnotypic expression of these pericyte‐derived neoplasms is broad, and dependent upon the degree of differentiation of their constituent cells which range from clear cell pericytes to myofilamentous laden cells that resemble smooth muscle cells. In this regard and in regard to its normal ultrastructural morphology, and anatomical position, in relationship to microvasculature in this fish, the cell is very similar to other vertebrate pericytes. Limited evidence suggests that small fish species may be excellent study models for further elucidation of pericyte form, function, and role in disease.
Cholinesterase activity in terminal Schwann cells associated with Ruffini endings in the periodontal ligament of rat incisors
Authors: Maeda Takeyasu , Kannari Koichi , Sato Osamu , Kobayashi Shigeo , Iwanaga Toshihiko , Fujita Tsuneo 
Published: February 2005

AbstractA nonspecific cholinesterase activity was demonstrated in terminal Schwann cells associated with Ruffini endings in the periodontal ligament of rat incisors at the light and electron microscopic levels. The terminal Schwann cells are ultrastructurally characterized by a well‐developed Golgi apparatus and rough endoplasmic reticulum. The cells in this study were positive for nonspecific cholinesterase, whereas ordinary Schwann cells associated with more proximal nerve fibers reacted negatively. The reaction products were densely deposited in the cisternae of the rough endoplasmic reticulum and along the nuclear envelop. A moderately intense labeling was found in the cytoplasmic extensions, in which the reaction products gathered in caveolae and vesicles. These findings indicate that nonspecific cholinesterase is a useful marker to distinguish terminal Schwann cells from ordinary Schwann cells and that the enzyme may be synthesized in the rough endoplasmic reticulum and conveyed toward the axon terminals. Since this enzyme has been known to be shared by the inner bulb of Pacinian corpuscles and the lamellar cells of Meissner's corpuscles, its possible involvement in mechanore‐ceptive functions in these specialized Schwann cells deserves further investigation.
High‐resolution localization of hyaluronic acid in the golden hamster oocyte‐cumulus complex by use of a hyaluronidase‐gold complex
Authors: Kan Frederick W. K. 
Published: February 2005

AbstractThe distribution of hyaluronic acid in the oocyte‐cumulus complexes collected from the oviduct ampulla of superovulated hamsters was revealed by use of hyaluronidase coupled to colloidal gold. On thin sections of Lowicryl‐embedded oocyte‐cumulus complexes, gold particles were associated specifically with interconnecting fibrillar materials that make up the cumulus matrix. Inside the cumulus cells, gold particles were found over the cisternal membrane of the rough endoplasmic reticulum, in the contents of lysosomes and multivesicular bodies, and over Golgi vesicles of some cumulus cells. A high concentration of gold labeling was observed over the peripheral condensed chromatin and perinucleolar components in the nucleus. The cell surface of the cumulus cells also appeared to be labeled. Gold particles, however, were absent over the mitochondria and lipid vacuoles. In the oocytes, labeling was found to be associated mainly with rough endoplasmic reticulum and arrays of lamellar structures; cortical granules, mitochondria, and coated vesicles were essentially devoid of gold particles. Gold particles were also seen along the plasma membrane of the oocytes and within the perivitelline space. The zona pellucida was not labeled by hyaluronidase‐gold. Different control experiments confirmed the specificity of the labeling. Digestion of thin sections with hyaluronidase prior to incubation with hyaluronidase‐gold abolished the initial reaction, whereas treatment of thin sections with chondroitinase did not prevent labeling of oocyte‐cumulus complexes by hyaluronidase‐gold. Although the function of hyaluronic acid in the oocyte‐cumulus complex at the time of ovulation and fertilization is not known, the high concentration of this particular compound in the cumulus matrix and the cumulus cells and its specific locations in the perivitelline space and in the superovulated oocytes implicate the significance of its presence and warrant future investigations.
Calcium in the developing Ambystoma neural axis shown by 3H and fluorescent chlortetracycline and atomic absorption spectrometry
Authors: Moran Denis J. 
Published: February 2005

AbstractThe calcium ion has been implicated in the mediation of the morphogenetic movements that occur during neural tube formation. The present study identifies high levels of calcium in the neuroepithelium of the neural plate, folds, and tube. These levels are substantially higher than those discerned elsewhere in the embryo. The calcium is localized in morphogenetically active regions by using the antibiotic chlortetracycline (CTC) which chelates calcium and is demonstrated in this investigation by both autoradiography and calcium‐linked fluorescence. The specificity of CTC reaction for calcium in the developing neural axis is confirmed by EGTA competition.A comparison of the actual calcium levels in the developing neural axis (dorsal) with equivalently weighted ventral tissues was obtained by atomic absorption spectrometry (AAS). This method provides a total count of the calcium without any loss during tissue processing. For AAS, living tissues were precisely excised and immediately dessicated. Each tissue sample (dry weight 1.5 mg) was then solubilized for analysis. The spectrometric data reveal that the embryonic dorsal aspect forming the neural tube contains 57% more calcium than an equivalent weight of the ventral aspect.
Ectopic colonization of primordial germ cells in the chick embryo lacking the gonads
Authors: Nakamura Masao , Kuwana Takashi , Miyayama Yukihiko , Yoshinaga Kazuya , Fujimoto Toyoaki 
Published: February 2005

AbstractChick primordial germ cells (PGCs) first appear in the extraembryonic region in the early embryo, then temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. In the present study, we examined the trend of ectopic distribution of PGCs in the chick embryo when its future gonadal region had been removed a t an early stage. Embryos at stage 10, from which the caudal third region was excised, were incubated until they reached stages 14 to 20. In embryos at stage 14, about 80% of the total PGCs were found in the capillaries of the yolk sac, whereas others were observed in the head, mainly in the mesenchyme and small vessels close to the neural tube. From stage 18 onward, many PGCs accumulated in the embryo proper; about 90% of them colonized in the head region around the neural tube. These ectopic PGCs in the head were found in the capillaries, sometimes as thrombi or emerging from them into the adjacent mesenchyme. These results show that, when the chick embryo lacked gonads, the PGCs could be concentrated in the head region and migrated from the capillaries into the mesenchyme.
Spatial disorder of collagens in the great vessels, associated with congenital heart defects
Authors: Rosenquist Thomas H. , Módis László 
Published: February 2005

AbstractSurgical ablation of the cardiac neural crest from the chicken embryo results in persistent truncus arteriosus (PTA) and a change in the elastic laminae of the great vessels, wherein elastin and the elastin microfibril show significant spatial disorder. The purpose of this study was to test the hypothesis that the interstitial collagens would also be disordered in the elastic laminae of chicken embryos with PTA. The birefringence characteristics of interstitial collagen were examined to evaluate spatial ordering. The results showed that collagen in the elastic laminae assumed an orderly configuration of well‐defined fiber bundles in the great vessel walls of control embryos, whereas vessels from embryos with PTA lacked any distinct spatial order. Collagens type I and III were localized in the vessel walls. Type III collagen was the principal collagen of the elastic laminae, but was absent from the intima of all vessels. In the elastic laminae of vessels from control embryos, collagen type III showed well‐defined fiber bundles whereas embryos with PTA had diffuse collagen type III in poorly defined laminae that were not separated by discrete layers of smooth muscle cells. Collagen type I was a minor component of the elastic laminae but formed robust pericellular fiber bundles throughout the media and intima. Collagen type I fibers appeared to be coarsened and less uniform in the vessels from embryos with PTA.
Heterogeneity in granulosa cells of developing rat follicles
Authors: Rao I. M. , Mills T. M. , Anderson E. , Mahesh V. B. 
Published: February 2005

AbstractThe present study was designed to characterize the granulosa cell subpopulations derived from rats in which ovarian growth was induced by diethylstilbestrol (DES) or in which growth and differentiation was induced by pregnant mare's serum gonadotropin (PMSG). In the DES model, immature rats were given two separate injections of 2 mg DES/rat s.c. on 25 and 26 days of age and were killed 24 hr after the second injection. In the PMSG model, rats on day 28 were given 8 IU of PMSG s.c. and were killed 54 hr later. Granulosa cells were isolated from the ovaries, separated on a continuous Percoll density gradient, and divided into 12 fractions. The cells in each fraction were cultured in the presence of androstenedione with or without 20 ng/ml of follicle‐stimulating hormone (FSH) and estradiol and progesterone in the incubation medium were measured. In DES‐treated rats, granulosa cells in fractions 4 and 5 and fractions 9 and 10 contained about 30–40% of total cell yield and showed high steroidogenic potential. Granulosa cells from fractions 6, 7, and 8, which represent 55–60% of total cell yield, produced relatively low amounts of steroids on a per‐million‐cell basis. FSH was required for the stimulation of steroidogenesis. In granulosa cells from the PMSG treated rats, aromatase activity appeared maximally induced and incubation with FSH in vitro did not bring about any further increase. However, in vitro incubation with FSH was required for progesterone production. Furthermore, the granulosa cells from the PMSG treated rats also showed much more active estradiol and progesterone synthesis in fractions 9–12 as compared with lower density fractions. These studies suggest functional heterogeneity of granulosa cell populations in their response to FSH‐induced steroidogenesis. In addition, it was observed that in both models, there are two major populations of granulosa cells as evidenced by light and electron microscopy. The functional role of small and large granulosa cells in steroidogenesis is unclear; further studies are in progress.
Bone‐cell changes in estrogen‐induced bone‐mass increase in mice: Dissociation of osteoclasts from bone surfaces
Authors: Liu Chung‐Ching , Howard Guy A. 
Published: February 2005

AbstractEarly studies in certain avian and mammalian species have described estrogen‐associated bone‐cell changes, which were based on bone cells that were neither quantified nor identified histochemically (osteoclasts). In the experiments described here, weanling female mice were given a pharmacological dose of 17β‐estradiol benzoate (1 mg/week) for 1 and 4 weeks, and changes in osteoclasts and osteoblasts were assessed in tibial metaphyses and diaphyses. In the proximal metaphysis, the number of osteoclasts/mm surface length was significantly reduced by estrogen at 1 week (43%) and 4 weeks (64%), which was accompanied by significant increases in the number of osteoclasts in the marrow space not in contact with bone surfaces (no./mm2: 382% and 999%, respectively). These increases, along with observations of decreased osteoclast size (19%), of changes in osteoclast morphology, and of numerous acid‐phosphatase‐positive fragments in the marrow space, suggest that estrogen treatment causes the dissociation and disintegration, and thus decreased activity, of osteoclasts. The above changes were accompanied by more than 48% increases in the number of trabecular osteoblasts. In the diaphysis, the number of endosteal osteoclasts was significantly decreased by estrogen at 1 week (32%), but was not significantly changed at 4 weeks. These changes were attended by significant increases in the number of osteoclasts in the marrow space not in contact with bone surfaces (no./mm2: 393% at 1 week and 342% at 4 weeks). The number of endosteal osteoblasts was also increased by estrogen at 1 week (132%), and so was the size of endosteal osteoblasts (39% at 1 week and 81% at 4 weeks). Comparable results were obtained when a lower dose of 17β‐estradiol benzoate (20 μg/week) was given to ovariectomized mice. The increase in bone mass and its associated cell changes following estrogen treatment were also found in athymic nude mice, suggesting that these bone/bone cell changes are independent of the thymus.
Immunoelectron microscopic study of tyrosine hydroxylase immunoreactive nerve fibers and ganglion cells in the rat adrenal gland
Authors: Oomori Yukio , Okuno Sachiko , Fujisawa Hitoshi , Ono Kazuyuki 
Published: February 2005

AbstractThe present immunocytochemical study used an antiserum to tyrosine hydroxylase (TH), the first enzyme in the biosynthetic pathway of catecholamines, and revealed TH immunoreactivity in the ganglion cells and in the varicose nerve fibers of the cortex and medulla in the rat adrenal gland. TH immunoreactive nerve fibers in the cortex and medulla contained large and small granular vesicles, and also small clear vesicles. The immunoreactive nerve fibers were in close apposition to cortical cells in the cortex and in apposition to smooth muscle cells of blood vessels in both the cortex and medulla. Furthermore, TH immunoreactive nerve fibers were sometimes in close apposition to pericytes of blood vessels in the cortex and chromaffin cells in the medulla. The present results suggest that the catecholaminergic nerve fibers in the rat adrenal gland may be both intrinsic and extrinsic in origin.
Pathways of lymph flow from the intestine of the horse
Authors: Nikles Stephen A. , Heath Trevor J. 
Published: February 2005

AbstractThe intestine of horses differs from that of most other domestic animals in having a huge ascending colon and cecum, which together act as a large fermentation vat. The lymph drainage from this intestine occurs through a complex network of lymph vessels and lymph nodes, of which there are several thousand.The pathways taken by lymph through these vessels and nodes were studied by tracing injections of dye, by examining Microfil casts, and with light and transmission electron microscopy.Lymph vessels transporting lymph from the intestinal wall generally terminate on a single node within a group of primary nodes. Efferent lymphatics form networks in the immediate vicinity of groups of nodes. In these networks, the vessels branch, anastomose, entwine amongst one another, and sometimes form recircu‐lating loops. Usually 2–9 lymphatic vessels course away from these networks to secondary or higher‐order nodes in both local and more central locations. Vessels reaching these nodes generally terminate on more than one node within each group. This pattern of lymph distribution is repeated as lymph passes through a succession of five or more nodes before flowing into the cisterna chyli. The complexity of the lymph pathways, it is suggested, would promote the mixing of lymph from different parts of the intestine and from different nodes, thus collating, integrating, and potentiating the immunological responses of these nodes.The walls of lymphatic vessels are well endowed with smooth muscle cells and elastic fibres, suggesting that intrinsic contractility of these vessels is a major mechanism in the propulsion of lymph from the intestine of the horse.