bluuebunny/crossref_metadata_2025_split huggingface dataset:
Megakaryocytopoiesis in the spleen of growing rats
Authors: Grouls V. , Helpap B. 
Published: February 2005

AbstractAge‐dependent changes in splenic megakaryocytopoiesis of Wistar rats, 1 hour to 60 days old, were investigated using autoradiograms of semithin sections. The highest values for 3H‐thymidine labeling and mitotic indices were observed immediately after birth, whereas the maximal concentration of megakaryocytes was seen on the 14th day after birth. The transit time of megakaryocytes in newly born rats was 34.5 hours and, thus, much shorter than in adult animals.
Skeletal muscle fiber splitting with weight‐lifting exercise in rats
Authors: Ho Kwok‐Wai , Roy R. R. , Tweedle C. D. , Heusner W. W. , van Huss W. D. , Carrow R. E. 
Published: February 2005

AbstractAdult male albino rats were assigned randomly to control (CON) and weight‐lifting (WL) groups. The WL rats were subjected to a progressive weight‐lifting program against high resistance for 8 weeks. During the last 2 weeks, each WL rat lifted a load equal to 130% of its body weight. The mean weight of the adductor longus muscle was significantly increased in the WL group (p < 0.05). This increased muscle weight was shown to be due to an increase in the number of fibers per unit cross‐sectional area (p < 0.05), and the mean sizes of both fast‐twitch oxidative glycolytic and slow‐twitch oxidative fibers were significantly smaller in the WL rats than in the CON rats (p < 0.05). Light and electron microscopic examination showed that five out of eight WL rats exhibited longitudinally split muscle fibers, while only one CON rat had a few centrally placed nuclei. The splitting process appeared as either a “pinching‐off” of a small segment from the parent fiber or an invagination of the sarcolemma deep into the muscle fiber in a plane parallel to the sarcomeres. There were preliminary indications that this work‐induced fiber‐splitting process may be a physiological adaptation of muscle to the stress of exercise.
Ultrastructural localization of enkephalin‐like immunoreactivity in the rat adrenal medulla
Authors: Hervonen Antti , Pelto‐Huikko Markku , Linnoila Ilona 
Published: February 2005

AbstractThe PAP method was applied to adrenomedullary cells to demonstrate the subcellular localization of ELI. The labeled cell‐groups were identified from flat‐embedded virbratome sections by light microscopy. Electron microscopy showed that the precipitate was associated with the storage granules of the cells. The number of labeled granules varied greatly from cell to cell. In cells corresponding to those showing heavy staining by light microscopy, all the granules were stained with precipitate. It is suggested that the peptide responsible for the ELI might be released together with the catecholamines.
Gap junctions in early amphibian embryos
Authors: Hanna R. B. , Model P. G. , Spray D. C. , Bennett M. V. L. , Harris A. L. 
Published: February 2005

AbstractCell pairs from late cleavage and early blastula Ambystoma mexicanum embryos were found to be electrotonically coupled. Thin‐section electron microscopy revealed typical gap junctions between the cells. Freeze‐fracture electron microscopy showed the gap junctions to be comprised of aggregations of 8.5‐nm P‐face particles and corresponding E‐face pits. The conductance of the amphibian embryonic gap junction is known to be voltage‐dependent, but no obvious gating structure was resolved by these morphological techniques.
Cupular secretion by Xenopus laevis line organs: Autoradiographic evidence for incorporation of 3H‐glucose and 35S‐sulfate
Authors: Cornford Marcia E. , Barajas Luciano 
Published: February 2005

AbstractAutoradiographic evidence for incorporation of 3H‐glucose and 35S‐sulfate into the cupulae of Xenopus laevis (African clawed toad) lateral line organs was obtained after injection into the dorsal lymph sacs of adult animals. Time intervals of 15 minutes to 4 hours after administration of these labeled metabolic precursors were used to examine the time course of the apparent mechanism of growth of the cupulae. Our results suggest that the two layers of accessory cells (the sustentacular cells and inner layer of mantle cells), concentrically arranged around the organ's central sensory (hair) cells, elaborate distinct cupular components. Sustentacular cells, immediately adjacent to the sensory cells, appear to produce and extrude at their exposed apices a cupular “core” substance labeled by 3H‐glucose, but not by 35S‐sulfate. The layer of inner mantle cells, external to the sustentacular cells, was labeled by both precursors and is spatially situated to secrete a cupular sheath enclosing the cupular core. Ultrastructural differences between the secretory products within the two cell types were marked. Electron microscopic autoradiography of toads killed 4 hours after 3H‐glucose injection showed that silver grains were associated with accumulations of the respective secretory products in sustentacular and inner mantle cells, and label was found over the cupular trough area, where the bases of the cupulae are attached. These results suggest that the cupular core and sheath may both contain mucopolysaccharide, and the sheath, a sulfated mucopolysaccharide.
Transplantation of brain tissue in the brain of rat. I. Growth characteristics of neocortical transplants from embryos of different ages
Authors: Das Gopal D. , Hallas Brian H. , Das Kunda G. 
Published: February 2005

AbstractDifferential growth of neural transplants as related to the age of the donor embryos was investigated in this study. Neocortical tissue of constant volume, obtained from embryos of 15, 16, 17, 18, 19, 20, and 21 days' gestational age, was transplanted into the cerebellum of 10‐day‐old rats. The fully grown transplants were analyzed quantitatively and qualitatively 90 days after transplantation. The ultimate volume of the transplants and the estimated total number of neurons in them followed a gradient in relation to the age of the donor embryos. At one extreme, the neural transplants from 15‐day‐old embryos grew very large, showing a 21‐fold increase in size, and at the other extreme, those from 21‐day‐old embryos grew less than two‐fold in volume. These differences were determined by the developmental history of the transplants. Neural tissue obtained from 15‐day‐old embryos contained predominantly neuroepithelial cells which continued to proliferate even after transplantation. This resulted in the large size of these transplants. At the other extreme, neural tissue from 21‐day‐old embryos contained predominantly preformed neuroblasts, and they simply differentiated after transplantation. Due to this, the transplants were small in size. Neural tissues obtained from other embryos of different gestational ages between these two extremes contained neuroepithelial cells and preformed neuroblasts in differential ratios. The number of neuroepithelial cells in the transplants and their differential proliferative activity after transplantation, and the number of neuroblasts present, determined the differential sizes of these transplants. In histological preparations, all transplants were seen to contain normal‐looking and well‐differentiated neurons, and normal‐looking neuropil. The transplants were integrated with the host brain, in that there was neither any gap nor any scar tissue between the transplants and the host neural tissue surrounding them. Neither the transplants nor the host brains showed any pathological reaction or neoplastic growth.
The subcellular localization of immunoglobulin in mouse plasma cells, as studied with immunoferritin cytochemistry on ultrathin frozen sections
Authors: Geuze Hans J. , Slot Jan W. 
Published: February 2005

AbstractCells of mineral oil‐induced plasmacytomas (MOPC) and normal plasma cells from mouse lymph nodes were used to study the intracellular localization of IgG by means of immunoferritin cytochemistry on ultrathin frozen sections. IgG was demonstrated in the rough endoplasmic reticulum, in virus‐containing smooth ER of the tumor cells, in peripheral elements at the cis‐side of the Golgi complex, and in all Golgi cisternae. It is suggested that the peripheral elements transfer IgG molecules from the RER to the Golgi complex. Vacuoles showing a strong immunoreaction occurred at the trans‐side of the Golgi complex. These vacuoles were normal in lymph node plasma cells and were occasionally seen in the tumor plasma cells. It is proposed that these vacuoles carry IgG from the Golgi complex to the cell membrane and, hence, can be considered as secretory vacuoles.
The cytologic composition of primate laryngeal chemosensory corpuscles
Authors: Idé Chizuka , Munger Bryce L. 
Published: February 2005

AbstractThe present study defines the cellular composition of chemosensory corpuscles (taste buds) present in the mucosa overlying the arytenoid cartilages of the larynx in serial sections studied by electron microscopy. Three cell types can be defined in such chemosensory corpuscles. Basal cells are relatively undifferentiated in terms of cytologic characteristics and have been identified presumptively as the stem cells for differentiation of the other two cell types. Sustentacular or supporting cells are characterized by the presence of apical electron‐opaque granules that apparently are extruded into the lumen of the pore, and are, thus, the source of the electron‐opaque extracellular material present between the microvilli protruding from the apex of the cells into the chemosensory corpuscle pore. The chemosensory cells are characterized by the presence of synaptic specializations with appended nerve fibers at the base of the cell, the presence of specific cytoplasmic secretory granules, as well as numerous clusters of typical synaptic vesicles, and apical microvilli that extend into the pore of the corpuscle. Other cell profiles encountered in chemosensory corpuscles are cells in various stages of degeneration or transition, to one of the other cell types, from undifferentiated basal cells. Two types of synaptic specializations have been identified as being associated with chemosensory cells. The first is characterized by an increased electron‐opacity of the respective plasma membranes of nerve fiber and chemosensory cell. In this situation numerous synaptic vesicles usually are present in the cytoplasm of the chemosensory cell subjacent to the membrane densities. A second type of synaptic association is characterized by the presence of subsurface cisterns of agranular endoplasmic reticulum in the cytoplasm of the chemosensory cell, and numerous synaptic vesicles often are present in the axoplasm of the subjacent neurite, suggesting a reciprocal synapse. These findings are interpreted to indicate that only one cell type is specialized for transducing chemical signals into neural activity and that this cell is modulated by activity of the nervous system.
Microvasculature of the canine heart demonstrated by scanning electron microscopy
Authors: Anderson Bettina G. , Anderson Wesley D. 
Published: February 2005

AbstractIn previous studies, a marked diminution in left coronary flow during systole has been demonstrated. This phenomenon has been said to result from capillary compression by the contraction of myocardium and perhaps also from active changes in the state of the smooth muscle in the wall of the coronary vessels. In order to determine the morphological factors involved in this occurrence, and to gain a three‐dimensional concept of the myocardial microvasculature, casts were prepared by perfusion of the coronary arteries with methyl methacrylate. Because of the conditions of the perfusion, these casts were considered to demonstrate a state of muscular contraction. Following maceration, portions of the casts were prepared for scanning electron microscopy (SEM).Arterioles of larger diameter were characterized by the helical configuration of the vascular replicas. Smaller vessels were categorized according to their directional pattern and their diameter. The arterioles gave rise to numerous large‐diameter capillaries and also to short vessels that were guarded by sphincters. True capillaries, in some cases guarded by precapillary sphincters, were packed in densely stacked parallel sheets with numerous short anastomotic connections between them. Postcapillary venules were found to enter at regular intervals into larger venules arranged perpendicular to the capillary sheets.Most of these characteristics were found to be consistent throughout the microvasculature. These structural features were considered to be factors in the active regulation of blood flow through the myocardial microvasculature.
Immunocytochemical localization of nerve growth factor, epidermal growth factor, renin and protease A in the submandibular glands of Tfm/Y mice
Authors: Gresik E. W. , Chung K. W. , Barka T. , Schenkein I. 
Published: February 2005

AbstractThe submandibular glands of mice with testicular feminization (Tfm/Y) and their normal adult male littermates (Ta/Y) were studied by immunocytochemical techniques for the demonstration of epidermal growth factor (EGF), nerve growth factor (NGF), renin and protease A. In the glands of both the affected and normal males, these polypeptides were restricted to cells of the granular convoluted tubules (GCT), with the exception of protease A, which was also found in small amounts in striated duct cells. Compared to those of Ta/Y males, GCTs were narrower in the glands of Tfm/Y mice and contained a markedly reduced number of cells immunoreactive for EGF, NGF and renin. However, the number of GCT cells that stained for protease A in the glands of Tfm/Y males was not as drastically decreased.
Formation of gap and tight junctions between reaggregated blastomeres of the killifish, Fundulus
Authors: Ne'Eman Z. , Spira M. E. , Bennett M. V. L. 
Published: February 2005

AbstractBlastomeres from eggs of the killifish, Fundulus, were mechanically dissociated and reaggregated by pelleting in a simple saline solution. Formation of gap and tight junctions was followed by electron microscopy of freeze‐ fracture replicas. Five to eight min after pelleting, neither new nor old junctions were observed. After 10–15 min, small gap junctions were found, but these were not associated with distinct formation plaques. Larger gap junctions were observed after 45 min, and the images were consistent with growth by accretion of intramembrane particles. In aggregates, after 20 min or more, tight junctions were much more commonly found than in intact blastulae, and it seemed likely that they were being formed by cells that were not doing so in the intact embryo. Initial stages consisted of short strands that appeared to grow in length. Also, more elaborate junctions were seen than occur in situ. Particle‐free membrane often occurred near incomplete junctions, and large junctions like those in situ separated particle‐rich from particle‐free membrane. In this system, the formation of both gap and tight junctions occurs with shorter latency, and is more precisely timed, than heretofore described.
Gap junctions between sensory and supporting cells of the utricular and saccular maculae in Anolis carolinensis examined by transmission electron microscopy
Authors: Zahm D. S. 
Published: February 2005

AbstractGap junctions, related to projections of sensory cells into supporting cells, occur from supranuclear to basal levels on hair cells, in both saccular and utricular maculae of the lizard, Anolis carolinensis. The larger numbers of junctional projections observed at some levels may indicate a zonular distribution within the neuroepithelia, but only on supracalyceal parts of hair cells in the utricular striola was a series of gap junctions found to be closely associated with the reticular lamina. The dimensions of the junctions, as characterized by the distance between opposite extremities of the arciform membrane appositions, averaged 0.14, 0.19, and 0.28 μm, respectively, on non‐calyceal utricular and saccular hair cells, and calyceal cells of the utricular striola. A notable number of the junctional profiles were adjacent or contiguous to open, coated, putatively endocytotic vesicles. These findings are discussed in respect to phylogenetic, developmental, and functional considerations.
A scanning electron microscopic study of the ferret atrioventricular node
Authors: Marino Thomas A. 
Published: February 2005

AbstractThe atrioventricular (AV) node and surrounding transitional zone in the ferret heart were examined with scanning electron microscopy. This permitted the direct visualization of the three‐dimensional cell shape, as well as intercellular relationships. Transitional cells were roughly cylindrical with extensively branching end processes. These cells were apposed to many adjacent transitional cells. The superficial AV nodal cells were smaller than transitional cells and were fusiform in shape. Most of the cell contacts between superficial AV nodal cells were between overlapping end processes, and there was very little branching of these cells. The deep AV nodal cells were similar to the superficial AV nodal cells, but were slightly larger and also had more cell contacts with adjacent cells. The possible significance of cell size and shape and intercellular relationships as they relate to atrioventricular impulse propagation and AV nodal delay are discussed.
Ultrastructural changes in type I and type II alveolar epithelial cells in isolated perfused dog lungs after production of moderate and severe hydrostatic edema
Authors: DeFouw David O. 
Published: February 2005

AbstractVolume densities of type‐I and type‐II alveloar cell cytoplasmic organelles were estimated by established stereologic procedures. The measurements were obtained from isolated‐perfused dog lungs after the onset of acute hydrostatic edema. The isolated lungs provided three successive lobar preparations: control, moderately edematous, and severely edematous. The type‐II cell lamellar body volume densities were decreased in both stages of edema. Volume density of the granular endoplasmic reticulum (including polyribosome clusters) was increased after progression to severely edematous conditions. Concomitant increases in vesicular volume densities were recorded in type‐I cells after both moderate and severe edema. In addition, the relative percentages of vesicles directly attached to the luminal and abluminal plasma membranes were increased in the edematous lungs. These marked ultrastructural changes in the alveolar epithelium are consistent with the interpretation that both the release of lamellar bodies from type‐II cells and the number of type‐I cell pinocytotic vesicles are increased in isolated dog lungs after production of edema.
Acid‐proteinase activity of rat cartilage dependent on growth hormone
Authors: Owers Noel O. 
Published: February 2005

AbstractCartilage slices from normal rats, incubated at pH 4 for 3 to 7 hours, on a gelatin‐membrane substrate, digested the membrane, whereas cartilage from rats hypophysectomized for 21 days or more did not. Injection of 15 or 45 μg of bovine growth hormone into hypophysectomized rats restored the lytic activity of the cartilage. It is concluded that an acid proteinase is present in cartilage of normal rats, that is lost after hypophysectomy, and that the enzyme is restored by injection of growth hormone.
An immunocytochemist's view of gonadotropin storage in the adult male rat: Cytochemical and morphological heterogeneity in serially sectioned gonadotropes
Authors: Childs (Moriarity) Gwen V. , Ellison Dayle G. , Garner Laura L. 
Published: February 2005

AbstractThis study was designed to elucidate hormone storage patterns in gonadotropes with the use of ultrastructural immunocytochemistry on serial ultrathin sections. Sets of six serial sections were stained for beta chains of LH, FSH, or the C‐Terminal sequence of ACTH, and 430 cells cut in triple or double serial section were collected from a group of seven normal adult male rats. Approximately 50‐88% of the cells contained both LH and FSH, and most of these were Type I cells which are distinguished by their round shape and heterogeneous populations of secretion granules. Cells containing only FSH or LH constituted, on average, 19% of the population. These were a mixed group, morphologically, and included Type II cells distinguished by their angular shape and population of secretion granules, 250 nm in average diameter. Also among the FSH cells (and a few LH cells in two of the rats) were Type III cells, which resemble the corticotrope. On average, 10% of the serially sectioned cells contained only ACTH. Our findings show the presence of subpopulations of gonadotropes containing only one of the hormones, in numbers large enough to support the hypothesis that they may be partly responsible for the nonparallel release of gonadotropins. Also, the FSH‐LH cells seemed to vary in their staining intensity for the two hormones, suggesting that the gondaotropes are a fluid, heterogeneous population of cells capable of storing both or only one of the hormones.
Immunocytological study of the differentiation of chick and quail adenohypophysis epithelial rudiments, grafted or cultivated in vitro: Evidence for polypeptidic hormones
Authors: Ferrand Raymond , Fremont Patrick H. , Dubois Maurice P. 
Published: February 2005

AbstractEpithelial rudiments of adenohypohysis were removed from chick and quail embryos between days 3 and 5 of development. Chick rudiments were grafted for 11–13 days onto the chorioallantoic membrane of decapitated chick embryo hosts. Quail rudiments were cultivated in vitro for 6 days. Both grafted and cultivated Rathke's pouches differentiated into adenohypophyseal tissue. The adenohypophyseal tissue cultured on chorio‐allantoic membrane exhibited cells reacting with the following immune sera: anti‐β‐(1–24)ACTH, anti‐α‐(17–39)‐ACTH, anti‐α‐endorphin, anti‐β‐endorphin and anti‐β‐LPH, which also gave a positive reaction when applied to adenohypophysis of corresponding age which had differentiated in situ. In situ, corticotrophs were located exclusively in the cephalic lobe of adenohypophysis. Therefore, the differentiation of corticotrophs in the whole graft, i.e., from both cephalic and caudal lobes of Rathke's pouch, showed that the cells of the caudal lobe, or at least some of them, were uncommitted when the rudiment was removed. In vitro, tissue derived from Rathke's pouch contained cells reacting with antibodies to β‐(1–24)‐ACTH, α‐(17–39)‐ACTH, and β‐LPH, as did adenohypophysis from quail embryos of corresponding age (9–10 days), differentiated in situ. The differentiation of quail Rathke's pouch in vitro corroborates that differentiation can occur without influence from hypothalamus and, moreover, shows that at least some kinds of cells can differentiate without influence exerted by any other encephalic factors, and in the absence of mesenchyme. The question arises whether fibroblastic cells derived from Rathke's pouch cells act as feeder‐cells and/or secrete some factors promoting differentiation.