bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fine structure of monkey sertoli cells in the transitional zone at the junction of the seminiferous tubules with the tubuli recti
Authors: Dym Martin 
Published: February 2005

AbstractThe monkey testis contains an axial rete in a highly vascular central core of loose connective tissue. Seminiferous tubules join the rete along its entire length. The short terminal segments of the tubules are lined mainly by Sertoli cells. There is then a transition from Sertoli cell epithelium to the simple cuboidal epithelium of tubuli recti, which connect the seminiferous tubules to the rete testis.Electron microscopic observations of the Sertoli cell in the terminal regions of the seminiferous tubules reveal a highly lobulated nucleus, a unique nucleolus and a columnar cell body with an irregular free surface bearing processes of varied form projecting into the tubule lumen. The cytoplasm is characterized by a well developed rough endoplasmic reticulum, large numbers of lipid droplets, and an extraordinary abundance of 70 Å filaments. Occasionally these latter are so densely packed that other organelles are excluded from large areas of the cytoplasm. Profiles of smooth endoplasmic reticulum are few in marked contrast to the usual condition of Sertoli cells elsewhere in the seminiferous tubules.Many of the Sertoli cells in the terminal regions of the seminiferous tubules contain spermatozoa in various stages of degradation. Small lymphocytes, never observed in normal seminiferous tubules, are distributed in small numbers among the Sertoli cells of the transitional zone. No desmosomes or other junctional specializations are observed at the interface of lymphocytes with the surrounding Sertoli cells. The cytology of the terminal region of the seminiferous tubules is discussed in relationship to exit of sperm from the tubules, the blood‐testis barrier, and the pathogenesis of immune orchitis.
“Caveolated cells” characterized by deep surface invaginations and abundant filaments in mouse gastro‐intestinal epithelia
Authors: Nabeyama A. , Leblond C. P. 
Published: February 2005

AbstractLight and electron microscope examination of gastro‐intestinal epithelia in the adult mouse revealed the widespread presence of a cell type characterized by deep surface invaginations or “caveolae” and, accordingly, called “caveolated cell.”The caveolated cells are scattered within the epithelia of stomach, small and large intestine; they have a narrow apex bordering the lumen and a wide base in contact with the basement membrane. In the light microscope, they display microvilli longer than in nearby cells; the cytoplasm is usually pale and contains an apical group of parallel fibrils, next to which are minute light spaces which may correspond to the caveolae. In the electron microscope, each fibril is found to be composed of a bundle of straight filaments, extending from the core of a microvillus down into the deeper portion of the supranuclear region; microtubules are often associated with these filaments. Filaments of a different type are arranged in bundles which go from desmosome to desmosome around the apical region of the cell. The caveolae are long and tortuous channels opening at the cell surface between the microvilli and extending deep into the cytoplasm. From the walls of caveolae, polyp‐like structures project into the lumen. The heads of the polyps are believed to be released into this lumen where they appear as small spheres. These in turn may come out of the caveolae to appear between and next to the microvilli.Caveolated cells are not numerous, e.g., they make up less than 1% of the epithelial cells in the crypts of descending colon. They may be found in the intestinal crypts among poorly differentiated cells, and at the surface of stomach and intestine among fully differentiated cells. They appear to undergo renewal, but since they have not been seen in mitosis, they probably arise from the differentiation of some other epithelial cells.
Changes in the mucosa of the small intestine following methotrexate administration or abdominal X‐irradiation
Authors: Altmann G. G. 
Published: February 2005

AbstractAdult male rats received 5 mg methotrexate daily and were sacrificed 1, 1.5, 2, 2.5 and 3 days after the beginning of the treatment. Other groups received 9,000 rads of abdominal x‐radiation and were sacrificed 1, 2 and 3 days later. Histological samples were taken from five regions of the small intestine and processed for light microscopic examination. Average area occupied by the crypts and the villi respectively, was measured per unit length of histological section. A few animals received 3H‐thymidine an hour before the methotrexate treatment or irradiation; the histological samples were processed for radioautography.Significant mitotic activity was absent throughout the experiments. During the first 1.5 days, mainly the crypts diminished. Radioautography revealed that migration of crypt cells to the villi continued during this time. During the second and third days, the villi also showed marked diminution, and cell migration became irregular. In general, the histometric data were similar after methotrexate and irradiation. Epithelial denudation started in terminal ileum on the third day after methotrexate. The epithelium was much reduced but not yet denuding at this time in the irradiated animals.Methotrexate inhibition of DNA and RNA synthesis was assumed to be associated, respectively, with mitotic inhibition and with a decline of protein synthesis which manifested itself in villus diminution. Survival of epithelial cells varied presumably according to the amount of RNA pool and was longest in cells being in the S‐phase at the onset of the treatment. The similarity of the data after irradiation implied a similar sequence of events.
Hepatic glycogen patterns in fasted and fed rats
Authors: Babcock Muriel B. , Cardell Robert R. 
Published: February 2005

AbstractHepatic glycogen patterns are described for rats adapted to a precisely controlled feeding schedule and ad libitum fed rats. Liver samples were processed for biochemical and histochemical glycogen analysis at precise intervals following a 22 hour fast and a 2 hour meal. Histochemical determination of glycogen (PAS) after freeze substitution showed lobular patterns of hepatic glycogen which correlate with chemically determined glycogen levels and nutritional states of the rats. After 22 hour fasting, hepatocytes from rats with low glycogen levels (< 0.09%) exhibited no significant staining. In control fed rats, feeding caused glycogen deposition throughout the lobule but in greatest concentration centrilobularly throughout the early phases of glycogen accumulation. As glycogen deposition continued, periportal lobular patterns were observed in rats with high glycogen levels (> 5%). Glycogen depletion reduced glycogen staining in cells throughout the lobule, but centrilobular patterns prevailed until late in depletion when periportal patterns appeared. Ad libitum‐fed rats showed similar glycogen patterns except maximum deposition was characterized by centrilobular or even lobular distribution of glycogen, and periportal patterns of glycogen were seen only rarely in extreme fasted rats. Differences in lobular patterns between ad libitum and control fed rats is apparently related to lower maximum hepatic glycogen levels reached by ad libitum‐fed animals.
Studies on the response of the adult newt kidney to partial nephrectomy
Authors: Scadding Steven R. , Liversage Richard A. 
Published: February 2005

AbstractThe response of the kidneys of 237 adult newts [Notophthalmus (Diemictylus) viridescens] to partial nephrectomy (15 to 30% of right kidney removed) and sub‐total nephrectomy (70 to 90%) was studied histologically and autoradiographically to determine their regenerative potential. The response involved both hypertrophy and hyperplasia as indicated by increases in 3H‐thymidine labelled nuclei and also 3H‐leucine incorporation by the remaining cells of the kidney. Leucine incorporation increased within 24 hours and continued to increase until 5 days after partial nephrectomy (17% increase over control level) or 15 days after sub‐total nephrectomy (36% increase). The number of thymidine labelled nuclei, however, did not increase for the first 5 days and then continued to increase up to 10 days after partial nephrectomy (to 3X control level) and 20 days after sub‐total nephrectomy (to 5X control level).An accumulation of cells appeared on the cut surface of the kidney by 15 to 20 days after nephrectomy. It consisted of modified epithelial cells from the tubules and was characterized by marked basophilia. The number of 3H‐thymidine labelled nuclei in the accumulation increased about 10 to 20 times over control levels at its peak on days 12 to 15; 3H‐leucine incorporation doubled at its peak on days 10 to 15. Nevertheless, after day 20 the cell accumulation decreased in size due to cell resorption or sloughing or both; it had disappeared by day 50 with no new tissue resulting. The newt kidney does not appear to exhibit any regenerative potential and, therefore, it is similar to mammalian kidneys in this respect.
The fetal membranes and unusual giant cell placenta of the jerboa (Jaculus) and jumping mouse (Zapus)
Authors: King Barry F. , Mossman Harland W. 
Published: February 2005

AbstractThe development of the fetal membranes of the North African jerboa (Jaculus) and the North American jumping mouse (Zapus) were examined by light microscopy, and the interhemal membrane of Zapus was studied by electron microscopy. Early stages of Jaculus show implantation to be antimesometrial with the embryonic disc oriented mesometrially. Amniogenesis is by folding and there is a distinct epamnionic cavity. Yolk sac inversion is complete, but the disappearance of the parietal segment occurs relatively late, during the early fetal period. Those early stages of Zapus which were available indicated a close similarity to Jaculus. Both Jaculus and Zapus are unusual in the manner of development and composition of the chorio‐allantoic placenta. Development of cytotrophoblast and syncytiotrophoblast is arrested early and these layers eventually disappear. Trophoblastic giant cells migrate into the allantoic mesenchyme to form the maternal blood channels of the labyrinth. In Jaculus, a complex interdigitation exists between yolk sac villi and arterial channels bringing maternal blood to the labyrinth. This relationship is much less intimate and extensive in Zapus. Electron microscopic examination of the interhemal membrane of Zapus shows it to be hemomonochorial, its only trophoblastic element being the giant cell cytoplasm. Thus, the Zapus placenta is to date one of very few hemochorial placentas known to lack trophoblastic syncytium in its interhemal membrane. Comparison of the total development and structure of the fetal membranes in these two genera with that of other rodents indicates that the membranes of the Dipodoidea, like the Geomyoidea, are intermediate in type between those of the Sciuromorpha and Myomorpha.
Autoradiographic localization of 3H‐testosterone or its metabolites in the neonatal rat brain
Authors: Sheridan Peter J. , Sar Madhabananda , Stumpf Walter E. 
Published: February 2005

AbstractThe distribution of neurons which concentrate testosterone or its metabolites in the brain of 2‐day old female rats was determined using autoradiography. A specific topographic pattern of neurons which concentrate testosterone or its metabolites was obtained similar, but not identical, to the one found in adult male rats. The demonstrated sites of nuclear uptake and retention of testosterone or its metabolites by specific neurons in the neonatal brain probably provide the anatomical substrate for sexual differentiation of the brain.
A cytochemical and radioautographic analysis of erythropoiesis at the ultrastructural level
Authors: Rosse Cornelius , Trotter John A. 
Published: February 2005

AbstractThe morphogenetic events of erythroid differentiation in guinea pig bone marrow were studied by electron microscopy. The diaminobenzidine (DAB) reaction and radioautographic detection of Fe55 incorporation permitted a more objective identification of erythroid cells than was possible in previous studies. With the combined use of these two methods morphological events of cell maturation could be correlated reliably with cytoplasmic hemoglobin content, thus providing a basis for the description of various maturation stages.The oxidation of DAB by hemoglobin coupled with OsO4 treatment results in a generalized increase in cytoplasmic electron opacity proportional to the amount of hemoglobin present. Measurements of cytoplasmic density were carried out on electron microscopic negatives of DAB‐reacted specimens that were not stained otherwise. Only those cells were regarded as erythroblasts in which the cytoplasm was at least twice as dense as in recognizable, differentiated, non‐erythroid cells, using reticular cell cytoplasm in each specimen as the base line for the comparisons.In bone marrow cells, iron incorporation occurred overwhelmingly for hemoglobin synthesis. In normal marrow, blast cells which incorporated iron but did not contain hemoglobin in detectable amounts were defined as Stage I erythroid cells. They were morphologically of the same type as erythroblasts with the minimum amount of detectable hemoglobin (Stage II). Cells in maturation stages of progressively increasing hemoglobin content were assigned to Stages III to V. Stage III erythroblasts correspond morphologically to proerythroblasts of light microscopic preparations. The DAB reaction in them was obvious without densitometric measurements but remained mottled.The morphological characteristics of each of the maturation stages are described with particular emphasis on the earliest erythroid cells, since the methods employed permit their identification with greater degrees of discrimination and objectivity than is possible with the light microscope or with conventional methods of electron microscopy.The DAB reaction was positive in the heterochromatin in Stages III and IV but it was negative in the pyknotic chromatin of erythroblasts in Stage V of maturation. The predominantly extended chromatin and also the large and complex nucleoli of earlier cells began to condense during Stage IV. Silver grains due to Fe55 disintegration were observed over the nuclei of erythroblasts in all maturational stages.The perinuclear cisterna was DAB‐negative and it became wider as maturation progressed. It was bridged in places by DAB‐negative material connecting the cytoplasm to euchromatic areas of the nucleus. DAB‐positive substance was not seen in nuclear pores at any stage of maturation. At the time of extrusion, nuclei did not contain DAB‐positive material but were occasionally labeled with Fe55.
Constant occurrence of adrenocortical tissue in the juvenile rabbit ovary
Authors: Mori Hiroshi , Matsumoto Keishi 
Published: February 2005

AbstractAdrenocortex‐like cells were consistently found in the mesovarium or in the hilus of the ovary of rabbits less than three months old. The adrenocortex‐like cells occurred usually in the form of nodules among or near the mesonephric tubules. But they sometimes appeared within the rete ovarii either in direct contact with the epithelial cells or scattered in the stroma. Similar cells were newly formed in the ovarian medulla of one‐month‐old rabbits following injection of ACTH (adrenocorticotropic hormone).Electron micrographs showed that the adrenocortex‐like cells characteristically had a well developed agranular endoplasmic reticulum and mitochondria containing tubular cristae which were arranged in villiform fashion. In addition, most endothelial cells of the capillaries among the adrenocortex‐like cells had fenestrations. The enzyme activity of 3β‐hydroxysteroid dehydrogenase was histochemically demonstrated only in the identical cells of one‐month‐old rabbits. It was concluded, therefore, that the adrenocortex‐like cells in the rabbit ovary were actually adrenocortical cells.This morphological conclusion was confirmed by the biochemical demonstration of 11β‐hydroxylase, an enzyme specifically found in the adrenal cortex. The ovarian tissue, including the mesovarium from one‐month‐old rabbits, was capable of converting progesterone to corticosterone.
Light and electron microscopic studies of retzius lines in human cervical enamel
Authors: Weber Dennis F. , Eisenmann Dale R. , Glick Paul L. 
Published: February 2005

AbstractUnaltered mature enamel and partially demineralized mature enamel from the cervical third of human permanent teeth were examined by means of transmission electron microscopy, microradiography, phase contrast and Nomarski differential interference microscopy. The Retzius lines in the outer third of the cervical enamel had a staircase configuration. The steps in the stair‐case pattern formed the bases of triangular regions which were radiolucent and ultrastructurally contained fewer crystallites than the adjacent enamel. In the outer prismless layer, the Retzius lines had a curvilinear configuration and were also crystallite deficient. The structure of the Retzius lines in the inner portion of the cervical enamel was not nearly as well defined.
Cell types in cutaneous type I mechanoreceptors (Haarscheiben) and their alterations with injury
Authors: English Kathleen B. 
Published: February 2005

AbstractType I mechanoreceptors (also called Haarscheiben or “domes”) are small elevations on the cat's skin, each being supplied by a myelinated sensory fiber. The fiber terminates in apposition to specialized receptor cells (Merkel cells) lying at the base of the epithelium investing the structure. When a group of domes was injured some of the neighboring domes became structurally altered as determined by light and electron microscopy. The changes observed resembled those which accompany denervation and involved the loss of Merkel cells and their apposed sensory nerve terminals from the dome. Since this trauma was produced indirectly it has been called secondary injury. Cells showing some of the morphological features of both keratin‐producing epithelial cells and Merkel cells were observed in secondarily injured domes and in non‐injured domes. The presence of such transitional cells suggests that Merkel cells may be derived from keratinocytes.
The permeability to carbon of the sinusoidal lining cells of the embryonic rat liver and rat bone marrow
Authors: Bankston Patrick W. , De Bruyn Peter P. H. 
Published: February 2005

AbstractThis study is concerned with the passage of carbon particles through the sinusoidal lining cells of bone marrow and embryonic liver of the rat. A carbon suspension (Pelikan C11/1431A, Günther Wagner, Hanover) diluted 1:1 with double strength Tyrode solution, was administered through the aorta for the bone marrow studies and through the umbilical vein for observations on the embryonic liver. The carbon particles have a diameter ranging from 220 to 380 Å with a mean diameter of 280 Å. Within three minutes after the injection, the particulate was present in the extravascular spaces. Neither the sinusoidal walls of the bone marrow nor of the embryonic rat liver prior to 16 days gestation have preformed apertures. In both cases, the carbon particles enter the extravascular space through fenestrae with diaphragms. No carbon particles occur in the junctional spaces between the lining cells. The temporary pores caused by diapedetic blood cells maintain a tight seal and no particulate was observed leaving the vascular space at these sites. At 17 days of gestation, open gaps develop in the endothelial lining of the embryonic rat liver and particulate material leaves the vascular lumen through these openings. The presence of bristle‐coated vesicles containing particulate material at the abluminal side of the lining cells is interpreted as a retrograde uptake by these phagocytic cells rather than as evidence for vesicular transmural transport.
The mode of origin of pulmonary acini and respiratory bronchioles in the fetal lung
Authors: Boyden Edward A. 
Published: February 2005

AbstractBetween the 50th day of embryonic lifeStage 20 (O'Rahilly and Boyden, '73; Wells and Boyden, '54).
and the 30th week of gestation no reconstructions of the developing parenchyma of the human lung seem to have been attempted. To bridge this long gap, only two techniques have been utilized hitherto: counting the generations of branches in the growing segments of the lung and analyzing the changing cytology with the aid of the electron microscope. At least two important objectives remain: a knowledge of when the respiratory units known as pulmonary acini appear and the order in which capillary invasion of its component parts takes place.At the 16th week of gestation, peripheral units have not attained their full complement of branches and their boundaries are not delimited. At 17 weeks, acini of varying sizes can be recognized as discrete terminal units at the periphery of the segmental trees, having attained their full, though underdeveloped, complement of fetal branches, as gauged by later counts of generations made at 30 weeks of age (Boyden, '69). The 17th is also the week in which capillaries first invade the peripheral branches of the acinus. Although significantly later stages have not yet been obtained, the evidence available (including that from unpublished work on monkey fetuses) strongly suggests that canalization (before birth), like alveolization (after birth)Boyden and Tompsett, '65; Boyden, '67.
proceeds mainly in a centripetal direction.
Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine I. Columnar cell
Authors: Cheng Hazel , Leblond C. P. 
Published: February 2005

AbstractThe columnar cells, i.e., the cells which contain neither mucous globules, nor entero‐endocrine granules, nor Paneth type secretion, were investigated independently of other cells in duodenum, jejunum and ileum using light and electron microscopy as well as radioautography in mice sacrificed at various times after single injection or continuous infusion of 3H‐thymidine.The columnar cells exhibit local differences allowing their classification into four sub‐groups: (a) The crypt‐base columnar cells are immature proliferative cells occupying the nine lowest cell positions of the crypt on the average. (b) The mid‐crypt columnar cells occupy the next positions up to 19 in ileum and 27 elsewhere; they proliferate and show features gradually changing from undifferentiated ones near the base to partially differentiated ones higher up. (c) The crypt‐top columnar cells occupy the rest of the crypt; they do not divide but they continue to differentiate. (d) Finally, the villus columnar cells are fully differentiated absorptive cells.Cryp‐base and mid‐crypt columnar cells take up 3H‐thymidine label prior to division. With time after a 3H‐thymidine injection, the intensity of their labeling decreases, while heavily labeled columnar cells appear in crypt‐top by six hours and on the villus by 12 and more hours. Hence, columnar cells migrate. The migration is associated with gradual differentiation from the immature crypt‐base columnar cells to the mature villus columnar cells. The latter eventually reach the villus tips where they drop into the lumen.The columnar cells constitute a large majority of the epithelial cells (95, 94 and 89% in duodenum, jejunum and ileum, respectively). Hence, they are likely to play a key role in the renewal of the epithelium in the three regions of the small intestine. The turnover time of columnar cells estimated from results of continuous 3H‐thymidine infusion is 3.3 days in duodenum and 3.4 days in jejunum.Evidence from turnover time data indicates that the mitoses of columnar cells produce more cells than required for their own renewal. Presumably some of the mitoses give rise to cells of a type other than columnar.