bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology, proliferation, and differentiation of undifferentiated spermatogonia in the chinese hamster and the ram
Authors: Lok D. , Weenk D. , de Rooij D. G. 
Published: February 2005

AbstractThe population of undifferentiated spermatogonia was studied in whole mounted seminiferous tubules of the Chinese hamster and the ram. The morphology of the differentiating spermatogonia in the ram is also described.The nuclear morphology of the undifferentiated spermatogonia was found to vary considerably. 3H‐thymidine labeling studies in the Chinese hamster revealed that this variability is associated with the phases of the cell cycle. In both animals the undifferentiated spermatogonia were found to lie isolated (As), paired (Apr), or in groups of four, eight, or sixteen cells (Aal). We described how the varying morphology can be used to identify the composing clones of a cluster of undifferentiated spermatogonia.Cell counts performed throughout the whole cycle of the seminiferous epithelium revealed a very similar pattern of proliferation in the Chinese hamster and the ram. The number of As + Apr spermatogonia remained constant throughout the epithelial cycle. However, the occurrence of labeled and mitotic cells showed that As, Apr as well as Aal spermatogonia do proliferate. In both animals the mitotic activity of the undifferentiated spermatogonia is very low during the lifespan of A2 spermatogonia but increases considerably among A3, staying high among Intermediate spermatogonia. Thereafter, mitotic activity subsides to a lower level until the cycle repeats itself. Clones of 16 Aal in the Chinese hamster only exceptionally divide further.The results in the ram are incompatible with a scheme of stem cell renewal in which the A1 spermatogonia derive from A2 spermatogonia (Hochereau‐de Reviers et al., 1976). It is proposed that in the ram, like in rodents, the As spermatogonia are the spermatogonial stem cells and that the A1 spermatogonia derive quantitatively from the undifferentiated spermatogonia at each epithelial cycle.It could be calculated from the number of newly formed clones that both in the Chinese hamster and the ram, on the average, each As spermatogonium will have to divide several times during one epithelial cycle.Unlike in rodents, in the ram differentiation into A1 spermatogonia brings about a distinct morphologic change enabling us to observe that some Apr and rarely As spermatogonia transform into A1 spermatogonia. Thus, all undifferentiated spermatogonia are able to differentiate into A1 but the chance for this to occur increases strongly with the clonal size.
Continuity of intracellular channels with extracellular space in adipose tissue and liver: Demonstrated with tannic acid and lanthanum
Authors: Joan Blanchette‐Mackie E. , Scow Robert O. 
Published: February 2005

AbstractTannic acid was used to demonstrate continuity of intracellular channels with extracellular space in white adipose tissue of adult rats, brown adipose tissue of suckling rats, and liver of diabetic rats. Electron‐opaque material resulting from treatment of glutaraldehyde‐fixed tissue with tannic acid was found in extracellular space, invaginations of cell surfaces, vesicles, and intracellular channels. Electron‐opaque material was present in channels that surrounded lipid droplets in both white and brown adipocytes and in hepatocytes. The small distance between the lumen of marked channels and lipid droplets in adipocytes indicates that a monolayered structure, perhaps a leaflet of membrane lining the channel, separates the lipid droplet from the lumen of the channel, suggesting that the lipid droplet may be located between leaflets of the membrane lining the channel. Similar findings were obtained in brown adipose tissue using lanthanum instead of tannic acid to mark intracellular channels continuous with extracellular space. Since endoplasmic reticulum is the primary site of triacylglycerol synthesis in adipocytes, marked channels near lipid droplets may be elements of endoplasmic reticulum. Some of the channels marked with tannic acid in hepatocytes contained lipoprotein particles, whereas others were located, in relation to mitochondria and lipid droplets, in the same sites as endoplasmic reticulum in untreated tissue. This indicates that some of the channels marked with tannic acid in hepatocytes are endoplasmic reticulum. Presence of electron‐opaque material in intracellular channels and vesicles, but not in cytoplasm, of treated tissue indicates the channels and vesicles were open to extracellular space during treatment with tannic acid or lanthanum and, furthermore, that their membranes were continuous with plasma membrane.
Proliferative activity in the rat epididymis during postnatal development
Authors: Sun Eric L. , Flickinger Charles J. 
Published: February 2005

AbstractThe proliferative activity of the rat epididymis during postnatal development was investigated with the use of autoradiography. Animals at 14, 21, 28, 35, and 56 days of age were sacrificed 2 hours following the administration of 3H‐thymidine. Cell types that showed a significant labeling index were columnar cells in 14‐ and 21‐day‐old animals; principal and basal cells in 28,35 and 56 day old rats. During this period of development, the pattern of cellular activity in the initial segment differed from the middle and terminal segments in having a peak of activity on day 28. The middle and terminal segments had similar proliferative patterns.In two additional experiments, 10‐ and 21‐day‐old rats were given 3H‐thymidine and killed 1 week later on day 16 and 28. Labeled narrow cells were present in day 16 animals, whereas labeled narrow, principal, and basal cells were found in day 28 rats. It was concluded that columnar cells are the precursor to narrow, principal and basal cells.
Development of neuroepithelial bodies in pre‐ and postnatal mouse lungs: Scanning electron microscopic study
Authors: Hung Kuen‐Shan 
Published: February 2005

AbstractThe development of pulmonary neuroepithelial bodies (NEBs) in pre‐ and postnatal mice were studied with scanning electron microscope. In the fetuses, at 17 days' gestation, the NEBs were recognized as slight epithelial elevations covered by developing Clara cells. At 18 days, the small apical surfaces of the specialized cells began to be exposed to the bronchiolar lumen. At 19 days (full term), numerous microvilli‐covered surfaces of the specialized cells were located between the dome‐shaped Clara cells. At this stage, the boundary of the NEBs was well outlined by the developing ciliated cells. In the postnatal animals, the surface structure of the specialized cells remained the same as that of the 19‐day fetuses, but the modified Clara cells gradually became wide and flat. In older mice, some NEBs formed obvious spherical mounds projecting into the bronchiolar lumen. The rapid differentiation of the microvillar projections on the surfaces of the specialized cells shortly before birth should provide the animals ample surface area to make contact with the airway contents.
Osmium vapor fixation of pulmonary surfactant
Authors: Callas Gerald 
Published: February 2005

AbstractElectron microscopic techniques presently employed to preserve the alveolar lining layer are inadequate, and published reports have failed to demonstrate surfactant as a continuous layer over the alveolar surface. Osmium vapor insufflation into the airway combined with vascular perfusion preserves the alveolar lining layer (surfactant). In all the alveoli studied, the combination of airway and vascular fixation of the surfactant layer offers a visualization of surfactant as a continuous layer over the alveolar surface.
A new plastic for morphometric investigation of blood vessels, especially in large organs such as the human liver
Authors: Hanstede Johan G. , Gerrits Peter O. 
Published: February 2005

AbstractIn this paper a technique is described, using Araldite CY 223 and hardener HY 2967 as injection material, for preparing corrosion casts or histological sections. The plastic has a viscosity (at 39–40°C) similar to that of blood, a gelling time of approximately 17min (at 40°C), and an exothermic transition energy of ΔH = 80.28 ± 3.20 cal/gm. The influence of the plastic on the tissue is discussed. The histological sectioning of fixed tissue containing Araldite‐filled blood vessels after embedding in 2‐hydroxyethyl‐methacrylate (GMA) is described. When using GMA in a modification of the mixtures of Ruddell (1967) and Sims (1974), methylbenzoate is recommended as an intermedium in order to obtain a more uniform infiltration and reproducible section thickness. At the same time methylbenzoate is recommended as a storing fluid. Sections of 2–3 μm afford satisfying morphologic and morphometric results. This method allows various arterial wall dimensions to be measured easily, and provides a suitable means to compare histometric values with SEM data derived from corrosion casts.
Cephalic neurulation in the mouse embryo analyzed by SEM and morphometry
Authors: Jacobson Antone G. , Tam Patrick P. L. 
Published: February 2005

AbstractA detailed account of mouse neurulation is given based mostly on SEM analysis over 20 hr of development. Many observations and measurements were made on staged living embryos and on embryos prepared for scanning and light microscopy to help deduce what mechanisms may contribute to neural tube formation. Each‐lateral half of the early cephalic neural plate makes a convex bulge, opposite to the way it must fold to form a tube. Underlying mesenchyme and matrix are reported to have a role in forming these bulges. Processes that form the tube must overcome this opposed folding and the forces that produce it. Cranial flexure begins long before tube formation. The flexure commences at the rostral tip of the cephalic neural plate, then the apex of the flexure migrates caudally to the mesencephalic region. Early appearance of this flexure imposes a mechanical impediment to tube closure in forebrain and midbrain regions. Tube closure begins in the cervical region exactly where the neural plate is reflected dorsally by a bend in the embryo. This bend may mechanically assist closure in this region. Cells of the mouse neural plate are reported to contain organized microfilaments and microtubules, and the plate cells appear to change shape (reduce apical area and increase cell height) in the same manner as that suggested in embryos of some other species to contribute to neural tube formation. Measurements show that the lateral edges of the cephalic neural plate elongate craniocaudally more than the midline of the plate through each period. This elongation could contribute to the folding of the plate into a tube. The progress of cranial ventral flexure pauses while tube formation occurs, but edge elongation continues, presumably contributing to tube formation. There is considerable increase in volume of the neural plate during tube closure, and cell proliferation and enlargement of daughter cells seem sufficient to account for this growth. Mitotic spindles are positioned to place the majority of the daughter cells into the long axis of the neural plate, so ordered growth may be the main mechanism of elongation of the plate in the craniocaudal direction, which in turn may assist in tube formation. Mouse cephalic neural plates appear overlying already segmented cranial mesenchyme according to previous reports, and neuromeres develop precociously in the open plates, where their positions correlate exactly with the underlying segmented mesenchyme.
Scanning electron microscopic study of arterial cushions in rats: A novel application of the corrosion‐replication technique
Authors: Casellas D. , Dupont M. , Jover B. , Mimran A. 
Published: February 2005

AbstractThe morphology and organ distribution of arterial cushions were studied in adult rats (body weight ranging from 200 to 500 gm) by scanning electron microscopic (SEM) observation of corrosion casts. Scanning electron microscopic observations of renal vascular casts were correlated with SEM views of the luminal surfaces of similarly fixed vessels; there was a striking similarity in shape, organ distribution, and dimensions between fixed arterial cushions and indentations at the surfaces of casts. Application of this technique to 11 different organs, some of which had never been studied by SEM before, revealed the occurrence of indentations at branching sites similar to those found in kidneys (and hence they were termed “cushions”). Our findings are in generally good agreement with previous light and transmission electron microscopic studies on rats. Our results support the view that arterial cushions are present throughout the vasculatures of the rat. A quantitative morphologic study of replicated branching sites related to “cushions” showed a great variability of the parent‐to‐daughter luminal diameter ratio (range 0.87–16.38) and of branching angles. A fruitful application of this technique to other laboratory animals may be anticipated.
Ultrastructural evidence for steroid‐hormone production in the adrenal of the marsupial, Isoodon macrourus, at birth
Authors: Gemmell R. T. , Singh‐Asa P. , Jenkin G. , Thorburn G. D. 
Published: February 2005

AbstractTo determine whether the adrenal gland of the bandicoot is actively producing steroid hormones at birth, the cellular structure was examined by electron microscopy, and the concentration of cortisol in the gland was determined by radioimmunoassay.Two distinct cell populations were seen in the adrenal gland. One group of cells possessed dark staining granules, normally observed in catecholamine‐secreting cells, and the second group contained large amounts of smooth endoplasmic reticulum and mitochondria with tubulo‐vesicular cristae. Both features are characteristic of steroid‐secreting cells. A concentration of 0.094 ng of cortisol per adrenal was determined by pooling glands from nine individual newborn bandicoots.This evidence of cortisol secretion from the bandicoot adrenal at birth indicates that, as in many eutherians, the marsupial adrenal may play an important role in determining the length of gestation.
Clonal proliferation of peritoneal exudate cells from New Zealand black mice: Age‐related changes
Authors: Murray Michael J. , Erickson Kent L. , Gershwin M. Eric 
Published: February 2005

AbstractProliferation and differentiation of peritoneal exudate colonyforming cells (PE‐CFC) were examined in BALB/c, C57BL/6, and NZB mice; NZB mice provided an experimental animal model for studies of autoimmunity. At 1 and 12 months of age, the number of PE‐CFC from NZB mice was significantly less than the number of PE‐CFC for other tested strains, whereas the number of clusters formed was reduced only in the older NZB mice. In contrast, 1‐ to 12‐month‐old BALB/c and C57BL/6 mice showed no significant age or strain‐dependent alterations in PE‐CFC. Although the latency period preceding colony growth remained constant for all strains and ages, significant variation in colony size was observed for NZB mice; the largest colonies were noted in the oldest group. We also observed age‐associated variations in colony morphology; therefore, age‐and strain‐dependent differences may exist in the differentiation or functional attributes of PE‐CFC subpopulations. The results specifically indicate that NZB mice have age‐related alterations in PEC proliferative and differentiation capacities.
Morphologic and functional studies of mouse hepatocytes in primary culture
Authors: Klaunig James E. , Goldblatt Peter J. , Hinton David E. , Lipsky Michael M. , Knipe Stephen M. , Trump Benjamin F. 
Published: February 2005

AbstractMouse liver cells in primary culture were evaluated by highresolution light microscopy (HRLM) and transmission electron microscopy (TEM). Cells after 2 hours of culture in L‐15 medium supplemented with 10% fetal bovine serum were spherical in shape, and were either individual or in small clusters of up to ten cells. Following 1 day in culture, hepatocytes were flattened and usually found in groups. Bile canaliculus‐like structures were apparent between hepatocytes. Tight junctions and desmosomes were also present along adjacent plasma membranes. Autophagic vacuoles were seen within the cytoplasm. After 2 days in culture, hepatocytes appeared more elongated and flattened than in earlier sampling periods. Both autophagic and clear vacuoles were seen in the cytoplasm. Mitochondria were present in a variety of shapes and sizes. Small bundles of microfilaments were frequently seen in the basal region of cross‐sectioned cells. From the fourth until the eighth day in culture, hepatocytes displayed further progression of the morphologic changes seen after 2 days. Nuclear elongation and the projection of cytoplasmic pseudoinclusions into the nucleus were also evident after 4 days. Cytoplasmic and nuclear changes were eventually observed in all hepatocytes by the eight day of culture. DNA synthesis in the cells during culture was investigated by autoradiography. The percentage of S‐phase labeled cells was 0.1% after 1 day of culture. The labeling index increased to 1.02%, 3.14%, and 5.88% after 2, 4, and 6 days of culture, respectively. Synthesis of albumin by the liver cells was also detectable during the first 8 days of primary culture. A gradual drop in albumin synthesis was noted with increased time in culture. The percentage of hepatocytes that histochemically stained for gamma glutamyl transpeptidase (GGT) progressively increased from 0.01% of the cells after 2 hours culture to 3.14% of the cells after 8 days of culture.
Comparative study of ultrastructures of the lateral‐line organs and the palatal taste organs in the African clawed toad, Xenopus laevis
Authors: Toyoshima Kuniaki , Shimamura Akitatsu 
Published: February 2005

AbstractThe fine structure of the lateral‐line organ and the palatal taste organ in the African clawed toad, Xenopus laevis, was examined by means of electron microscopy.The lateral‐line organ consisted of hair and accessory cells. The apical surface of a hair cell was studded with one kinocilium and 20 to 40 stereocilia. Synaptic bodies and subsynaptic cisternae were found in the cytoplasm of a hair cell adjacent to the synaptic contacts with the afferent and the efferent nerve endings, respectively. Crystalline bodies were observed in both the nucleoplasm and the cytoplasm of almost all hair cells.The palatal taste organ consisted of three types of cells: the taste, sustentacular, and the Merkel cells. The taste cells contained numerous dense‐cored vesicles which accumulated in close association with both the afferent synapses and the basal plasma membrane. The possibility was raised from the ultrastructural results that these vesicles had dual functions as both neurotransmitter and hormone. The existence of Merkel cells in the palatal taste organ suggested that this organ might function not only as a chemoreceptor but also as a mechanoreceptor.In spite of possible chemosensory function of the lateral‐line organ in Xenopus, its ultrastructure was significantly different from that of the typical gustatory organ, the palatal taste organ, in this animal.
Relationship between granule‐containing cells and blood vessels in the rat autonomic ganglia
Authors: Abe Hiroshi , Watanabe Hiroshi , Yamamoto Toshi Yuki 
Published: February 2005

AbstractGranule‐containing (GC) cells and related blood vessels in the superior cervical ganglion and the pelvic plexus of the rat were examined by light and electron microscopy of serial thin sections. In the superior cervical ganglion, GC cells formed many clusters of more than 20 cells. These clusters were supplied with dense networks of fenestrated capillaries, while the ordinary ganglion cells had continuous capillaries distributed more sparsely. Several continuous capillaries diverged from the networks in the GC cell clusters to join with capillaries around the ganglion cells. In the pelvic plexus, continuous capillaries with well‐developed pericytes were distributed similarly around the GC cells and the ganglion cells. Dense networks of fenestrated capillaries in the clusters were never seen. Based on these observations, the physiological significance of the GC cells was discussed.
The behavior of bursal lymphoid follicle‐associated cells after treatment with testosterone
Authors: Lupetti M. , Dolfi A. , Michelucci S. 
Published: February 2005

AbstractAdministration of androgens produces damage in lymphoid tissue and in the bursa of Fabricius. After IM administration of 5 mg of testosterone propionate (TP) beginning at hatching and continued during the following 4 days, a significant reduction in the bursal weights is observed. Histologically, an increase in the connective tissue is observed and cystic formations are also found. In all cysts examined, there is continuity of the cystic lumen with the free surface. The follicle‐associated epithelial (FAE) cells are on the bottom of the pseudocysts and form a separation between the pseudocystic cavity and the lymphoid tissue which is still further inwards. These cells do not lose their esterase activity, even though they are often flattened. Furthermore, they disappear in the pseudocysts deprived of lymphoid tissue. A new hypothesis is advanced that the FAE cells originate from the mesenchyme with differentiation in the histocytic line.
Ultracytochemical localization of guanylate cyclase in the oviduct of estrogen‐stimulated rat
Authors: Kang Yuan‐Hsu , West William L. , George Mariam 
Published: February 2005

AbstractMany reports have indicated that estrogens increase uterine guanosine 3′,5′‐cyclic monophosphate (cGMP)levels via increasing the activity of guanylate cyclase. In the present study, guanylate cyclase activity was studied cytochemically in the oviduct of immature rats 24 hours after one or two doses (20 μg/kg, subcutaneously) of diethylstilbestrol (DES), one dose per day. The reaction product indicating guanylate cyclase was localized in the plasma membrane of epithelial cells, endothelial cells, and smooth muscle cells of all DES‐treated animals, but was absent from those of the vehicle control immature rats. The Golgi saccules of secretory cells and the periciliary membrane of ciliated cells were stained for the enzyme 24 hours after the first and second dose of DES, but the activity seemed diminished 24 hours after the second dose. Likewise, reaction product indicating guanylate cyclase was more prominent in the plasma membrane of epithelial cells of animals treated with one dose of DES than those animals treated with two doses of DES. However, in the endothelial and smooth muscle cells, guanylate cyclase activity increased after two doses of the estrogen. Further, pinocytotic vesicles or caeolae in these cells were also strongly stained for the enzyme after one and two doses of DES. These findings confirm the suggestion that guanylate cyclase plays a significant role in the growth, differentiation, and function (secretion and transport) of the oviduct.
Light‐microscopic and microspectrofluorometric characterization of porphyrin‐containing astrocytes in mouse optic nerve
Authors: Terr L. I. , Weiner L. P. 
Published: February 2005

AbstractFluorescence spectroscopy has been employed to investigate the emission spectrum of unusual orange‐red fluorescence found in the mouse optic nerve. Comparison of the spectra obtained with those of a number of porphyrins used as standards (protoporphyrin, uroporphyrin, and coproporphyrins) shows that the autofluorescence excited at about 400 nm (Soret band) is due to the presence of a mixture of these or other porphyrins in the nerve. Phase contrast, dark‐field, and light‐microscopy techniques demonstrated that the fluorescence is emitted by dense, coarse inclusions in the cytoplasm of astrocytes. The inclusions also exhibit high activity of endogenous peroxidase, a heme (porphyrin)‐ containing enzyme, characteristic for process of phagocytosis. A possible particiption of these astrocytes in phagocytosis is delineated.