Cytophotometric analysis of the cell population composition of the the preoptic area of the hypothalamus in the common frog

DNA contents in squashed cells of the adult frog hypothalamic preoptic region (HPR) were measured using the Feulgen and UV cytophotometry techniques. The histone-DNA ratio in the cell nucleus was determined by means of a combined Feulgen-heparin-Alcian blue staining procedure. The nuclei of the vast majority of HPR cells have a diploid DNA content. However, in cells of this group the mean values of DNA amount and the distribution range were always higher than those in hepatocytes used as a diploid standard. Such a heterogeneity in DNA content in the diploid part of HPR cell population could apparently suggest some differences in the nuclear chromatin arrangement to be always higher in spring before the frog spawning, and it seems to be characteristic of this type of cells. About 1 per cent of cells with hyperdiploid surplus of DNA (H2c cells) as well as of tetraploid cells (4c and 2c X 2 cells) is found in HPR in frogs sacrificed both in winter and in summer. The quota of these cells has no reference either to the frog's age or to the annual cycle. The fact that the mean DNA values in H2c and 4c cells are much higher than in the standard cannot be explained by the presence of different amounts of nuclear proteins only. It is suggested that at least some part of the highest DNA values may be due to an actual extra DNA synthesis in a small constantly existing pool of HPR cell population.     

Demonstration of the heterogeneity of the mast cell population on the basis of the mucopolysaccharide content.

From the aspect of its mucopolysaccharide content the mast cell population is not homogeneous. The pulmonary and heart muscle mast cells of the rat are alcian blue positive, the mast cells of the thyroid gland, lymph nodes, subcutaneous connective tissue, mesentery and peripheral nerve are safranin positive, whereas among the mast cells of the peritoneal cavity and the thymus there are both alcian blue and saffranin positive forms. The least acid mucopolysaccharides are in the mast cells of the peritoneal fluid, the mesentery and the lungs, whereas the most acid ones are in the mast cells of the lymph nodes, the subcutaneous connective tissue and the thyroid gland. There is a considerable difference between the two last mentioned organs. The mast cells of the subcutaneous connective tissue are end-product cells without amine or precursor turnover, whereas the mast cells of the thyroid gland incorporate and deliver amines, which may participate in the regulation of the host gland.     

Cytophotometric study of the DNA content in the cells of the preoptic area of the hypothalamus in hibernating common frogs

The DNA content in the squashed Feulgen stained cells of the hypothalamic preoptic region in wintering adult and juvenile frogs was measured cytophotometrically. The vast majority of hypothalamic cells studied showed diploid DNA contents. Only 0.9% of tetraploid cells (4c and 2c X 2 cells) was found in this region, both in adult and juvenile frogs. The incidence of tetraploid hypothalamic cells varied among the individuals studied. In some adult frogs as well as in some juveniles no tetraploid cells were detected. The data obtained do not confirm the age related increase in the mean DNA content in frog's hypothalamic cells population.     

Immunohistochemical localization of the transferrin receptor in the seminiferous epithelium of the rat

The transferrin receptor has been immunohistochemically localized in the seminiferous epithelium of the rat with a monoclonal antibody, MRC OX26, which recognizes the transferrin receptor glycoprotein. The receptor was detectable on mitotically and meiotically dividing germ cells and, less abundantly, on round spermatids. It was lost from germ cells during spermatid elongation and was undetectable on immature spermatozoa. The transferrin receptor was also present on Sertoli cells in the testes of immature animals and on Sertoli cells in the testes of aspermatogenic animals that had been irradiated in utero. It was not detectable on Sertoli cells in the testes of cryptorchid animals. These studies demonstrate that the transferrin receptor is abundant on dividing germ cells as well as dividing somatic cells.     

An ultrastructural study of the regenerating breast feather of the fowl

The developmental morphology of regenerating male breast feathers of the jungle fowl was studied at the ultrastructural level. The process of keratinization was observed in the three types of cells which form feather barbs: barbule cells, cortical cells, and medulla cells. Keratinization first became evident in the barbule cells and resembled the process of keratinization as observed in hair cortical cells and embryonic down feathers. Eventually the whole cytoplasmic area of the barbule cell was occupied by keratin. The barb cortex cells became keratinized in a similar fashion as the barbule cells but not until they were developmentally twice as old as the barbule cells. When keratinization was complete in these cells, the keratin was in the form of large agglomerates scattered in the cytoplasm. The barb medulla cells showed no obvious signs of keratinization until they were developmentally three times as old as the barbule cells. Keratin filament bundles were first seen near the plasma membranes of the medulla cells. Large empty vacuoles appeared in the cytoplasm which also contained moderate amounts of glycogen.     

Analysis of the Behavior of Mitochondria in the Ovaries of the Earthworm Dendrobaena veneta Rosa 1839

We examined six types of cells that form the ovary of the earthworm Dendrobena veneta ogonia, prooocytes, vitellogenic oocytes, trophocytes, fully grown postvitellogenic oocytes and somatic cells of the gonad. The quantitative stereological method revealed a much higher “volume density” of mitochondria in all of the types of germ-line cells except for the somatic cells. Fluorescent vital stain JC-1, however, showed a much higher oxidative activity of mitochondria in the somatic cells than in the germ-line cells. The distribution of active and inactive mitochondria within the studied cells was assessed using the computer program ImageJ. The analysis showed a higher luminosity of inactive mitochondria in all of the types of germ-line cells and a higher luminosity of active mitochondria in somatic cells. The OXPHOS activity was found in somatic cells mitochondria and in the peripheral mitochondria of the vitellogenic oocytes. The detection of reactive oxygen species (ROS) revealed a differentiated distribution of ROS in the different cell types. The amount of ROS substances was lower in somatic cells than in younger germ-line cells. The ROS level was also low in the cytoplasm of fully grown postwitellogenic oocytes. The distribution of the MnSOD enzyme that protects mitochondria against destructive role of ROS substances was high in the oogonia and in prooocytes and it was very high in vitellogenic and postvitellogenic oocytes. However, a much lower level of this protective enzyme was observed in the trophocytes and the lowest level was found in the cytoplasm of somatic cells. The lower mitochondrial activity and higher level of MnSOD activity in germ-line cells when compared to somatic cells testifies to the necessity of the organisms to protect the mitochondria of oocytes against the destructive role of the ROS that are produced during oxidative phosphorylation. The protection of the mitochondria in oocytes is essential for the transfer of healthy organelles to the next generation.     

Motile cells in the mucosa of the cloacal urodaeum and proctodaeum of the hen

Summary Motile cells (mast cells, granulocytes, lymphoid cells) are described in the mucosa of the cloacal urodaeum and proctodaeum of the female domestic fowl. Diffuse lymphoid tissue with lymphatic nodules occurs in the urodaeum at the ureteral ostium. Small local aggregations of lymphoid tissue can be observed in the mucosa of the proctodaeum. Cells originating from these sites penetrate the basal lamina of the epithelium and are then found between the epithelial cells.In the subepithelial layers the motile cells sometimes are in contact with each other. Mast cells (tissue basophils) form contact zones, resembling desmosomes or half desmosomes, with smooth muscle cells. In the mast cells three types of granules can be distinguished. Their ultrastructure is discussed in comparison with that in similar cells of the guinea pig.Dedicated to Professor Dr. med. M. Watzka in honor of his 75th birthday     

Multiplication of the dictyosome during the formation of autospores in the green alga Chlorococcum infusionum

Numerical changes in dictyosomes during the formation of autospores in a green alga, Chlorococcum infusionum, were investigated by electron microscopy. Two dictyosomes were seen near the nucleus in young vegetative cells. Four dictyosomes were seen in large mononucleate cells which appeared to enter mitosis soon. Binucleate cells contained 4 or 8 dictyosomes, the latter number being found in the large binucleate cells. Large tetranucleate cells contained 16-25 dictyosomes in each cell. Dictyosomes consisted of about 4 cisternae with a diameter of 0.4-0.6 micron in mono- to tetranucleate cells. Cytokinesis began with the formation of the septa during the third nuclear division, and 16 cells were finally formed. Dictyosomes did not increase in number in 8- and 16-nucleate cells. In septum-forming cells, dictyosomes were 0.6-1.0 microns in diameter, with 6-9 cisternae. A single dictyosome was included in each of the 16 resultant cells. These observations suggest that the dictyosomes multiply in association with the multiplication of the nuclei without correlation with formation of the cell wall or cytokinesis.     

Mast cells and cells producing alpha-endorphin in the mucosa of the antral section of the stomach

The distribution of mast cells, alpha-endorphine-producing cells (AER-cells) and argyrophilic cells in lamina propria of the antral mucosa was determined quantitatively in 13 normal men. The cells were detected by histochemical and immunohistochemical (PAP) methods. The form and site of AER-cells resembled those of mast cells and mucosal argyrophilic cells (in lamina propria). The authors assume that part of human gastric mucosal cells have argyrophilic properties and contain alpha-endorphine.     

Ultrastructure of the Testicular Interstitial Tissue of the Hagfish Eptatretus stouti

Ultrastructure of the somatic components of the testis of the Pacific hagfish was studied. Interstitial cells, equivalent to Leydig cells of higher vertebrates, containing smooth-surfaced endoplasmic reticulum and mitochondria with tubular cristae were found in the interstitial tissue, as well as leucocytes, fibroblasts and other cells of unknown role. Two kinds of somatic cells were observed in the testicular follicles: Sertoli cells and “stellate cells”. The significance of interstitial cells was discussed in relation to possible involvement in steroidogenesis.     

Development of the mammalian gonad: the fate of the supporting cell lineage

Sex determination in mammals is mediated via the supporting cell lineage in the fetal gonad. In the very early stages of gonadal development, the fate of the supporting cell population is critically dependent on the expression of the male-determining gene on the Y chromosome. If this gene is absent or fails to be expressed, or is expressed too late or in too small a number of supporting cells, all supporting cells (XX or XY) differentiate as pre-follicle cells and development proceeds along the female pathway. Supporting cells in which the male-determining gene is expressed in a timely manner differentiate as pre-Sertoli cells; given sufficient such cells, testis cords form and development proceeds in a male direction. If XX supporting cells are also present, a few may be recruited into the pre-Sertoli population and participate in testis cord formation. The subsequent fate of pre-follicle cells depends critically on interaction with the germ cell population in the developing gonad: absence of germ cells may lead to partial masculinization of the gonad, and/or to disappearance of the supporting cell component.     

Fine structure of the parotid gland in the pika and the volcano rabbit

The parotid glands of the pika and the volcano rabbit were examined by light and transmission electron microscopy. The acinar cells of the pika consisted of light cells containing basophilic granules of low density, while in the volcano rabbit the acinar cells consisted of light and dark cells containing acidophilic granules of moderate density. Intercalated duct cells were composed of light cells containing a few granules of moderate density. These segments of the two animals were similar in morphology. The striated duct cells in both species were composed of light and dark cells. Most of those in the pika contained a few moderately dense granules. In both animals, no myoepithelial cells were detected around the acini, intercalated ducts or striated ducts, while nerve terminals were observed among the adjacent acinar cells.     

Peroxidase activity in the epithelium of the digestive tract of the bullfrog, Rana catesbeiana

Peroxidase activity was examined cytochemically in the mucosal epithelium along the length of the digestive tract from the esophagus through the large intestine during the development of the bullfrog, Rana catesbeiana. In the tadpole of this species, cells with peroxidase activity were found abundantly in the esophagus, stomach, and large intestine; and the types of such cells differed according to the region: ciliated cells and mucous cells in the esophagus; ciliated cells in the stomach; and brush cells, absorptive cells, and goblet cells in the large intestine, respectively. After metamorphosis, however, peroxidase activity was observed exclusively in absorptive cells and goblet cells in the large intestine. Peroxidase activity was commonly demonstrated in apical vesicles or granules, to some degree in rough endoplasmic reticulum, and in some elements of the Golgi apparatus. Furthermore, reaction product was also found in mucus covering the luminal surface of such epithelial cells. These findings indicate that peroxidase-positive cells, which may have the ability to synthesize peroxidase as a secretory product, were distributed mainly in three regions of the digestive tract in tadpoles (esophagus, stomach, and large intestine), but were centered in one specific region, the large intestine, after metamorphosis. Concomitantly, the variety of types of peroxidase-positive cells decreased during metamorphosis. Our results indicate that some of the peroxidase in the digestive tract may have a secretory origin and may play a role in the defense against microorganisms.     

Endocrine cells of the mucous membrane of the fundus region of the stomach of hibernating rodents]

The gastric mucous membrane was studied in the hibernating animal Citellus erythrogenys in different seasons (during 7-8 months a year the animal is in hibernation and its digestive tract is not functioning). During hibernation the general amount of enterochromaffin-like cells decreases and their composition changes: the number of active cells diminishes and that of less active cells grows. Such dynamics of cells suggests the participation of enterochromaffin-like cells of Citellus erythrogenys in the regulation of gastric secretion (in rats and mice these cells contain histamine stimulating the mucous membrane glands). The amount of true enterochromaffin cells is not sufficiently changed and they seem to be not directly related with digestion but to be producers of serotonin which (together with serotonin of the brain) takes part in sustaining the mechanisms of appearance and supporting of winter hibernation.     

Immunohistochemical localization of taurine in the male reproductive organs of the rat.

The amino acid taurine has been implicated in several aspects of reproductive system physiology. However, its localization in these organs has not been previously analyzed. The aim of this study was to characterize its distribution in male rat reproductive organs by immunohistochemical methods. Taurine was localized in the smooth muscle cells of the tissues studied and in the skeletal fibers of the cremaster muscle. In the testis, taurine was found in Leydig cells, vascular endothelial cells, and other interstitial cells. No immunoreactivity was observed in the cells of the seminiferous tubules, either in germ cells at all spermatogenic stages or in Sertoli cells. However, peritubular myoid cells were immunostained. Most epithelial cells of the efferent ducts were immunolabeled, whereas the epithelial cells of the rete testis (extratesticular segments), epididymis (caput, corpus, and cauda regions), and ductus deferens were unstained. However, most epithelial cells from the intratesticular segments of the rete were immunopositive. Some cells identified as intraepithelial macrophages and lymphocytes, apical cells, and narrow cells were intensely immunolabeled. Regional differences in the distribution of these cell types along the ducts studied were also noted. The possible functional roles for taurine in these cells are discussed.     

Culturing the epiblast cells of the pig blastocyst

Summary Pig epiblast cells that had been separated from other early embryonic cells were cultured in vitro. A three-step dissection protocol was used to isolate the epiblast from trophectoderm and primitive endoderm before culturing. Blastocysts collected at 7 to 8 days postestrus were immunodissected to obtain the inner cell mass (ICM) and destroy trophectodermal cells. The ICM was cultured for 2 to 3 days on STO feeder cells. The epiblast was then physically dissected free of associated primitive endoderm. Epiblast-derived cells, grown on STO feeders, produced colonies of small cells resembling mouse embryonic stem cells. This primary cell morphology changed as the colonies grew and evolved into three distinct colony types (endodermlike, neural rosette, or complex). Cell cultures derived from these three colony types spontaneously differentiated into numerous specialized cell types in STO co-culture. These included fibroblasts, endodermlike cells, neuronlike cells, pigmented cells, adipogenic cells, contracting muscle cells, dome-forming epithelium, ciliated epithelium, tubule-forming epithelium, and a round amoeboid cell type resembling a plasmacyte after Wright staining. The neuronlike cells, contracting muscle cells, and tubule-forming epithelium had normal karyotypes and displayed finite or undefined life spans upon long-term STO co-culture. The dome-forming epithelium had an indefinite life span in STO co-culture and also retained a normal karyotype. These results demonstrate the in vitro pluripotency of pig epiblast cells and indicate the epiblast can be a source for deriving various specialized cell cultures or cell lines.     

Ultrastructure of the cardiac and pyloric glands of the gastric mucosa of the South African hedgehog,Atelerix frontalis

The cardiac and pyloric glands in the gastric mucosa of the South African hedgehog, Atelerix frontalis, are described. The cardiac area of the stomach contains proper cardiac glands and lacks undifferentiated fundic glands. The cardiac glands are simple tubular, coiled, and lined with columnar cells ultrastructurally similar to those of the gastric surface epithelium. Secretory granules with varying electron densities fill the apical cytoplasm of these cells. In contrast to other mammals, these glands lack mucous neck cells. The neck of the pyloric glands contains only a single cell type, whereas the basal regions of these glands contain “light” and “dark” cells. The secretory granules in the “dark” cells and the pyloric neck cells have a moderate electron density and often contain an electron dense core. An electron-lucent cytoplasm with numerous polysomes is characteristic of the “light” cells. Some “light” cells contain electron-dense granules in the apical cytoplasm. The presence of only neutral mucins in the cardiac gland cells denotes the absence of mucous neck cells. The acidic mucins within the pyloric neck cells seem to indicate that these cells are mucous neck cells, whereas the neutral mucins within the basally located pyloric gland cells show at least a partial functional difference from the pyloric neck cells. © 1993 Wiley-Liss, Inc.     

Efferent neurons of the auditory center in the midbrain of the frog Rana ridibunda

Individual cells which produce projections from the torus semicircularis in the frog have been visualized after injection of horseradish peroxidase (HRP) to various thalamic and isthmal areas. Labeled toral cells were observed if HRP had been injected to the posterodorsal areas of the thalamus or to the isthmal areas where lateral lemniscus fibers and cells of the premature lateral lemniscal nucleus are situated. Medium and large size cells in the rostrolateral torus semicircularis were mainly labeled. Thalamic injections of the HRP produced more labeled cells in the lateral part of the magnocellular nucleus, whereas isthmal injections produced labeled cells mainly in the lateral part of the laminar nucleus. A few HRP containing cells were observed in the principal nucleus of the torus. Specificity of the neuronal organisation of the auditory pathway in amphibians is discussed.     

Morphological characterization of stationary reticulum cells of the stromal in the mesenteric lymph node of the guinea pig

The large mesenteric lymph node taken from guinea pigs in a period of time ranging from the 10th day prepartum till the 26th day postpartum has been examined in order to study: the morphological features of the stromal stationary reticulum cells with particular regard to recognize their stages of development; the possible ontogenetic relationship between these cells during the maturation of the lymphoid tissue. Our data support the hypothesis that from local mesenchymal cells originates a pool of poorly differentiated reticulum cells that can give rise to stromal stationary reticulum cells (myofibroblast-like cells, fibroblast-like cells, pericyte-like cells and dendritic cells). These elements have a characteristic distribution pattern likely related to different local functional requirements.