Fine structure of the corpus luteum of the autografted ovary in the rat

Summary The rat ovary has been transplanted successfully to subcutaneous tissue areas by several investigators. Light microscopy has revealed that corpora lutea in ovarian autografts are formed by luteinization of intact follicles and contain entrapped ova. In the present study, corpora lutea from autografted ovaries in castrate rats were obtained at metestrus and examined electron microscopically to determine whether their cellular morphology correlated with the normal progesterone levels in these animals. Cellular features usually accepted as regressive were apparent. The findings suggest either structural luteolysis is occurring before functional luteolysis or that the adrenal has increased steroidogenic activity in the castrate with ovarian autografts to account for the normal progesterone levels.Supported in part by USPHS Grant T01-DE00241-04The authors wish to thank J. Canale and Y. Tablada for technical, G. Kerimian for photographic, and M.A. Anderson for secretarial assistance     

Macrophages in the interstitial tissue of the rat testis

Summary Macrophages were identified in the intertubular tissue of the rat testis by loading animals with a particulate vital dye (trypan blue or India ink) and by localizing immunocytochemically a macrophage membrane antigen (MRC W3/25). Leydig cells were identified by the histochemical staining reaction for 3-hydroxysteroid dehydrogenase activity and by a monoclonal antibody. Macrophages were scattered in the interstitial tissue closely attached to and mixed with the Leydig cells. They were never found in the seminiferous tubules. The macrophages comprised about 25% of all the cells in the interstitium. Double staining with a vital dye and a marker antibody showed that all the phagocytosing cells were macrophages and that the Leydig cells did not take up vital dyes. Double staining for the demonstration of the 3-hydroxysteroid dehydrogenase activity and the macrophage antigen likewise revealed two distinctly different cell populations. Crude Leydig cell preparations obtained by collagenase treatment of the testis contained macrophages (12–14%). Macrophages were present throughout the postnatal prepuberal development of the testis. Their density was increased in the cryptorchid and irradiated testis.     

Fine structure and origin of the tunic of Perophora viridis

The fine structure of the tunic of a typical ascidian was investigated because of the cellulose-like polysaccharide known to occur in its substance. The glycoprotein mantle does contain filaments very much like plant cellulose in morphology. Tunicin filaments are 35–50 Å in diameter, often beaded, and of indeterminate length. Histochemical evidence that they are composed of cellulose is given here and past chemical and physical studies on the unusual ascidian polysaccharide are reviewed. Moreover, we present here for the first time direct autoradiographic evidence that epidermal cells are involved in the synthesis and secretion of tunicin. Tritiated glucose is immediately incorporated into the Golgi zone of epidermal cells and labeled product appears in the tunic at later intervals. The fine structure of the epidermal cell is described in detail. Unlike the rather moribund appearing vanadocyte that wanders through the tunic, the epidermal cell has well-developed cytoplasmic organelles and a large vesicular nucleus. The granular endoplasmic reticulum is abundant and the Golgi complex is highly developed. It seems likely that the lamellae and vesicles of the Golgi complex are involved in the production of the tunic sugar and that tunic proteins of as yet unknown nature are produced by the ergastoplasm. Further investigation of the ascidian mantle should be of interest because of the possibility that cellulose is a more general component of glycoprotein surface coats in animals than has heretofore been recognized.     

Alteration of GABA levels in ovary and fallopian tube of the pregnant rat

The concentration and the total quantity of gamma-aminobutyric acid (GABA) were determined in ovary and Fallopian tube of the rat on day 3, 7, 14 and 21 of pregnancy and the values were compared with a diestrous control group. In ovary, both GABA concentration and total GABA content gradually elevated up to day 14 of gestation but, thereafter, the diminution of the two parameters was observed. The GABA concentrations in Fallopian tube were found to be strongly reduced during pregnancy, and the total amount of the amino acid in this organ also decreased markedly. The significant alterations of GABA levels in both organs suggest a possible correlation between the functional status and GABA content of ovary and Fallopian tube of the pregnant rat.     

Studies of the fine structure of ovarian interstitial tissue

Summary The post-natal evolution of thecal gland in the domestic fowl has been explored, and a hypothesis for this development is proposed. It is suggested that the surface epithelium of the ovary forms crypts and submicroscopic clefts (ingrowing cords) which contribute with epithelial elements required for the regeneration of some of the ovarian elements, including the thecal glands. Complexes of these ingrowing epithelial cells are forming small islets which, after hormonal stimulation, are transformed into well defined structures, the thecal glands, with a specific function, viz. steroid bio-synthesis.     

Studies of the fine structure of ovarian interstitial tissue

Summary The fine structure of the thecal gland of the domestic fowl, is described for the first time. In the fowl, the glands are located as islets of lipid-laden cells in the theca interna and also in the interfollicular regions. They appear as well defined structures, organized like endocrine glands, quite different from the surrounding theca interna cells. Each gland is composed of two different cell types, the steroid-producing cell, and a cell type never described before, named the enclosing cell. Both cell types are surrounded by a common, distinct basal membrane. The steroid-producing cells are characterized by their content of organelles typical of steroid-producing cells in other organs. The enclosing cells are char cterized by their peripheral location within the gland and their membranous contact with the steroid-producing cells, long processes with desmosomes and their relation to the nerve fibers. They do not contain the organelles typically found in steroid-producing cells. So far, the real function of the enclosing cells is unknown. The following structures are demonstrated in ovarian steroid-producing cells of the fowl for the first time: cytoplasmic microtubules and filaments, intramatrical lipid-like droplets, attachment devices, the polarity of the steroidproducing cells of the thecal gland.     

Studies of the fine structure of ovarian interstitial tissue

Summary The fine structure of ovarian steroid-producing cells of the domestic fowl as seen after administration of steroids is described. Diaethylstilboestrol, estradiol and hydroxyprogesterone were given as intramuscular injections for a 28-days period. The main cytoplasmic changes of the steroid-producing cells were an increase in the number and the size of lipid droplets due to a possible expansion of the endoplasmic reticulum and a confluence of the smooth endoplasmic reticulum and the lipid droplets. The mitochondria became paler, markedly reduced in size and number, and contained less cristae. The Golgi apparatus became smaller and tended to disappear. The most prominent nuclear changes were irregular outline of the nuclear membrane, shrinkage of the nucleus, formation of pseudo-inclusions, decreased number of nuclear bodies with a tendency to vacuolization and small nucleoli. These alterations have never been demonstrated in ovarian steroid-producing cells before, and they are consistent with atrophic changes observed in steroid-producing cells in other organs. The present study substantiates the view that the thecal gland must be concerned with endocrine function. The possible functions of the different cell types of the thecal gland are discussed.     

The three-dimensional cytoarchitecture of the interstitial tissue in the rat kidney

Summary The cytoarchitecture of the interstitial tissue of the rat kidney was studied by combined scanning and transmission electron microscopy. The renal interstitium is composed of an elaborate network of stellate sustentacular cells. In the cortex, sustentacular cells radiate thin branching processes to form a fine reticulum, which supports intertubular spaces. In the medulla, these cells extend thick processes horizontally along the basal surfaces of the thin limbs or vasa recta, reinforcing their attenuate walls. The horizontal processes connect with each other at their terminals, compartmentalizing the interstitial space into thin layers. The medullary sustentacular cells contain abundant small lipid droplets. The network of sustentacular cells houses vasa recta, keeping them in parallel position to each other and to the tubules. The arterial vasa recta are accompanied by pericytes, which frequently contain lipid droplets larger in size than those in the sustentacular cells. Venous vasa recta extend numerous basal microvilli, which anchor the venous wall to adjacent tubules or vessels. Numerous free cells, round in shape, are found in the sustentacular cell network, especially in the cortex. They consist of macrophages and occasional lymphocytes. Some macrophages extend long pseudopodia, while others make intimate contact with lymphocytes, suggesting their high level of activity.     

Cellular origin of prolonged induction of ornithine decarboxylase in the rat ovary

The temporal changes of ornithine decarboxylase (ODC) activity were investigated in the immature rat ovary following a single subcutaneous injection of pregnant mare serum gonadotropin (PMSG). A dose-response relationship was established. Maximal ODC activity was obtained at a dose of 25 IU of PMSG. This increase in ODC activity was accompanied by an increase of ovarian weight before reaching a maximum. A 250-fold increase of ODC activity was observed 1 day following a single dose of PMSG (50 IU). The enzyme specific activity only returned to the control level 4-5 days after hormone treatment. Immunoreactive ODC in immature, PMSG-primed rat ovaries and in heavily luteinized rat ovaries was localized utilizing the immunoperoxidase method and an antibody to ODC. Immunoreactive enzyme was confined to the cytoplasm of the granulosa cells but was not present in luteal cells. Thecal cells showed only weak immunostaining. This study provides clear evidence that the granulosa cell is the unique source of ODC activity in response to PMSG treatment. Furthermore, these data support the concept that polyamines play a role in granulosa cell proliferation and hence follicular development.