The ontogeny of immunoreactive, endogenous FSH and LH in the rat ovary during early folliculogenesis.

Rabbit antisera to rat pituitary follicle-stimulating hormone (FSH) and to rat luteinizing hormone (LH) were used, in an immunocytochemical probe, to determine the ontogeny and distribution of immunoreactive, endogenous, intraovarian FSH and LH in immature rats. Ovaries from rats 4, 8, 12, and 21 days of age were studied. Both gonadotrophins were first immunodetectable on Day 8. In reactive primordial follicles, LH was restricted to the cytoplasm and nuclei of the surrounding follicle cells. In those follicles possessing both squamous and cuboidal follicle cells, i.e., transitional between primordial and primary, LH was found in both the cytoplasm and nuclei of both follicle cell types. In primary follicles, LH was no longer present in granulosa cells but was concentrated in germ cell cytoplasm. In contrast, in primordial follicles, FSH was restricted to the germ cell but was present in both the oocyte cytoplasm and germinal vesicle. In transitional and primary follicles, FSH remained within the oocyte cytoplasm and germinal vesicle but also became detectable within the cytoplasm and nuclei of granulosa cells. These findings raise some important new questions regarding the role(s) of the gonadotrophins in early follicular development.

Endothelial mitosis during the initial stages of corpus luteum neovascularization in the cycling adult rat.

The initial stages of neovascularization of the corpus luteum were studied in cycling adult rats using light-microscopic autoradiography. The aim of this analysis was to determine whether endothelial mitosis is a factor in this vascular growth and whether there are differences in the amount of mitotic activity in various regions of the ovary. Ovaries were examined at two time intervals: 1-2 hr and 7-8 hr following ovulation. Animals received an intraperitoneal injection of tritiated-thymidine 20 min prior to perfusion fixation of the ovaries. Autoradiographic demonstration of tritiated-thymidine labeling in endothelial nuclei was considered an indication of DNA synthesis preceding mitosis. The percentage of labeled endothelial cells in the ovaries at both time intervals varied according to the region of tissue examined and the stage of differentiation of that region. Stromal vessels were less heavily labeled than thecal vessels. Thecal vessels surrounding growing follicles were more heavily labeled than those surrounding atretic follicles. The heaviest labeling was seen in the developing corpora lutea 7-8 hr following ovulation. Minimal labeling was evident in the corpora lutea which were formed in previous cycles. A regional difference was also detected in the ovarian mesothelium. The portion of the mesothelium overlying ovulated follicles and developing corpora lutea had the greatest percentage of labeled cells. The major findings of this study were: endothelial mitosis was elevated in the initial stages of luteal neovascularization; the heightened endothelial labeling was confined to specific regions of the ovary; and mesothelium in close proximity to the developing corpora lutea also displayed heightened DNA synthesis.

Ovulation of ovarian implants in unilaterally ovariectomized rats.

Subcutaneous autografts of ovarian tissue were made in unilaterally ovariectomized adult rats and were examined by light microscopy at various times after implantation. The implants were surrounded by a dense connective tissue capsule. They were well vascularized and contained follicles in varying stages of development as well as in different stages of atresia. Oocytes and fresh corpora lutea indicated that grafts ovulated in the presence of the in situ ovary but that the number of ovulations and their frequency were reduced when compared to normal ovaries or ovaries grafted in bilaterally castrated animals. Ovulation results in the formation of a cyst that contains follicular fluid, the oocyte, and cumulus in the ovarian stroma. Macrophages are associated with the oocyte-cumulus complex but are not prominent in association with the fluid in the cyst. It is suggested that follicular fluid is retained owing to inefficient resorption mechanisms and that this coupled with occasional ovulations results in the formation and maintenance of the large cysts.

Polycystic ovarian grafts in cycling young rats.

Subcutaneous autografts of the hilar region of the ovary were made in unilaterally ovariectomized Sprague-Dawley rats at 35 days of age. At 90 days of age the grafts and in situ ovaries were examined. The ovarian grafts all exhibited follicular cysts whereas the in situ ovaries of the same animals did not. This cystic condition is considered the result of an ovarian lesion. The system is being examined as a potential model of polycystic ovarian disease and the ovulatory failure which develops with old age.

Serous cystadenoma formation in guinea pig ovaries.

Early stages in spontaneous development of serous cystadenomas in ovaries of Hartley strain guinea pigs have been examined by light and electron microscopy. Growth of these cysts from the rete ovarii is apparent as early as 10 days of age. Epithelial cords fill with fluid to form dilated tubules lined with a simple columnar epithelium. While some cells of the rete and early cysts exhibit tufts of cilia, none shows signs of exocrine secretory activity. Examination of the permeability of cystic and noncystic rete to the tracer horseradish peroxidase indicates that tracer can pass through the intercellular space of the epithelium at all stages of development studied. Investigation of three age groups suggests that cystogenesis is a gradual process involving no marked alteration in cell structure.

Serous cysts of the aging guinea pig ovary. III. Permeability of the cyst epithelium to lanthanum and horseradish peroxidase.

The permeability of the epithelium lining serous cysts of the guinea pig ovary was examined using lanthanum and horseradish peroxidase (HRP). Both lanthanum and HRP introduced at the luminal surface of the cyst penetrated to the basal region filling caveolae in both lateral and basal cell surfaces. Within three minutes of vascular infusion of HRP, the tracer was detected between epithelial cells and in caveolae on their lateral and basal surfaces but not associated with intracellular organelles. There was no change in the intracellular distribution of HRP after ten minutes. It was concluded that the epithelium was permeable to the tracers within this time period but that pinocytosis and transport of these tracers through the epithelial cell were not demonstrated.

Serous cysts of the aging guinea pig ovary. II. Scanning and transmission electron microscopy.

Ovarian cysts which developed spontaneously from the rete ovarii in the ovaries of guinea pigs have been examined in 1- and 2-year-old animals by scanning and transmission electron microscopy. Two cell types have been described, a tufted cell with numerous motile cilia and a non-tufted cell with a solitary cilium. While the non-tufted cell exhibited numerous smooth coated vesicles in its lateral and basal regions, no signs of secretion to the lumen of the cyst have been seen and occluding junctions have not been observed.

Serous cysts of the aging guinea pig ovary. I. Light microscopy and origin.

Ovaries from guinea pigs of different ages have been examined by light microscopy. Serous cysts measuring between 1 mm and 2.5 cm are present in all animals over one year of age. The cysts are fewer in number and size at six months, are least developed at ten weeks and are not apparent in the near-term fetus. The cysts arise from the rete ovarii. They are lined with a simple cuboidal to columnar epithelium composed of cells bearing solitary cilia or tufts of cilia. The structure and origin of these cysts is discussed and compared with what is known of the human serous cystadenoma.

Drug biotransformation in microsomes from the fetal stumptailed macaque, Macaca arctoides: hepatic N-demethylation.

The kinetics of the N-demethylation of benzphetamine, ethylmorphine, meperidine, and methadone have been studied in microsomes isolated from livers of the fetal stumptailed macaque (Macaca arctoides) during the last third of gestation. The apparent KM for each substrate did not change during this time period. Values were similar to those from livers of adult African green monkeys. The Vmax for each substrate, when expressed per mg of microsomal protein, did not change during the last third of gestation. N-demethylase activity (Vmax) per g of liver increased during the last third of gestation, as did the content of microsomal protein, cytochrome P-450 concentration, and liver weight. The amount of cytochrome P-450 per g of liver was greater in whole homogenates of the left physiological lobe than in those of the right physiological lobe of fetal liver obtained near term; no differences occurred in whole homogenates of the separate lobes of adult liver. This observation suggests that a differential capacity for drug (and possibly steroid) metabolism may exist between the two physiological lobes of fetal liver.

Ultrastructure of the developing fetal hepatocyte of Macaca arctoides: a proposed model for studies of fetal drug metabolism.

The ultrastructure of the hepatocyte of the fetal stumptail monkey was examined with the aim of defining a possible model for studies of fetal drug metabolism. Hepatocytes from fetuses of 80 and 160 days gestation, as well as from one animal one week of postnatal age, were examined and compared to human fetal hepatocytes at 12 and 16 weeks gestation. Marked variation was observed in the amount of lipid and the distribution of organelles within the cytoplasm of the hepatocyte in the monkey population. These differences were attributed to genetic variation. Two changes were seen which correlated with developmental age. The amount of hemopoietic tissue decreased and the amount of smooth endoplasmic reticulum increased as the animal matured. The problems of genetic variation and the relative number of hepatocytes at different stages of development were discussed relative to the use of this animal as a model for fetal drug metabolism studies. Attention to both of these problems is considered necessary for the interpretation of biochemical data in future studies.