On the histogenesis of the ovarian interstitial gland in rabbits. I. Primary interstitial gland

Growth and development of the ovary and small follicle pool from mid fetal life to pre-puberty in the African elephant (Loxodonta africana)

Background

Follicle numbers and developing ovarian morphology, particularly with reference to the presence of interstitial tissue, are intimately linked within the ovary of the African elephant during the period spanning mid-gestation to puberty. These have not been previously quantified in any studies. The collection of 7 sets of elephant fetal ovaries between 11.2 and 20.2 months of gestation, and 29 pairs of prepubertal calf ovaries between 2 months and 9 years of age during routine management off-takes of complete family groups in private conservancies in Zimbabwe provided an opportunity for a detailed study of this period.

Results

The changing morphology of the ovary is described as the presumptive cortex and medulla components of the fetal ovary settled into their adult form. Interstitial tissue dominated the ovary in late fetal life and these cells stained strongly for 3β–hydroxysteroid dehydrogenase. This staining continued postnatally through to 4.5 years of age suggesting continued secretion of progestagens by the ovary during this period. The considerable growth of antral follicles peaked at 28% of ovarian volume at around 16.7 months of fetal age. The numbers of small follicles (primordial, early primary and true primary), counted in the cortex using stereological protocols, revealed fewer small follicles in the ovaries of animals aged 0 to 4.5 years of age than during either late fetal life or prepubertal life.

Conclusions

The small follicle populations of the late-fetal and prepubertal ovaries of the African elephant were described along with the changing morphology of these organs. The changes noted represent a series of events that have been recorded only in the elephant and the giraffe species to date. The expansion of the interstitial tissue of the fetal ovary and its continued presence in early post natal life may well contribute to the control of follicle development in these early years. Further research is required to determine the reasons behind the variation of numbers of small follicles in the ovaries of prepubertal calves.

Ovarian cancer, Part I: Biology

The ovary is among the more complex organs of the body and its functions are achieved by numerous cell types. All of these cell types have some tendency to undergo malignant transformation, but the vast majority of ovarian cancers are believed to be the result of malignant transformation of the ovarian surface epithelium. The concept that most ovarian cancer arises from this modified peritoneal mesothelium is credited to Sir Spencer Wells in 1872. Ovarian cancer is the most frequently fatal gynecologic malignancy, and approximately 20,000 cases per year are diagnosed in the United States. Progress in understanding the biology of this disease, including factors involved in its etiology, progression, and tendency to change from a relatively chemotherapy-sensitive tumor to one with marked drug resistance, has been slow. In this review, the complex features of the normal ovarian surface epithelial cells are considered in relation to the etiology and progression of the disease. The hypothesis that incessant or repetitious ovulation contributes to the initiation of the disease is explored in detail based on experimental data, epidemiologic information, and the potential for antioncogene inactivation in this interesting cell type. Lastly, based on the experimental data available, potential mechanisms of resistance to platinum, the cornerstone of aggressive ovarian cancer therapy, are discussed, as are approaches to overcoming drug resistance. It is hoped that the reader will be left with the feeling that the pace of our understanding of the biology of ovarian cancer is increasing at such a rate that answers to the questions of etiology and why chemotherapy often fails will be known in the foreseeable future.

Development of the ovarian surface and associated germ cells in the human fetus. A correlated study by scanning and transmission electron microscopy

The ovarian surface and associated germ cells have been studied in human fetuses from 12 weeks of age until near term, using light, TEM and SEM techniques. The surface epithelium and related cords proliferate extensively, especially at midterm. The cords of the ovarian cortex appear to be linked with ingrowths from the surface epithelium, and both structures have a common basal lamina. Germ cells are always interspersed among the somatic cells of the surface epithelium and associated cords. These results indicate that both the proliferating cords and surface epithelium may contribute to the formation of early follicles. Furthermore, the occurrence, of elements having some of the features of primitive steroidogenic cells in the regions of cord-surface epithelium continuity, suggests that both structures (surface epithelium and cords) contribute somatic cells, which in addition to becoming granulosa cells, might also contribute to the provision of primitive interstitial cells. Gonocytes tend to migrate through the developing ovarian tissue towards the surface where they become extruded into the peritoneal cavity. This phenomenon might contribute to the reduction in the number of germ cells at birth and parallels the atretic processes within the ovary.

Immunofluorescent localization of the female sex steroids in the porcine ovary

Antibodies against progesterone 20-(o-carboxymethyl) oxime and oestrone 17-(o-carboxymethyl) oxime have been applied to porcine ovaries as the first layer in the indirect immunofluorescent technique. In the Graafian follicles, both steroids have been demonstrated within single cells of the theca interna. In the corpora lutea, the same steroids were found in the cells assembled at the periphery of the organ, as well as around the large vessels. Degenerating cells present in the corpora albicans revealed positive immunofluorescence together with distinct autofluorescence. Similarly, the atretic follicles and fragments of the interstitial gland showed both immunofluorescence and autofluorescence. The immunofluorescent localization of steroids was confirmed by the similar distribution of sudanophilic substances. However, the differentiation between the two hormones investigated was not certain.

Unusual arrangement of agranular endoplasmic reticulum in the interstitial cells of the cat ovary

An unusual arrangement of agranular endoplasmic reticulum in the interstitial cells of the cat ovary is described. The structural unit of this arrangement in cross section consists of five membranous sacs (800 to 900 A long and 250 to 350 A wide) radially coverging toward a microtubule. The sacs are separated from each other by three angles of 60 degrees and two of 90 degrees. In longitudinal section, the sacs appear to be long parallel cisternae. The geometric, radial arrangement seems to arise from a gradual incurvation and convergence of parallel units in these membranes. The microtubules may act as guides for the polarization and resulting unusual arrangement of the membranes. The purpose of such polarization may be related to a change from protein to steriod synthesis in these cells.