The Production of Progesterone, Androgens, and Estrogens by Granulosa Cells, Thecal Tissue, and Stromal Tissue from Human Ovaries in Vitro *

Abstract

The concentrations of steroids in antral fluid, the number of granulosa cells, the status of the oocyte, and the diameter of each follicle were determined in human ovaries so that follicles at each stage of the menstrual cycle could be classified as large (greater than or equal to 8 mm diameter) or small (less than 8 mm diameter) and healthy or atretic. The granulosa cells and thecal-enriched tissue from each follicle and the stromal tissue from each ovary were cultured for 6 days in vitro. The amounts of progesterone (P), androstenedione (delta 4), testosterone, dihydrotestosterone, estrone, and estradiol (E2) generated by the different tissues were measured on days 0, 2, 4, and 6 of culture. It was found that granulosa cells, thecal tissue, and stromal tissue all have the biosynthetic capacity to produce P, delta 4, testosterone, dihydrotestosterone, estrone, and E2. No individual steroid-secreting compartment of the ovaries studied, whether part of the follicle or of the stroma, had the exclusive capability of producing any of the above-named steroids at any stage of the menstrual cycle or at any stage of antral follicle growth or atresia. Although the steroids produced by the human follicle appear not to be unique to any one cell type, the patterns of steroidogenesis by the granulosa and thecal compartments differ from one another and from the stroma throughout follicular maturation and atresia. During follicular development, granulosa cells produce large amounts of E2 and small amounts of delta 4. During the preovulatory phase, cells from large follicles (greater than or equal to 8 mm diameter) differentiate from an estrogen-secreting state into a P- and, to a lesser extent, an delta 4-secreting one. By contrast, during follicular atresia, granulosa cells continue to synthesize delta 4, but their capacity to synthesize estrogen is substantially reduced. Furthermore, granulosa cells from atretic follicles are incapable of transforming from an androgen-secreting state into a P-secreting one in tissue culture. During follicular growth, thecal tissue secretes about 2--3 times more delta 4 than E2. By contrast, during follicular atresia, thecal tissue retains its capacity to synthesize delta 4 but loses much of its capacity to synthesize E2. The in vitro capacity of thecal tissue to produce steroids exceeds that of the stroma (on a per weight basis) from 2- to 500-fold. Thecal tissue from healthy but not from atretic follicles is capable of differentiating from an androgen- and estrogen-secreting state to a predominantly P-secreting one in tissue culture. It is postulated that although steroid synthesis may not be rigidly compartmentalized during follicular development, appreciable amounts of the steroids secreted by the granulosa and theca may enter different compartments before leaving the ovary...

Follicle stimulating hormone effects on immature human oocytes: In vitro maturation and hormone production

“…Tsang et al found that the granulosa cells produced little or no androgen, even with FSH added to the culture medium (23). However, McNatty et al found that P, E2,'T, and androstenedione did accumulate in the medium of granulosa cells cultured in vitro and proposed that the granulosa cells of most follicles were capable of de novo synthesis of all of these steroids (24).…”

Structure-Function Relationships in the Wall of the Ovarian Follicle

“…Functional studies of follicular epithelium in vitro have generally shown that these cells possess an aromatase system capable of converting androgen to oestrogen, but, with the exception of human follicles (McNatty et al 1979), little or no ability to synthesize androgens. However, they are capable of synthesizing progesterone in vitro, a capacity which is greater in preovulatory follicles, particularly after the stimulus of an LH surge or in response to LH added to the medium (see Richards 1980).…”

“…Whether any significant oestrogen production occurs in the theca is less certain, although there are data in the pig (Rodway et al 1975;Stoklosowa et al 1978), Rhesus monkey (Channing and Coudert 1976) and man (McNatty et al 1979) to suggest that this may be so in some species.…”

“…While it is unlikely that the barriers between the theca and the follicular epithelium would present any serious impediment to the diffusion of androgens, it might be predicted that this would be a very 'leaky' route of transfer, with substantial diversion into the blood. There are, in fact, several lines of evidence to support the suggestion that appreciable amounts of theca-derived steroids do enter the blood stream directly (McNatty et al 1979). Now that techniques are available for the independent study of thecal and follicular epithelial cells in vitro (Moor 1977;Fortune and Armstrong 1978), prospects for obtaining a better understanding of the functional interactions between these layers appear promising.…”

Analysis of testosterone pulsatility in women with ovulatory menstrual cycles

“…These androgens are transferred to the preovulatory granulosa cells, where the androstenedione and testosterone are aromatized to estrone and estradiol by 17-b-hydroxysteroid dehydrogenase type I, stimulated by FSH (9). The ovarian androgen production and its conversion to estradiol are essential to the physiologic ovulatory process, and an insufficient androgen production at the follicular phase can lead to anovulation (10).…”