Progesterone and Estrogen Secretion by Cultured Monkey Ovarian Cell Types: Influences of Follicular Size, Serum Luteinizing Hormone Levels, and Follicular Fluid Estrogen Levels*

Publisher Website
Google Scholar
Abstract
Rhesus monkeys were laparotomized before and during the LH surge, and the thecal layer, stroma, and granulosa cells were removed and cultured for 8 days, separately or together, in the presence or absence of 5 × 10-7 M testosterone. In each experiment (n = 30), estrogen and progesterone were measured in the follicular fluid and serum immediately before follicular harvest. The oocyte was harvested from the largest (presumed preovulatory) follicle present; its degree of maturity was determined using a stereomicroscope, followed by culture of the oocyte for 2 days. Follicles containing granulosa cells which failed to attach and grow, or degenerated oocytes (at the time of harvest or degenerated in culture) were not used and were designated atretic. After initiation of the LH surge, there was a significant rise in follicular fluid progesterone and estrogen levels, with estrogen levels reaching a peak at the time of the LH surge. One day after the LH surge, follicular fluid and serum estrogen levels dropped sharply, while follicular fluid progesterone levels continued to rise. Before the LH surge, granulosa cells from 3- to 6-mm as well as from 6- to 8-mm follicles secreted low levels of progesterone (2–10 ng/follicle·day) throughout the culture period and failed to luteinize morphologically. During the early part of the LH surge, there was an increased ability of granulosa cells to secrete progesterone in culture (600–1000 ng/follicle·day) and luteinize morphologically. At the time of the LH surge, the granulosa cells secreted high levels of progesterone (1000–2000 ng/follicle·day) with maximal morphological luteinization. Estrogen secretion by granulosa cells cultured in the absence of androgen substrate was low (3–20 ng/follicle·day) whether the cells were harvested before or during the LH surge. Thecal progesterone secretion was low before the LH surge (3–10 ng/follicle·day) and increased to 200–800 ng/follicle·day during the LH surge. Thecal estrogen secretion was low before the LH surge (4–20 ng/follicle·day) but increased to levels of 60–400 ng/follicle·day during the LH surge, with the highest levels occurring on the day of the LH surge. There was a sharp decline in thecal estrogen secretion 1 day after the LH surge. Incubation of theca plus granulosa cells obtained before the LH surge brought about a 1.8- to 2.4-fold increase in estrogen secretion above that secreted by either cell type alone. During and after the LH surge, incubation of theca and granulosa cells together failed to show more than an additive effect upon secretion of estrogen. The addition of 5 × 10-7 M testosterone markedly increased the ability of granulosa cells to secrete estrogen; testosterone augmentation of estrogen secretion was more pronounced if the granulosa cells were harvested during the LH surge than if they were obtained before the LH surge. The addition of testosterone to thecal cultures did not markedly augment estrogen secretion. Incubation of stromal tissue mixed with follicles less than 0.5 mm secreted estrogen, and this ability was increased during the LH surge. The addition of stromal tissue to either theca or granulosa alone did not have any stimulatory effect upon estrogen secreted into the culture medium. It may be concluded that granulosa cells must be exposed to the LH surge in order to luteinize in culture and maximally convert testosterone to estrogen. The theca layer increases its ability to secrete estrogen and progesterone during the LH surge. Theca and granulosa have the potential to interact in secreting estrogen in vitro before the LH surge, followed by a decline in the ability to interact during the LH surge.

This publication has 12 references indexed in Scilit: