Porcine Antral Follicles Research Articles

Follicular fluid stimulation of progesterone secretion: time course, dose-response and effect of inhibiting de novo cholesterol synthesis.

This study extends our previous observations of follicular fluid stimulation of progesterone secretion by granulosa cells from immature porcine antral follicles in vitro. Granulosa cells were incubated with either charcoal-treated fluid from large porcine follicles or serum in TC medium 199. Within minutes of the addition of follicular fluid to the cells, enhanced progesterone secretion was observed. A second, more substantial enhancement of progesterone secretion was observed after an additional incubation of 24 to 48 h. As we were unable to detect significant amounts of progesterone within either freshly collected or incubated cells, follicular fluid appears to stimulate both the synthesis and secretion of progesterone rather than just the secretion of preformed progesterone. Inhibition of de novo cholesterol synthesis with an inhibitor of the conversion of 7-dehydrocholesterol to cholesterol, reduced progesterone secretion by cells incubated with serum to a greater extent than by cells incubated with follicular fluid. These studies suggest that follicular fluid may stimulate both de novo cholesterol synthesis and progesterone synthesis from preformed cholesterol. A dose-response test for follicular fluid stimulation of progesterone secretion indicated that 30% follicular fluid in TC medium 199 was as stimulatory as 50% follicular fluid. Ten percent follicular fluid was not stimulatory by itself, but in combination with 1 microgram of FSH/ml (ovine follicle-stimulating hormone), stimulated progesterone secretion to a greater extent than 30% or 50% follicular fluid alone.

Porcine granulosa and cumulus cell properties LH/hCG receptors, ability to secrete progesterone and ability to respond to LH

In order to compare the properties of isolated cumulus and granulosa cells, granulosa cells and cumulus cells surrounding oocytes were harvested from small (1–2 mm), medium (3–5 mm) and large (6–12 mm) porcine antral follicles and the number of LH/hCG receptors was measured by the binding of [ 125I]hCG. The ability of the cells to secrete progesterone in culture was examined in the presence and absence of hCG and LH. In 3 separate experiments of 1-h incubations at 37°C using cells harvested from medium-sized follicles, granulosa cells bound 10–15-fold more iodinated hCG than an equivalent number of cumulus cells. During a 2-day culture period, cumulus cells secreted less progesterone than granulosa cells from medium- and large-sized antral follicles ( p < 0.01). The potential of both cumulus and granulosa cells to secrete progesterone in culture increased as the follicle progressed from small to large size. Also, the ability of the oocyte to mature in culture increased with antral follicle size. Concurrently the ability of cumulus-oocyte complexes to form monolayers in culture decreased as the follicle matured. Cumulus and granulosa cells harvested from small- and medium-sized follicles responded similarly to LH and hCG with a stimulation in progesterone secretion after 2–6 days in culture.

Effect of FSH and HCG on progesterone secretion by cultured oocyte‐cumulus complexes and granulosa cells from porcine antral follicles: Influence of follicular development

AbstractOocyte‐cumulus complexes and granulosa cells were harvested from small (1–2 mm), medium (3–5 mm), and large (6–12 mm) porcine antral follicles and cultured for 2 and 3 days. The effects of various doses of purified hCG and human FSH on progesterone secretion and monolayer formation were examined. After a 2‐day culture period it was found that FSH was more effective in stimulation of progesterone secretion by cultured oocyte‐cumulus complexes than in granulosa cells harvested from small follicles (P &lt; 0.01), whereas hCG was more effective in stimulating progesterone secretion in granulosa cells than in oocytecumulus complexes harvested from large follicles. In contrast, after a 3‐day culture period, granulosa cells secreted more progesterone compared to oocytecumulus complexes under control conditions or in the presence of hCG or FSH. After 3 days both FSH and hCG stimulated progesterone secretion by oocytecumulus complexes and granulosa cells; however, the hormone effect was greater upon granulosa cells than oocyte‐cumulus complexes. After 3 days of culture in the case of both follicular cell types, there was a greater response to FSH in the case of cells harvested from small compared to large follicles. The reverse was true in the case of hCG responsiveness.Monolayer formation ability of oocyte‐cumulus complexes was greater in the case of complexes harvested from small and medium than complexes harvested from large follicles. Addition of hCG to the cultures led to a dose‐dependent decrease in monolayer formation by oocyte‐cumulus complexes harvested from all sizes of follicles.