Gonadotropin stimulation of steroidogenesis and cellular dispersion in cultured porcine cumuli oophori

The relationship between cellular dispersion and steroidogenesis was studied in culture using oocyte-cumulus complexes harvested from porcine follicles. The cells were cultured in modified TC 199 containing pig serum for one to two days. When oocyte-cumulus complexes were cultured in the absence of hormone the oocytes resumed meiosis, the cumulus cells grew out forming monolayers, and progesterone accumulation was low. Addition of ovine LH, purified human LH, or purified human FSH stimulated expansion of the cumulus mass as well as enhanced progesterone accumulation. Oocyte maturation was not affected by the hormones. In absence of hormone, oocyte-cumulus complexes obtained from large (6–12 mm) follicles showed increased cellular dispersion and higher progesterone accumulation as compared to complexes obtained from medium-sized (3–5 mm) follicles.