Chemotactic and mitogenic activities of granulosa cells in developing follicles

Chemotactic and mitogenic activities of granulosa cells in developing follicles were studied. Immature rats were subcutaneously injected with 20 IU of pregnant mare's serum gonadotrophin and killed at various intervals after injection. The ovaries were removed and granulosa cells were isolated and cultured in a serum-free medium supplemented with insulin, transferrin and hydrocortisone. Chemotactic and mitogenic activities in the conditioned medium were determined. Our results demonstrated that in addition to mitogenic activity, chemotactic activity was also expressed in the conditioned medium of granulosa cells. Both activities increased with the maturity of follicles. A gel filtration analysis revealed that there were two peaks showing both mitogenic and chemotactic activities with a molecular size smaller than 5000. These peaks had various sensitivities to heat and trypsin treatment. In addition, the active component of both peaks was organic solvent-extractable. A thin-layer chromatography analysis indicated that the lipid component was not prostaglandin, estradiol or hydrocortisone.