| Abstract: | The effects of cell plating density on granulosa cell sensitivity to follicle-stimulating hormone (FSH) were investigated, using a serum-free culture of cells obtained from immature, estrogen-treated rats. The cells were incubated at densities of 0.25 to 5 X 10(5) cells/dish with increasing concentrations of FSH for 2 days, and medium estrogen and progestin accumulation were measured by radioimmunoassay. Per-cell estrogen and progestin production rose with increasing FSH concentration and cell density up to 2 X 10(5) cells/dish. At a higher density (5 X 10(5)/dish), per-cell estrogen production fell; progestin production remained constant, although the major progestin produced was no longer progesterone, but rather its metabolite, 20 alpha-hydroxy-progesterone. The effects of changing cell density could not be accounted for by medium steroids or cytotoxic substances. It is concluded that in vitro plating density can markedly affect granulosa cell sensitivity to FSH. In vivo, changing intrafollicular cell densities may thus affect the ability of the whole cell complement to respond to gonadotropin. |
