Isolated guinea pig adrenocortical cells in vitro: morphology and steroidogenesis in control and ACTH-treated cultures.

Isolated guinea pig adrenocortical cells were maintained in long-term culture in order to perform sequential experiments on the same cell populations. The cells produced fluorogenic steroids, shown by thin-layer chromatography to be at least aldosterone, cortisol, and corticosterone. In addition, they increased production of these steroids when treated with either ACTH or dibutyryl cyclic AMP. Of particular interest was the fact that cultures treated for the initial 24-hour culture period with ACTH maintained enhanced levels of secretion for several days in absence of hormone and had an enhanced response to ACTH later in the culture period. Such enhancement of secretion was not seen following early treatment with dibutyryl cyclic AMP. The fine structure of the ACTH-treated cells was consistent with increased steroidogenesis. They possessed more smooth-surfaced endoplasmic reticulum, larger mitochondrial crystal surfaces, and larger Golgi complexes than the cells in untreated cultures.