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SUMMARY Primary tissue cultures of adrenal cells were prepared from foetal rat adrenals. The effect of cyclic AMP (75 μmol/l) on the morphology and steroid synthetic activity of the cortical cells was examined in order to determine whether cyclic AMP mimics the effects induced by adrenocorticotrophin (ACTH); namely transformation to the differentiated cell type and increase in steroid synthetic activity. Cyclic AMP was found to induce some, but not all, of the changes normally induced by ACTH. In particular, the mitochondria in the cortical cells developed vesicular cristae and there was a proliferation of the smooth endoplasmic reticulum. These two organelles are the principle sites of enzymes involved in steroid synthesis and the ultrastructural transformation was accompanied by an increase in the steroidogenic activity of the cells. However, clear differences in the ultrastructure of the cyclic AMP- and ACTH-treated cells were noted. The effects of cyclic AMP on the ultrastructure of cortical and fibroblastic cells present in the adrenal cultures were found to be dependent upon the cell type.

The morphological and biochemical evidence supporting a relationship between structure and function has been examined for those endocrine cells involved in steroid biosynthesis. Recent evidence indicating that this relationship may not be a simple one has been presented and the usefulness of a morphological approach in assessing the functional activity of cells is discussed.

SUMMARY The effects of human pituitary extracts upon steroid biosynthesis by pieces of human adrenal tissue incubated in Krebs—Ringer bicarbonate buffer have been studied. Experiments with both adult and foetal adrenal tissue have been carried out. Radioactive precursor (either [7-3H]pregnenolone or [4-14C] progesterone) was added to each incubation vessel and the synthesis of radioactively labelled products was estimated by reverse isotope dilution. Individual steroids were characterized by paper and thin-layer chromatography; the radiochemical purity of cortisol, androstenedione, dehydroepiandrostenedione (DHA) and DHA sulphate was established following derivative formation. There was no consistent effect of the pituitary preparations upon the biosynthesis of cortisol, DHA or DHA sulphate, nor upon the ratio of cortisol to the combined production of DHA and DHA sulphate. However, the production of androstenedione from both [7-3H]pregnenolone and [4-14C]progesterone was significantly increased in the presence of pituitary and gonadotrophic preparations.

SUMMARY Human adrenal tissue was sliced and incubated with 25 μc [7α-3H]-pregnenolone. The percentage conversion of radioactive precursor to dehydroepiandrosterone (DHA), DHA sulphate, androstenedione, 11β-hydroxyandrostenedione, cortisol and 11-deoxycortisol was estimated by the reverse isotope dilution technique. Incubations of both adult and foetal adrenal slices gave reproducible results. The duration of the incubation period was an important factor affecting the pattern of radioactive steroids synthesized, the adult adrenal pattern being dissimilar to that of the foetal adrenal. A direct proportional relationship between the weight of the incubated tissue and the biosynthesis of cortisol from exogenous [7α-3H]-pregnenolone was not established. The production of DHA sulphate relative to free DHA increased markedly from 12 to 27 weeks gestation. When incubated for 2 hr. the combined production of DHA and DHA sulphate relative to cortisol and androstenedione decreased with gestational age. There was evidence for considerable 3β-hydroxysteroid dehydrogenase activity in foetal adrenals at 12 to 27 weeks gestation.

SUMMARY Adrenals from foetuses of 13 to 27 weeks gestation were sliced and incubated with 5 μC of [4-14C]progesterone for 2 hr. The biosynthesis of cortisol, 11-deoxycortisol, androstenedione and 11β-hydroxyandrostenedione was estimated by reverse isotope dilution. Cortisol was the major product identified and the production of both cortisol and 11β-hydroxyandrostenedione increased with gestational age in approximate proportion to the increasing adrenal weight. The ratio of (cortisol plus 11-deoxycortisol) to (androstenedione plus 11β-hydroxyandrostenedione) was constant at 13, 16 and 27 weeks gestation. The production of cortisol and androstenedione from progesterone and from pregnenolone by adrenal tissue from a 27-week-old foetus is compared.