Abstract
Chromophobes isolated by the original method from the rat anterior pituitaries morphologically differentiated into acidophils when cultured in a chemically defined medium, NCTC-109, supplemented with various amounts of CRF (0.15 to 15μg/2ml) and colchicine. An electrophoresis and a paper chromatography revealed that ACTH was a main hormone produced by the cells maintained in the supplemented medium for as long as 12 days. The addition of larger amounts of CRF shortened a duration to reach to a certain maximal level of ACTH concentration in the cells, and this maximal level was equivalent in the cases of the variable amounts of CRF. A maximal release of the ACTH from the cells into the medium took place always 3 days after reaching to a maximal concentration of ACTH in the cells. The chromophobes produced α-MSH only in an earlier phase of differentiation without discharging it into the medium. The intracellular granules isolated from the cells kept in the control medium were equally 100 to 150 mp in diameter and regarded as the common storage carriers of six trophic hormones because they showed commonly all their low activities. Three different granules were successfully isolated from the cells differentiating in the CRF-medium from the chromophobes into the acidophils with negligible cross-contaminations. They were small (100 to 200mμ in diameter), large (300 to 450 mμ) and huge and irregularly shaped granules (450 to 1000 mμ) respectively. All the granules were confirmed by bio-and immuno-assays to contain ACTH activity alone regardless of their dimension.
