Rat intermediate lobe cell groups in suspension culture: morphological and functional characteristics.

Intermediate lobe cells mechanically isolated from adult rat hypophyses were maintained in histiotypic suspension culture. The cells survived as long as six weeks. The proliferation of the connective tissue cells was limited, they did not overgrow the glandular cells. The fine structure of the parenchymal cells in the epithelial spherules of the early cultures was practically identical to that in the intact tissue. The morphological sign of exocytosed secretory material could also be found. In older cultures, cells with light and dark cytoplasm were present. The former gradually degenerated and disappeared, while the latter, forming trabecules, retained their intact fine structure. Immunoactive and bioactive ACTH was detected in the culture medium.