Mammotrope heterogeneity in the pituitary gland of European ferret, M ustela putorius Juro: An immunoelectron-microscopic study.

ABSTRACT

Employing the superimposition technique of electron-microscopic immunocytochemistry ultrastructural heterogeneity of the mammοtropes in the pituitary gland of the European ferret, Mustela putorius furo, was studied. On the basis of the size of their secretory granules, the mammotropes were classified into three subtypes, type-I, type-II and type-Ill, which may correspond to different developmental or physiological states of a single cell type. Simultaneous study of mammotropes and somatotropes in several pairs of serial semithin sections demonstrated the occasional occurrence of bihormonal somatomammotropes/ mammosomatotropes which may represent a transitional stage of the progenitor stem-somatotrope during its differentiation into mammotrope; alternatively it may be a functional intermediate during the cross-transformation of somatotrope into mammotrope or vice versa.