Immunohistochemical identification and morphometric study of ACTH cells of mink (Mustela vison) during growth and different stages of sexual activity in the adult.

The morphological characteristics and changes in the cellular area and volume density of ACTH cells have been examined in the mink from the first half of the suckling period to adulthood and in the adult mink at different stages of the sexual cycle. ACTH cells were identified immunohistochemically (avidin-biotin complex) and applied over semithin sections. Unlike in suckling and prepubertal mink, there was a clear topographic relation between adenohypophysial follicles and ACTH cells in pubertal and adult animals. The ACTH cells presented a morphological pleomorphism, appearing from oval or round to stellate or angular. The morphometric study demonstrated that the cellular area and volume density of ACTH cells varied during growth and in adult mink there were sexual variations. Gonadal steroids may influence ACTH cells especially in females, in which there were variations before and after puberty. The heterogeneity in size, shape, secretion, and storage parameters of the ACTH cells could explain the presence, in some of the groups studied, of an increased or decreased cellular area, while the volume density remained unchanged.