Development of the Pars Intermedia Axis of the Hypophysis – Skin Melanocytes in Long-Tailed Macaques (Macaca Fascicularis)

The study investigated the development of the pars intermedia (PI) of the hypophysis and its role in melanogenesis in long-tailed macaques (Macaca fascicularis) during pre and postnatal periods. It involved 6 fetuses, 2 postnatal subjects, 1 infant, and 2 adults. The research found that the PI was initially dominated by acidophil cells, which were later replaced by basophil cells, including melanotropes and corticotropes. The distribution and density of ACTH-MSH immunoreactive cells in the PI correlated with the development of blood vessels and pigmentation patterns in the skin and hair follicles. The study concluded that the PI's development is closely linked to melanogenesis and pigmentation processes involving MSH and ACTH during different developmental stages.