This study was carried out on pituitary glands collected from buffalo embryos and fetuses with a crown vertebral rump length (CVRL) ranging from l.5 to 95 cm. The specimens were immediately immer-sed in the fixatives at least 3 days and paraffin embedded for routine histological work. The primordia of the pars intermedia (PI) appeared at 1.5 cm CVRL as group of undiffere-ntiated mesenchymal cellular band. This band was completely enclosing the pars nervosa (PN) at 3.2 cm CVRL. It appeared thick ventrally around the bottom of the PN. It was separated from the pars distalis (PD) via the hypophyseal cleft and from the neural lobe via thick reticular connective tissue fibers. These cells were differentiated to chromophils and chromophobes at 24 cm CVRL. The chromophils were exclusively basophils. Melanotrophs (MSH-cells) began to appear as polyhedral cells; seen scattered among the follicular cells at 35 cm CVRL. Adrenocorticotrophs (ACTH-cells) first appeared at 75 cm CVRL. The numbers of MSH- and ACTH-cells increased toward the full term age. In conclusion, this numerical increase might prepare the foetal adrenals to face the stresses during and after parturition; and the foetal skin to protect itself (by melanin) from the solar insults. |
