Immunocytochemical Studies on the Cytodifferentiation of the Adenohypophysis of the Domestic Fowl

Abstract

The cytodifferentiation of the cephalic and caudal lobes of the chicken pituitary of different embryonic ages was studied by means of an immunocytochemical technique using antisera to avian and mammalian pituitary hormones. LH-immunoreactive (ir) cells occur first in 4-day embryos in the epithelium of the posterior process of Rathke's pouch, spread in the oral lobe in 6-day embryos and are distributed throughout the pars distalis in 8-day and older embryos. FSH-ir cells occur in the vental aspect of the caudal lobe in 8-day embryos and are distributed throughout the gland after 12-day. ACTH-ir cells occur first in the dorsal part of the cephalic lobe in 7-day embryos and are confined to the cephalic lobe thereafter. TSH-ir cells occur first in the ventral part of the cephalic lobe at 7-day and are confined to the cephalic lobe thereafter. GH-ir cells occur in the ventral portion of the caudal lobe in 8-day embryos, increase remarkably in the later embryonic period and occupy the caudal lobe thereafter. PRL-ir cells occur first in the cephalic lobe in 18-day embryos, and increase remarkably after hatching. The pars tuberalis contains numerous LH-ir cells since it is originated from the lateral lobe in 6-day embryos.