Preliminary investigation on the submicroscopical structure of blood capillaries of the pineal body in the embryonic and adult domestic fowl.

The morphological changes of the blood network capillaries in the pineal gland of the domestic fowl during embryonic development and in the first post-hatching year have been analyzed. Our preliminary results indicate that the first intrinsic vessels, showing an immature aspect, appear among the epithelial vesicles on 7th-8th incubation day (i.d.), when the pinealoblasts are actively proliferating; then, they drastically increase in number (10th i.d.), but they begin to undergo significant maturative changes only on the 19th i.d., in parallel with the unfolding of the pinealocytes differentiation. Finally they reach the definitive set-up within the first post-hatching year, while the pineal is acquiring its full morphological and functional maturity.