Blood Supply of the Hypophysis in the Dog

The blood supply of the hypophysis in the dog was examined by light microscopy and scanning electron microscopy. The anterior hypophyseal arteries converged toward the infundibular stalk, subdivided in the stalk, and entered the primary capillary net and capillary loops in the median eminence lying at the base of the third ventriculus. The portal vessels originated from the capillary net and loops, and were continuous with the capillary sinusoids in the pars distalis. Some of the anterior hypophyseal arteries supplied the pars distalis directly and were also continuous with capillary sinusoids. In its caudal pole, the pars nervosa received the posterior hypophyseal arteries, which formed a capillary plexus in the pars nervosa. The vessels of the pars nervosa broke up into a primary capillary net at the caudal areas in the median eminence. The vasculature in the dog hypophysis is compared with that in the rat.