Fig. 43-12. The hypophysis cerebri. A and B illustrate the terminology. C shows the blood supply. Arteries in the hypo. physial stalk break up into capillary loops, which drain into hypophysial portal vessels. These, on reaching the pars distalis, drain into sinusoids, which enter the venous sinuses around the gland. D illustrates schematically the hypothalamohypophysial tract. Click for high resolution image.