lOIO HANDBOOK OF PHYSIOLOGY ^-^ NEUROPHYSIOLOGY II 



FIG. I. Diagram of a sagittal section through the pituitary 

 gland (of a rabbit) illustrating the general pattern of blood 

 supply. The anterior and posterior hypophysial arteries, A and 

 B, are derived from the internal carotid arteries. The arterial 

 twigs, C, to the pars tuberalis plexus (which in turn supplies 

 the primary plexus of the portal vessels) are derived from the 

 internal carotid and posterior communicating arteries. The 

 venous drainage, X), passes to surrounding venous sinuses in the 

 dura mater or in the basisphenoid bone. [From Harris (156).] 



of this technique. The position may be summarized, 

 "The pars distalis of the pituitary may, in general 

 terms, be described as a gland under nervous control 

 but lacking a nerve supply" (152) and, "It is agreed 

 that the anterior pituitary is devoid of secretory 

 nerve fibers and that therefore the mechanisms of 

 secretion must be attributed to humoral factors that 

 reach the gland through its blood supply" (214). 



The blood of the pars distalis may be likened to 

 that of the liver in that the gland possesses a systeinic 

 arterial supply, a portal blood supply and a systemic 

 venous drainage (fig. i). The systemic arterial supply 

 appears to be variable in pattern in different forms 

 (see 156). In some animals, such as the rabbit, a 

 definite arterial twig derived from the internal carotid 

 may be traced into the anterior lobe (150) while in 

 other forms, such as the bird (357), rat (205) and 

 human (236, 364), the systemic supply seems to be 

 scanty. However, interruption of the portal vessels 

 has been found to result in only minor degrees of 

 atrophy of the gland (see below) so that it is safe to 

 conclude that a functional systemic supply exists 

 whether it is in the form of capsular capillaries or 

 small arterioles. 



The venous drainage of the anterior and posterior 

 lobes of the pituitary is by means of short wide veins 

 draining into surrounding venous sinuses in the dura 

 or in the sphenoid bone. A knowledge of the anatoiny 

 of the pituitary venous system, from the gland to the 

 jugular veins, is likely to be of great importance in 



Fig. -2. Photograph of the anterior aspect of the pituitary 

 stalk in man. AT, artery of the trabecula; HS, hypophysial 

 stalk; PD, pars distalis. The blood vessels have been injected 

 with neoprene latex. Note the prominent trunks of the portal 

 vessels on the anterior surface of the stalk. These \essels trans- 

 port blood from the primary plexus, situated in the median 

 eminence of the tuber cinereum above, to the sinusoids of the 

 pars distalis below. (The latter sinusoids have been partly dis- 

 sected in the substance of the gland.) [From Xuereb et al. 

 (365)-] 



future years (in attempts to collect pituitary venous 

 blood for direct assay of pituitary trophic hormones) 

 but so far seems to have received little study. In 

 general pattern it would appear to be very \'ariable 

 in different forms. 



The hypophysial portal blood supply was first 

 noted by Professor F. I. Rainer of Bucarest and first 

 described in detail by Popa & Fielding (266, 267). 

 These workers described their findings in the human, 

 and were soon confirmed by Wislocki & King (361) 

 and Wislocki (358, 359) and later by Green & Harris 

 (126) and Wingstrand (357) in a variety of animals. 

 This vascular supply of the monkey (359) and man 

 (236, 365) has recently been studied in detail and 

 beautiful reproductions and microphotographs have 



