708 E. V. COWDEY 



nous sinus, and from the circle of Willis. The internal carotid arteries 

 give off very delicate branches, which run to the anterior lobe, and, 

 according to Mudd, to the posterior lobe also. Twigs from the circle 

 of Willis run downward with the pia mater which surrounds the in- 

 fundibulum, and supply the posterior lobe. Dandy and Goetsch, working 

 with the dog, have found that the pars intermedia also receives blood 

 from the circle of Willis, so that a collateral circulation obtains between 

 the anterior and posterior lobes, which, in their opinion, is "probably 

 sufficient to preserve the function of at least the adjoining portion of 

 either lobe, if its individual blood supply is cut off." Pending detailed 

 information, we must bear in mind that a similar condition may exist 

 also in man. 



There is a marked difference in the vascularity of the lobes, which 

 is well illustrated in Fig. 3. The pars anterior propria, in injected 

 specimens, looks like an almost solid mass of contorted blood vessels. 

 The pars tuberalis, when it is present, is said to be still more highly 

 vascular. The blood in the different parts of the hypophysis seems to 

 intermingle freely. In the sheep arterioles may be seen passing di- 

 rectly between the pars intermedia and the pars nervosa and between 

 the pars tuberalis and the tissue of the infundibular stalk. The capil- 

 laries in the anterior lobe are large and sinusoidal and come into very 

 intimate contact with the secreting cells. All the veins from both 

 lobes discharge into the circular sinus. 



Lymphatics. Lymphatics are often described in the hypophysis, 

 particularly in the anterior lobe, in connection with the discharge of 

 secretion ; but the exact method of drainage from the hypophysis remains 

 to be worked out. 



Innervation. Our knowledge of the nerve supply in man is very 

 scanty. Dandy, working again with the dog, finds that the nerves origi- 

 nate in the carotid sympathetic plexus and follow the arteries. He 

 considers them to be for the most part sensory, not vasomotor, as one 

 would naturally expect. The possibility of the existence of efferent 

 fibers, running to the gland, is indicated by Shamoff's claim that he has 

 been able to cause secretion of the hypophysis in the cat by stimulation 

 of the superior cervical ganglion of the sympathetic. 



Embryology 



Lobus Anterior. The anterior lobe is developed from an ectodermal 

 pouch, called the pouch of Rathke, which grows upward under the brain 

 from the stomodeal epithelium. In lower forms it is possible that there 

 m;iy be also an endodermal contribution from the fo<re gut, known 

 as tho pouch of Seessel. About the fourth week Rathke's pouch comes 



