THE HYPOPHYSIS CEREBRI 



1275 



as also discovered, in the lymph issuing from the thymus, similar cells to those found in the 

 gland, and, like them, containing hemoglobin in the form of either granules or masses. From 

 these facts he arrives at the conclusion that the gland is one source of the colored blood corpuscles. 

 More recently Schaffer has observed actual nucleated red-blood corpuscles in the thymus. The 

 function of the thymus is obscure. It seems to furnish during the period of growth an internal 

 .secretion concerned with some phases of body metabolism, especially that of the sexual glands. 

 Vessels and Nerves. -The arteries supplying the thymus are derived from the internal 



ammary, and from the superior and inferior thyroids. The veins end in the left innominate 

 vein, and in the thyroid veins. The lymphatics are described on page 698. The nerves are 

 exceedingly minute; they are derived from the vagi and sympathetic. Branches from the descen- 

 dens hypoglossi and phrenic reach the investing capsule, but do not penetrate into the substance 

 of the gland. 





THE HYPOPHYSIS CEREBRI. 



The hypophysis (pituitary body) (Fig. 1180) is a small reddish-gray body, about 

 1 cm. in diameter, attached to the end of the infundibulum of the brain and resting 

 in the hypophyseal fossa. 



Ant. cerebral artery -.3 



Optic chiasma. 



Anterior lobe 

 of hypophysis 



^Jnfundibulum 

 --Circular sinus 



-' '.Cerebral peduncle 



Corpus mammiUare 

 Post, cerebral artery 

 Basilar artery 



Pons 



Posterior lobe 

 FIG. 1180. The hypophysis cerebri in position. Shown in sagittal section. 



Posterior lobe 



Optic chiasma 



3rd ventricle 



Extension of pars intermedia 

 into brain substance 



Process of pars intermedia 

 A nterior lob 

 Intraglandular cleft 



Pars intermedia, 

 FIG. 1181. Median sagittal section through the hypophysis of an adult monkey. Semidiagrammatic. (Herring.) 



The hypophysis consists of an anterior and a posterior lobe, which differ from 

 one another in their mode of development and in their structure (Fig. 1181). The 

 anterior lobe is the larger and is somewhat kidney-shaped, the concavity being 

 directed backward and embracing the posterior lobe. It consists of a pars anterior 



