206 ENDOCRINE GLANDS 



PATHOLOGICAL ANATOMY. 



The chief lesion consists in a marked internal hydro- 

 cephalus, dilatation of the third and lateral ventricles, 

 compression of the floor of the third ventricle (even the 

 pituitary) and the cerebral hemispheres. 



It is usually inside of the third ventricle that the pineal 

 tumor is found. It is sometimes the size of a small nut 

 or a small apple. More rarely it develops posteriorly 

 towards the cerebellum. The tubercula quadragemina 

 are then compressed or destroyed; the veins of Galen are 

 dilated and filled with blood. The aqueduct of Sylvius is 

 compressed or obliterated. Some large tumors destroy 

 the roof of the aqueduct, the posterior part of the corpus 

 callosum and the posterior portion of the optic layers. 



The histological structure of these tumors is variable. 

 Those most often met with are cysts, then teratoma. 

 Glioma, sarcoma and carcinoma. Mixed tumors have also 

 been found and occasionally tubercles. 



PATHOGENESIS. 



We still have much to learn about this gland, both 

 from a histological and physiological point of view. 



Histologists do not agree on its structure. Some only 

 recognize nerve cells, others derivatives of nerve and 

 glandular cells, the latter characterized by large nuclei, 

 sometimes dark, sometimes light, and with a granular or 

 vascular protoplasma. 



One fact seems to be established; that is, that the gland 

 only appears active in childhood, and from the age of 7 on 

 it seems to involute, which fact manifests itself by cysts 

 and calcarious deposits. From these histological modi- 

 fications it can be understood why tumors of the pineal 

 gland only develop in infancy. 



Marburg thinks that he has been able to find in the 

 somaric disturbances of pineal tumors various disturb- 



