582 



THE DUCTLESS GLANDS ENDOCEIN GLANDS 



tion) upon the hypophysis transmitted through the third ventricle with 

 which both pineal and hypophysis are connected. Certain symptoms may 

 also be due to a blocking of the aqueduct, and to pressure upon the corpora 

 quadrigemina. A conservative estimate of all the evidence indicates very 

 meager, if any functional activity, probably never essential to life. The 

 practical absence of the pineal body in the opossum adds further support 

 to this conclusion; as also its occasional disappearance, except for a mere 

 shell, in apparently normal cats. Biedl (1910), however, arrives at the 

 conclusion that the pineal body is an organ of internal secretion with 

 metabolic significance limited to the young. Its general histological struc- 

 ture, and profuse vascularity, certainly suggest a glandular function. On 

 the basis of feeding experiments with bullocks' pineals on certain labora- 

 tory animals and mentally defective children, Dana and Berkeley (Med. 

 Bee., May, 1913) venture to suggest a relationship of pineal function in 

 the young to bodily nutrition, including the development of the genital 

 organs, the deposit of subcutaneous fat, general growth and mental prog- 

 ress. The pineal is a common seat of cysts and tumors, frequently glio- 

 mata. 



, 



Histologic Structure. The epiphysis cerebri is divided imper- 

 fectly into lobes by trabeculse of fibro- 



9 M *+ ' ^ elastic connective tissue provided by the 



pia mater capsule. These support the 

 larger blood-vessels. The finer trabeculse 

 shade into the fundamental reticular tis- 

 sue which supports the parenchyma and 

 the capillaries. The larger vessels are 

 surrounded by considerable spaces, per- 

 haps lymphatics. The parenchyma is 

 aggregated into uncertain follicular 

 masses and consists of two distinct types 

 of cells: neuroglia and interneuroglia 

 (secretory cells?). The abundant neu- 

 roglia fibers appear to blend intimately 

 with the connective tissue framework of 

 the structure. The interneuroglia cells 

 are oval and polygonal, with a vesicular 

 nucleus, and apparently lacking a cell 

 membrane. The neuroglia cells are 

 fusiform or stellate, with denser, more 

 deeply staining nuclei, and glia fibers in the cytoplasm. Transition 



I 



FIG. 499. CELLS FROM THE PI- 

 NEAL BODY OF A 11 CM. SHEEP 



FETUS. 



a, two neuroglia and one inter- 

 r2uroglia cell; b, various forms and 

 sizes of intracellular melanic gran- 

 ules. X 1500. 



