EPIPHYSIS CEREBRI 



583 



forms are abundant. In young sheep both types of cells are charac- 

 terized by pigment granules; in aged specimens the pigment is for 

 the most part present in the shape of extracellular clumps. Also in 

 these stages the connective tissue is relatively much more abundant, 



t, * 



FIG. 500. PHOTOMICROGRAPH OF A PERIPHERAL PORTION OF THE PINEAL BOOT 

 OF A 21 CM. SHKKP FETUS, SHOWING SEVERAL CYSTS AND VASCULAR TRABECUL.E, 

 AND AN ENORMOUS NUMBER OF INTRACELLULAR MELANIC GRANULES. X 250. 



and the interneuroglia cells rare. The intcrneuroglia cells are prob- 

 ably less highly differentiated neuroglia cells, both types originally 

 arising from ependyma. The interneuroglia cells also contain granules 

 and vacuoles of a lipoid nature, perhaps degenerative in significance; 

 no pheochrome granules are demonstrable. Involution begins about 

 the age of 7 years in man and <>nls about the age of puberty, though 

 regressive histo logical changes proceed throughout life. Adult corpora 

 pinealia present very variable historic pictures. 



