303 



NORMAL HISTOLOGY. 



THE PINEAL BODY. 



The pineal body, also called the epiphysis and the conarium, is a cone- 

 shaped organ, from 8-10 mm. in length, attached to the posterior extremity 

 of the roof of the third ventricle. 



Retinal 



Lenticular area 



Connective 

 tissue septa 



FIG. 354. Section of pineal body, showing general structure and calcareous concretions. X 130. 



As seen in sections of the adult human organ, its structure includes a 

 reticular framework of vascular connective tissue trabeculae, the meshes of 



which are filled with round- 

 ed or elongated epithelial 

 cells, which often contain 

 brownish pigment. With 

 the exception of a few 

 nerve-fibres in the anterior 

 part, probably sympathetic 

 in origin and destined for 

 the walls of the blood-ves- 

 sels, and a dense network 

 of neuroglia-fibres in the 

 under part, the pineal 

 body contains no elements 

 of a nervous character, 

 nerve-cells being absent. 

 Very commonly the adult 

 organ encloses a variable 

 number of concretions, 

 called brain-sand or acer- 

 vulus cerebri, which consist of laminated masses composed of calcium car- 

 bonate and phosphate, mingled with organic material. They may be of 

 microscopic dimensions, or reach the size of a millet seed, and by aggre- 

 gation assume a mammillated form. 



F'G-355- Sagittal section of pineal organ of lizard embryo. X 175- 



