THE PITUITARY BODY. 351 



THE PINEAL GLAND. 

 



This gland, also known as epiphysis cerebri, is situated in the 

 brain behind the posterior commissure and between the anterior 

 corpora quadrigemina. It is reddish gray in color, about 0.8 

 mm. long and 0.6 mm. wide, larger in childhood than in adult 

 life, and in the female than in the male. 



Structure. It is composed of connective tissue and follicles 

 lined with epithelium. In these follicles is a viscid fluid with 

 brain-sand^ acervulus cerebri, which consists of calcium phosphate 

 and carbonate, magnesium and ammonium phosphate, with some 

 organic matter. The pineal gland exists in the fetal brain in the 

 form of a hollow protrusion from the posterior part of the roof 

 of the interbrain. It is regarded by some as an atrophied third 

 eye. Schafer says that in the chameleon and some other reptiles 

 the pineal gland is better developed, and is connected with a 

 rudimentary median eye of invertebrate type, placed upon the 

 upper surface of the head. 



Its function is unknown. 



THE PITUITARY BODY. 



This body is also known as hypophysis cerebri. It is situated 

 on the sella Turcica of the sphenoid bone, is reddish gray in color, 

 and weighs from 4 dgm. to 8 dgm. 



Structure. It consists of two lobes, the anterior being the 

 larger. This lobe is developed as a hollow or tubular prolongation 

 of the epiblast of the buccal cavity, and consists of vesicles and 

 alveoli lined with columnar epithelium, which is in some places 

 ciliated. In the alveoli is sometimes found a colloid substance 

 similar to that in the thyroid, and around the alveoli are lymph- 

 atics and capillaries. Indeed, the resemblance in structure be- 

 tween the pituitary body and the thyroid has led to the supposi- 

 tion that physiologically they are related. 



The posterior lobe has a different origin from the anterior. It 

 is developed from the floor of the third ventricle, and in fetal life 

 communicates with this cavity through the infundibulum. It 

 consists in the adult principally of vascular connective tissue, con- 

 taining but few nervous elements. 



Function. The pituitary body has been repeatedly removed 

 from dogs and cats, death resulting within two weeks. The 

 symptoms following removal are (1) diminution of body-tem- 

 perature ; (2) loss of appetite and lassitude ; (3) muscular twitch- 

 ings, tremors, and spasms ; (4) dyspnea. Some of these symptoms 

 are improved by injections of extract of the pituitary body. It 

 will be remembered that some of these symptoms occurred after 

 ablation of the thyroid (p. 341), and it is stated that the pituitary 

 body becomes enlarged after thyroidectomy. Rogowitsch thinks 



