THE PITUITARY BODY 



one invertebrate, the snail. Other morphological characteris- 

 tics which have been described in these nuclei are multinu- 

 clear cells, endocellular capillaries, and degeneration and dis- 

 integration of the cells. All these observations seem to place 

 the neurones of the supraoptic and paraventricular (and per- 

 haps the tubero-mammillary) nuclei in a category different 

 from that of other cells of the central nervous system, al- 

 though Peters found colloid inclusions in cells of certain nu- 

 clei of the medulla oblongata. 



The evidence that such cells secrete colloid and are to be 

 considered a "diencephalic gland" is morphological and does 

 not deserve acceptance at this time. The "secretory activity" 

 of these cells appears to be slight in childhood; it is not other- 

 wise correlated with age and is not altered as a result of 

 nervous or endocrine diseases. 



THE PARS INTERMEDIA, THE PARS NEURALIS 

 AND THE PARS TUBERALIS 



It has again been emphasized that the pars intermedia of 

 man and the anthropoid apes is a structure so rudimentary in 

 appearance that it appears to have no important function 

 (Berblinger and Burgdorf, 1935; Plaut, 1936; and Scriba, 

 1936). Frequently, also, the human pituitary contains no re- 

 sidual cleft of Rathke's pouch. In the pituitary of the por- 

 poise^ and the whale,^ the pars glandularis is completely 

 separated from the pars neuralis by a leptomeningeal-dural 

 fold. The embryologic development of the organ in the por- 

 poise and whale is therefore apparently different from that in 

 other mammals. No pars intermedia can be recognized in the 

 cetacean pituitary.^ According to Benjamin (1935), the de- 

 posits of pigment in the pars intermedia and in the pars 

 tuberalis of wild and hooded rats — but not present in pure 



5 Tursiops truncatus. 



* Balaenoptera physalus, B. sibbaldi, and Physeter megalocephalus (see Gelling, 

 1935; and Wlslockl and Gelling, 1936). 



' Whether or not a pars intermedia can be identified in the bird's pituitary is still 

 undecided (see the discussion of Wislocki and Gelling). 



f 10] 



