HYPOPHYSEAL MORPHOLOGY 



165 



from tlie pars intermedia tissue in the inter- 

 mediate lobe, and the neurohypophyseal 

 hormones, oxytocin and vasopressin. 



In whales (Wislocki and Geiling, 1936) 

 and porpoises (Wislocki, 1929) and in the 

 armadillo (Oldham, 1938), manatee (Old- 

 ham, McCleery and Geiling, 1938) , elephant 

 (Wislocki, 1939), pangolin (Herlant, 



1954a), beaver (Kelsey, Sorensen, Hagen 

 and Clausen, 1957) , and the whole class of 

 birds (DeLawder, Tarr and Geiling, 1934; 

 Rahn and Painter, 1941), the cavity of 

 Rathke's pouch is obliterated during devel- 

 opment so that there is no hypophyseal cleft 

 (Fig. 3.3). Moreover, in all these animals 

 there is no adherence of the adenolobe to the 



Figs. 3.2, 3.3, 3.4, and 3.5. Diagrams of sagittal sections of the hypophyses of rat, cat, ox, 

 and blue whale showing some of the variations encountered. The left side of the diagram is 

 anterior, the right, posterior. (Modified from B. Romeis, in Handbnch der mikroskopischen 

 Anatomie des Menschen, Vol. 6, Part 3, JuHus Springer, Berlin, 1940.) 



Fig. 3.2. The rat hypophysis is of the conventional form but rotated to bring the anterior 

 lobe below and the posterior lobe above the axis of the gland. 



Fig. 3.3. The hypophysis of the blue whale. In this form the adenolobe is not divided by a 

 cleft and is not in close contact with the neural lobe, being separated from it by a fold of con- 

 nective tissue (D) continuous with the dura. The adenolobe is filled with pars distalis tissue 

 which combines the functions of the pars anterior and the pars intermedia of the more usual 

 mammalian form. In these respects the hypophyses of birds, porpoises, the armadillo, the ele- 

 phant, the pangolin, and the beaver resemble the hypophysis of the whale. 



Fig. 3.4. In the hypophysis of the ox the pars intermedia is less extensive than the inter- 

 mediate lobe and the remainder of the intermediate lobe is occupied by typical pars anterior 

 tissue. The segment of pars anterior tissue which is in the intermediate lobe and is separated 

 from the bulk of the pars anterior by the hypophyseal cleft is known as the cone of Wulzen 

 (Wulzen, 1914). 



Fig. 3.5. In the cat hypophysis the neural lobe is deeply embedded in the adenolobe. Par? 

 intermedia tissue occupies the entire intermediate lobe and extends into the anterior IoIk- 

 particularly in the caudal region. 



