THE PITUITARY BODY 



(Pearl and Surface, 1915; Pearl, 1916; and Simpson, 1923). 

 It may be concluded that the feeding of the anterior pituitary 

 has no effect, or at most a very slight effect, on the produc- 

 tion of eggs by the hen. 



Although Dubowik (1930) found that homo-implants ap- 

 peared to increase egg-production by hens (or to cause a re- 

 sumption of egg-laying), other investigators obtained the op- 

 posite result by injecting crude extracts of the anterior lobe of 

 the ox. Walker (1925) showed that the intraperitoneal injec- 

 tion of a saline extract of the pars glandularis of the ox in- 

 hibited ovulation apparently by causing a follicular atresia 

 which interfered with the development of the ova. Noether 

 (1928, 1930-31) fully confirmed the experiments of Walker. 

 Inasmuch as the effect could be produced only by extracts of 

 the pars glandularis, Noether suggested that extracts could 

 be assayed in terms of their ability to inhibit ovulation. He 

 found that the minimal effective dose was equivalent to about 

 0.2 g. of fresh anterior lobe of the ox. According to Renoult 

 (1931), anterior-lobe extracts which cause luteinization of the 

 ovaries and growth in mammals inhibit ovulation in the hen, 

 whereas extracts causing more typical gonad stimulation in 

 mammals accelerate ovulation so that eggs without a shell 

 may be laid. 



Bates, Lahr, and Riddle (1935) stated that an extract of 

 the anterior pituitary, specifically affecting lactation in mam- 

 mals ("prolactin," see chap, vi), antagonized the follicle- 

 stimulating effects of other extracts on the fowl's ovary. 

 They also found (Riddle and others, 1935) that the extract, 

 "prolactin," seemed to provoke broody behavior particularly 

 in fowls actively laying eggs." 



In the immature fowl, Domm (1931, 1933) and Domm and 

 van Dyke (1932) showed that either homo-implants or a 

 gonadotropic extract of the sheep pituitary caused the fol- 



'" They stated that this effect was produced by extracts previously kept at ioo° C. 

 for one hour. 



[124] 



