REPRODUCTIVE ENDOCRINOLOGY IN BIRDS 



1103 



of tlu' younu;, testicular collapse docs not 

 seem to occur until the end of the breeding 

 season. An example of this is found in the 

 pheasant (Greeley and Meyer, 1953). 



The effects of other anterior pituitary hor- 

 mones on avian testes are difficult to eval- 

 uate because possible contamination by 

 gonadotrophins has not always been ex- 

 cluded. For example, adrenocorticotrophic 

 hormone (ACTH) injections to roosters and 

 capons were observed to be followed by an 

 increase in comb size of roosters but not of 

 capons. No atrophy similar to that in mam- 

 malian testes after ACTH administration 

 (Dulin, 1953) was observed. Dulin (1953) 

 assayed the ACTH preparation for gonado- 

 trophin but used an assay method (chick 

 testicular size as end point) which is not par- 

 ticularly sensitive for LH, the hormone 

 which stimulates androgen secretion. Dulin 

 explained the effect of ACTH by assuming 

 increased endogenous gonadotrophin secre- 

 tion by the ACTH-treated roosters. This as- 

 siunption was based on the increased pitui- 

 tary weights of the treated roosters. In view 

 of assay methods used, we feel that LH con- 

 tamination has not been excluded and that 

 further experimentation is required before 

 the described increase in comb size is as- 

 signed to ACTH per se. 



Discussion of the effects of nongonado- 

 trophic anterior pituitary hormones on gon- 

 ads does not seem fruitful in view of the 

 above mentioned possibility of gonado- 

 trophin contamination. 



£. The Pineal Body 



Of the several endocrine organs which 

 may affect testicular activity, the pineal 

 body has been a most controversial one. It 

 is fortunate that one of the experiments, in 

 which the classical endocrine approach of 

 al)lation and replacement therapy M'as used, 

 was carried out in the fowl. 



Shellabarger (1953) demonstrated that 

 ablation of the pineal body at an early age 

 caused an increase in testes and comb 

 weight, and a simultaneous increase in gon- 

 adotrophic potency of the pituitary. On the 

 other hand, injection of a pineal-body ex- 

 tract caused a decrease in testicular weight, 

 although a brain extract did not have this 

 effect. Pituitary potency was not affected 



by either treatment. Pineal extract injec- 

 tions into pinealectomized cockerels reduced 

 testicular size to that of nonoperated or 

 sham-operated controls. Miller (1955) ob- 

 served that the onset of sexual maturity in 

 two strains of chickens, differing widely in 

 the age at which sexual maturity is reached, 

 coincided with the change in the pineal body 

 from the follicular (active) to the lobular 

 (inactive) stage. In vitro studies by Mosz- 

 kowska (1958) established that the gonado- 

 trophic potency of chick pituitaries cultured 

 in vitro was higher w4ien the pituitaries were 

 cultured alone than wdien they were cultured 

 in the presence of pineal body. This evi- 

 dence strongly suggests that the pineal body 

 may act as an inhibitor of pituitary activity. 

 Moszkowska's experiments indicate that 

 this inhibition is probably direct. 



3. The Adrenal Gland 



The role of the adrenal in reproduction is 

 more difficult to evaluate in birds than in 

 mammals. Part of this difficulty is the result 

 of the intermingling of cortical and chromaf- 

 fin cells so that the effect of cortex and me- 

 dulla cannot be separated. The greater dif- 

 ficulty lies in the problem of complete 

 surgical removal of the adrenals and in the 

 high mortality after adrenalectomy (Parkes 

 and Selye, 1936; Biilbring, 1937, 1940; Ta- 

 ber, Salley and Knight, 1956). Leroy and 

 Benoit (1956) observed no mortality after 

 adrenalectomy of drakes, Anas platyrhyn- 

 chos, observations which do not agree with 

 those of other workers. Biilbring (1940) em- 

 phasized that in her work with drakes every 

 case of good survival was correlated with 

 the presence of adrenal tissue. Efforts to sus- 

 tain life of the adrenalectomized drakes, 

 A?ias platyrhynchosl , with desoxycorticos- 

 terone acetate (DCA) were successful only 

 as long as injections were given. A correla- 

 tion was found between the size of the testes 

 at the time of surgery and the dose of DCA 

 reciuired to keep adrenalectomized drakes 

 alive. This correlation was not a result of 

 higher androgen secretion by the larger tes- 

 tes, because testosterone injections did not 

 affect the amount of cortical extract re- 

 quired to keep castrated-adrenalectomized 

 clrakes alive (Biilbring, 1940). 



After adrenalectomy, roosters maintained 



