THE PITUITARY BODY 



the effect of pituitary extracts particularly on the erythro- 

 phores of other fishes has been studied. 



At the time of spawning there occur changes in the pig- 

 mentation of fishes such as the stickleback {Gastrosteus 

 aculeatus)^ the Bitterling [Rhodeus amarus)^ and the small 

 carplike Phoxinus laevis. The most prominent alteration con- 

 sists of the development of a brilliant red color in the ventral 

 part of the body, especially about the fins. This "wedding 

 dress" is much more prominent in the male and may persist 

 for more than 2 months. According to Osterhage (1932), the 

 pigmentary change is due principally to the formation of 

 new pigment-containing cells as well as to the deposition of 

 new pigment in old cells. Most of the studies on the dis- 

 persion of the erythrosomes ("expansion" of erythrophores) 

 have been made in P. laevis in which the response appears to 

 be more delicate than in other fishes. However, it appears 

 that extracts of the posterior lobe or pars intermedia do not 

 cause changes in the pigmentation so that the appearance is 

 like that of a typical "wedding dress." The development of 

 the latter also probably depends in part upon the gonads. 



The first experiments in P. laevis were performed by 

 Abolin (1925), He found that the injection of a posterior-lobe 

 extract caused a dispersion of the pigment granules in all 

 the important chromatophores (melanophores, xanthophores, 

 and erythrophores). However, the melanophores did not be- 

 have like the other chromatophores. The response of the 

 melanophores to posterior-lobe extract appeared earlier and 

 was of shorter duration. Also, the melanophores, unlike the 

 other chromatophores, seemed to be controlled partly by the 

 sympathetic nervous system (see also Giersberg, 1931, and 

 Smith, 1931). Others have observed that posterior-lobe or 

 pars intermedia extract causes a dispersion of the melano- 

 somes in Phoxinus (Osterhage, 1932, and Zondek and Krohn, 

 1932; on the other hand, Collin and Drouet, 1933, using 

 "Pitressin" observed the opposite effect). Generally, how- 



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