Pigmentation changes in tadpoles of Rana pipiens following centrifugation during the early gastrula

✍ Scribed by H. W. Beams; R. L. King

• Publisher: John Wiley and Sons
• Year: 1938
• Tongue: English
• Weight: 657 KB
• Volume: 63
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1050630304

✦ Synopsis

Abstract

Centrifuging the eggs of Rana pipiens in the early gastrula stage prevents the formation of the hypophysis in some of the tadpoles. The absence of the melanophorotropic hormone normally secreted by the hypophysis seems to be responsible for the contraction of the pigment cells. In addition, there are actually fewer pigment cells present in both the dermal and epidermal layers of the light tadpoles than there are in the controls. The paleness, therefore, of the tadpoles seems to be due to both a contraction of the pigment cells present and to an actual reduction in their number. The failure of the hypophysis to develop was brought about by centrifuging at an earlier stage in development of the embryo than in previous extirpation studies. The effects produced by centrifuging that are responsible for the failure of the hypophysis to develop are unknown. However, it is suggested that interference in some way with the presumptive hypophysis‐forming tissue has resulted in an inactivation of its inductive potencies.