Tail height, a prolactin-dependent ambisexual character in the newt (triturus cristatus carnifex Laur.)

Abstract

In castrated as well as in castrated and thyroidectomized Triturus cristatus carnifex adults from both sexes, prolactin administration alone (100 IU per newt), unlike LH or TSH, was seen to promote the increase in tail height, which is a seasonal gonadal hormones-independent ambisexual character. The same effects were seen to be exerted in the summer, or in aestivating normal newts by exogenous prolactin, or by treatments enhancing endogenous prolactin production, such as a drop in temperature and ectopic pituitary autografts. The naturally occurring seasonal variations in tail height parallel the circumannual prolactin level variations and water drive. Consistent changes are entailed by prolactin in both the fin connective axis (swelling and pigment redistribution in chromatophores) and the epidermis (acceleration of the mitotic rhythm and slowing down of keratinization processes). The present results lead us to conclude that the seasonal ambisexual character here investigated, the height of the tail, is prolactin dependent. The parallelism between water drive and tail height variations is stressed. © 1970.