PROLACTIN (PRL)-CODING MESSENGER-RNA IN TYPHLONECTES COMPRESSICAUDUS,A VIVIPAROUS GYMNOPHIONAN AMPHIBIAN - AN IN-SITU HYBRIDIZATION STUDY

A study of prolactin-mRNA expression in the hypophysis of male and fem ale Typhlonectes compressicaudus was carried out, using a quantitative in situ hybridization technique. In both males and females, an in cre ase in the number of cells showing prolactin-like expression was obser ved at the beginning of the dry season. In the middle of the season, t his number decreased. In pregnant females, mRNA expression remained co nstant during the first stages of gestation but, in the final stages, when embryos reached their maximum development, mRNA. expression incre ased. In males and in sexually inactive females, prolactin-mRNA expres sion was the same throughout the year. We conclude that the activity o f cells expressing prolactin could be related to hydromineral regulati on and, in females, to the gestation process.