Prolactin (PRL)-coding mRNA in Typhlonectes compressicaudus,a viviparous gymnophionan amphibian: an in situ hybridization study

A study of prolactin-mRNA expression in the hypophysis of male and female Typhlonectes compressicaudus was carried out, using a quantitative in situ hybridization technique. In both males and females, an increase in the number of cells showing prolactin-like expression was observed at the beginning of the dry season. In the middle of the season, this number decreased. In pregnant females, mRNA expression remained constant during the first stages of gestation but, in the final stages, when embryos reached their maximum development, mRNA expression increased. In males and in sexually inactive females, prolactin-mRNA expression was the same throughout the year. We conclude that the activity of cells expressing prolactin could be related to hydromineral regulation and, in females, to the gestation process.