Developmental immunohistology of melanotrophs in Xenopus laevis tadpoles.

The adenohypophysial primordium of Xenopus laevis tadpoles at stages 33/34 to 46 (Nieuwkoop and Faber, 1956) were examined immuno-histologically for α-MSH, β-MSH and ACTH. β-MSH was demonstrated from stage 37/38 onwards, and α-MSH from stage 39. No signs of ACTH production were detected. α-MSH and β-MSH occurred in the same cells. No differences were found in the intensity of immunofluorescence between tadpoles which were kept on a black and a white background. The present study lends no support to the hypothesis concerning the derivation of α-MSH from ACTH. The observations made suggest that the morphological formation of the pars intermedia is accomplished during stages 37/38 to 39. [ABSTRACT FROM AUTHOR]