Gill-derived glands in species of Astyanax (Teleostei: Characidae)

Abstract

The presence of a gill-derived gland is herein reported for the first time in males of species of Astyanax and related genera; they are described through histological cuts and SEM. The gill-derived glands described for the Characidae, when fully developed, present a similar structure in different species. The main external feature of gill-derived glands is the fusion of anteriormost gill filaments on the ventral branch of first gill arch. This fusion is caused by squamous stratified epithelial tissue that covers adjacent filaments, forming a series of chambers. In the region where the gill-derived gland develops, the secondary lamellae of the gill filaments are much reduced or completely atrophied being characterized by the presence of glandular cells forming nests.