Chloride‐type cells in the skin of the metamorphosing bonefish (Albula sp.) leptocephalus

Abstract

AbstractThe skin of metamorphosing bonefish (Albula sp.) larvae (leptocephali) was examined using both scanning (SEM) and transmission electron microscopy (TEM). SEM revealed that surface epithelial cells of larvae that were just entering the metamorphic phase possessed numerous ridges and that epithelial pores occurred randomly at cell junctions. The pores were very similar to those seen in gill tissue of adult marine teleost fishes where they have been shown to represent the apical crypts of chloride cells. TEM confirmed the presence of chloride‐type cells in the epidermis of early metamorphosing larvae that contained both numerous mitochondria and an extensive system of tubules that appeared to be derived from the plasma membrane. SEM of intermediate and advanced metamorphosing larvae showed that the ridged epithelial cells tended to be more disorganized and were possibly degenerating but that epithelial pores were still evident. TEM of the skin of early metamorphosing larvae also showed a loosely organized internal structure in some of the epithelial cells. The ultrastructure of the skin is discussed in terms of the morphological and physiological changes that take place during metamorphosis.