ULTRASTRUCTURE OF THE GLANDULAR EPIDERMIS ON THE FINS OF MALE ESTUARINE TRIPLEFINS FORSTERYGION NIGRIPENNE

Male estuarine triplefins Forsterygion niguipenne develop enlarged fin tips during the breeding season. Using light microscopy and scanning and transmission electron microscopy the fins of males and females wer e compared. Tall columnar cells proliferated in the fin epidermis of m ales but were absent in females. The columnar cells were packed with p roteinaceous granules that were bound by a double membrane. Three stag es of development of columnar cells could be distinguished; the most m ature expanded and ruptured to release its content. The function of th e glandular epidermis is unknown but behavioural observations suggeste d that the secretion was applied to the egg mass and thus may protect it from infection. (C) 1996 The Fisheries Society of the British Isles .