Studies on ulcerative dermal necrosis of salmonids

Abstract

The skin of the head of adult Atlantic salmon S. solar L. was examined by light and electron microscopy. The general structure resembled that of most other vertebrates, but in common with other fish, the melanocytes were restricted to the papillary layer of the dermis. The mucus secreting cells were shown to elaborate a series of separate membrane bound vesicles of secretion. The basement‐membrane was complex, with a system of primary, and secondary micro‐papillae showing close adherence to the bases of the epithelial cells, which were modified to form a thick, electron dense basal plasma membrane. No evidence to suggest a reason for the localization of the early lesions of ulcerative dermal necrosis to specific areas of the epithelium of the head was adduced.