The fine structural organization of the sea nettle fishing tentacle

Abstract

Abstract The fishing tentacle of the sea nettle ( Chrysaora quinquecirrha ) has four basic layers: an outermost epithelial layer, a muscle cell layer, a core of mesoglea and an innermost epithelial layer. The outermost epithelium contains three different cell types: (1) supporting cells, (2) nematocytes and (3) mucous cells. Apical cellular processes of smooth muscle fibers extend into the outermost epithelial layer whereas basal processes penetrate the mesoglea. The mesoglea contains randomly oriented fibrils (60–70 Å in diameter). Inner epithelial cells vary in morphology. Some cells contain mostly phagocytotic vacuoles while other cells have an abundance of rough surfaced endoplasmic reticulum.