The gonad wall of the sea urchin consists of an outer epithelium,
the outer surface of which is bathed in the perivisceral fluid,
a middle layer of conspicuous bands of smooth muscles and
connective tissue and an inner layer of developing gametes with
nutritive cells (Vivek Raja, 1980). The release of gametes, in
nature is effected by the contraction of the muscular bands which
is directly under the stimulatory effect of the radial nerve hormone
(Cochran and Engelmann, 1972). The gamete discharge may
be induced by acetylcholine, potassium chloride or by electrical
stimulation