Morphological and physiological factors involved in the contractility of the spermatic cord and ductus deferens of the opossum (Didelphis albiventris)

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Abstract
The opossum spermatic cord is characterized by a thick skeletal muscle coat, provided by the extensive development of the cremasteric muscle. Acetylcholine induced a powerful contraction of the spermatic cord placed in an organ bath containing Heller''s solution. This contraction was blocked by curare but not completely by atropine as is usual for skeletal muscle. The ductus deferens did not respond to acetylcholine or catecholamines under the same conditions. Specific histochemical methods for both catecholamines and acetylcholinesterases revealed that the ductus deferens musculature, composed mainly of circular fibers, is richly innervated by adrenergic and presumed cholinergic nerve fibers. The lack of responsiveness to the neurotransmitters could be explained by the absence of longitudinally arranged muscle. In the opossum, the cremaster could participate in the mechanism of sperm transport.