Spermatozoa of the giant octopus of the North Pacific Octopus dofleini martini

Abstract

Spermatozoa of the giant octopus, as obtained from ruptured metre-long spermatophores, are only feebly motile. The total length of a spermatozoon is 1/2 mm, most of it due to the tail. The sperm-head, slim and oblong, is composed of a highly condensed nucleus and a cork-screw shaped acrosome. A striking feature, which distinguishes octopus spermatozoa from those of mammals, is the presence of a large amount of glycogen, concentrated mainly around the sperm-head. This, together with the occurrence of high phosphorylase and phosphoghlcomutase activity, indicates that glycogenolysis represents a pathway of carbohydrate metabolism in octopus spermatozoa. Both glucose-6-phosphate isomerase and glucose-6-phosphate dehydrogenase were demonstrated in extracts of prepared sperm- homogenates, which suggests that octopus spermatozoa may be capable of metabolizing glucose-6-phosphate along the oxidative as well as the glycolytic pathway.