Fine structure of spermatogenesis in the spider crab Lissa chiragra (Fabricius, 1775) (Eubrachyura, Epialtidae)

This article uses the male spider crab Lissa chiragra, collected from Ras el Tin beach on the Mediterranean Sea at Alexandria, Egypt, between January and December 2017, as a model for a descriptive study of the functional morphology of the different structures of spermatogenesis with the aid of the transmission electron microscope. This study divides the seminiferous tubule into three zones, i.e., the germinal, transformation, and evacuation zone. The transformation or maturation zone occupies the central area. The evacuation zone lies at a pole opposite to the germinal zone. The anterior vas deferens is a tube where the formation of the spermatophore occurs by means of secretions from the epithelium. The ejaculatory duct is located between the muscles of the coxae of the fifth walking legs. This study concluded that the complex acrosome vesicle is formed during spermiogenesis and the cytoplasm includes the membrane system, constituted by the endoplasmic reticulum, Golgi apparatus, and vesicles associated with microtubules, and a few mitochondria. The Golgi apparatus is developed and is organized progressively to produce various vesicles. The cytoplasm forms a ring at the base of the nuclear extensions. The merger of the plasma and nuclear membranes, results in a pentalaminar membranous structure in some regions of the cell surface.