ULTRASTRUCTURE OF TESTICULAR GERMINATIVE ZONE AND SECONDARY SPERMATOGONIA IN NORMAL AND DESTALKED BRACHYURAN DECAPODS (CRUSTACEA)

  • 1 January 1977
    • journal article
    • research article
    • Vol. 66  (3) , 163-179
Abstract
Ultrastructural study of gonia of various species of male carbs [Rhithropanopeus harrisii, Sesarma reticulatum, Uca pugilator, Ocypode quadrata and Callinectes sapidus] shows that these cells are of 2 types: primary and secondary gonia, discriminated according to their location inside or outside the germinative islets, i.e., by the presence or absence of surrounding somatic tissue. The most characteristic feature of the primary spermatogonia is the extrusion of gonial material in the form of lamellar bodies or granules engulfed by the contiguous mesodermal cells; the latter degenerate when they are full of germ cell remnants. Poorly differentiated, the primary gonia have no great variety of cytoplasmic organelles. Two characteristic structures can be recognized in juxtanuclear position: nuage material (electron dense bodies more or less associated with gonia) and chromatoid bodies. Lipid droplets of unknown significance occur sometimes. Secondary spermatogonia divide synchronously although they are placed side by side without any connection such as cytoplasmic bridges. No ultrastructural modification was noticed among the 2 types of gonia in crabs deprived of eyestalks. Mesodermal tissue distributed between primary gonia probably has a double role: inhibition of the onset of gametogenesis (as in Amphipods) and prevention of gonial cytolysis by collection of altered elements. Disappearance of mesodermal cells after destalking experiments reveals that their maintenance is controlled by the eyestalk neurosecretion. An explanation related to the arrest of spermatogenesis in some destalked species is given.