Ultrastructural study of the spermatozoon of Nephrops norvegicus (Crustacea, Decapoda) with special reference to the cytoskeleton

Abstract

The present study reviews the morphology of the spermatozoon of the Norway lobster Nephrops norvegicus. Male were collected at Western Mediterranean, Barcelona, Catalonia. Testes and reproductive tracts fragments were processed for transmission and scanning electron microscopy. The aflagellate spermatozoon of N. norvegicus shows at the apical end a cylindrical capsule about 17 ¿m in length and 2 ¿m in diameter occupied by the acrosome. The spherical nucleus of 4 to 5 ¿m presents a fibrillar and little dense chromatin. The nuclear envelope is difficult to observe since it is intimately attached to the plasma membrane. A cytoplasm region with two orthogonal centrioles are found between the apical capsule and the nucleus, as well as some mitochondria of small size and three thin cytoplasmic expansions or lateral arms of about 35 m in length. In the interior of these lateral arms, a large number of microtubules are seen in parallel arrangement and located between the membranous sheets (laminar systems) that are arranged longitudinally in each one of the lateral arms. These laminar systems and microtubules seem to originate in the region of the cytoplasm near centrioles and mitochondria. The structural complexity of these laminar systems is simplified as we move from the base to the end of the lateral arms