New insights in the male anatomy, spermatophore formation, and sperm structure in Atyidae: The red cherry shrimp Neocaridina davidi

• Published in: Invertebrate biology Vol. 138; no. 1; pp. 17 - 28
• Main Authors: Tomas, Ana Laura, Garcia Bento, Maria Alice, Mutti, Leonardo Damian, Zara, Fernando José, López Greco, Laura Susana
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.03.2019
• Subjects: Anatomy; Caridea; Cells; Cephalothorax; Composition; Decapoda; Electron microscopy; Epithelium; Freshwater crustaceans; Functional anatomy; Glycoconjugates; Hepatopancreas; Histochemical analysis; histochemistry; histology; Males; Morphology; Neocaridina davidi; Proteins; Reproductive system; Shrimps; Sperm; sperm ultrastructure; Spermatogenesis; Spermatophores; Spermatozoa; Testes; Transmission electron microscopy; Tubules; Ultrastructure; Vas deferens
• ISSN: 1077-8306; 1744-7410
• DOI: 10.1111/ivb.12239

This study aims to analyze the functional anatomy of the male reproductive system in Neocaridina davidi, a very popular ornamental species of caridean shrimp. Mature males were cold‐anaesthetized and their reproductive systems were dissected for histological and histochemical analysis, while the spermatozoa and spermatophore wall ultrastructure were analyzed under transmission electron microscopy. The male reproductive system consisted of two coiled testes, which were continuous with the vasa deferentia. Testes were positioned on the dorsal side of the cephalothorax above the hepatopancreas, and comprised seminiferous tubules where spermatogenesis occurred. Each vas deferens (VD) was a long tube dorsolaterally positioned with respect to the hepatopancreas, and increased in diameter at the distal end. Three regions could be recognized in the VD: proximal, middle, and distal. The proximal region had a cylindrical epithelium with secretory cells. The middle region (or typhlosole) had a dorsal fold (or typhlosole) with a thick columnar epithelium and high secretory activity. The spermatophore was a continuous cord with three acellular layers, which were mainly characterized by the presence of neutral glycoconjugates and proteins. The sperm morphology was distinct from the inverted cup‐shaped spermatozoa observed in the majority of caridean shrimps. The spermatozoa in specimens of N. davidi were spherical in shape, with a cross‐striated, single, short spike, and arranged in clusters of three or four sperm cells. The composition of the spermatophore, and the arrangement and form of the spermatozoa, seem to be unique in comparison to other species of Caridea.