Male reproductive system of the fish ectoparasiteArgulus bengalensis(Crustacea: Branchiura)

Abstract

The male reproductive system of the fish ectoparasite Argulus bengalensis was reconstructed with serial histological sections through longitudinal and transverse planes and the description was re-evaluated after the discovery of spermatophore. The study revealed that the testis of A. bengalensis consists of two lobes, each comprised the two enclaves. The outer enclaves from both lobes are connected proximally with an isthmus. The inner enclave is covered with two layers of chromatophores which are presumably involved in androgenic hormone production. At the proximal end of the inner enclaves a pair of vasa efferentia originates and ascends into thorax where it leads into vesicula seminalis. Like Dolops ranarum, a pair of spermatophoric glands is found in the thorax just behind the second maxilla. Glandular cells of the spermatophoric glands are columnar with a large nucleus at their basal side. A pair of spermatophoric canals carries the secretion of the glands into the vesicula seminalis through vasa efferentia. Spermatophores are delivered to the female through a median vas deference originating from the vesicula seminalis. In addition to the spermatophoric glands, a pair of accessory glands is located in the coxa of the fourth thoracic legs. At the region dorsal to the isthmus both the spermatophoric canal and accessory gland ducts unite with the vas efferens of the respective side. The secretion of the accessory gland presumably contributes to semen composition of the parasite.

Histological and ultrastructural investigation of the female reproductive system of Argulus bengalensisRamakrishna, 1951 (Crustacea: Branchiura)

“…For schematic drawing, the sections were stacked with ImageJ (Wayne Rasband, National Institutes of Health, Bethesda, MD; available at http://rsb.info.nih.gov/ij/index.html) software and viewed with Photoshop CS4 software following the procedure of da Silva Costa et al () incorporating some modifications as described by Banerjee et al ().…”

“…In subsequent studies of the juvenile and adult A. japonicus , Ikuta and Makioka () stated that the oocytes mature and undergo vitellogenesis on the outer surface of the ovarian wall and protrude into the hemocoelic space. Their observations and interpretations raise some valid questions regarding the site of oocyte development, space for oocyte release and the site for fertilization in the current context of knowledge on sperm transfer of the species through the spermatophores (Avenant‐Oldewage and Everts, ; Banerjee et al, 2014b, 2015b). The present investigation is conducted on an Indian species A. bengalensis to answers these questions and resolve the existing ambiguity concerning the ovarian structure and organization of the genital duct.…”

“…Recently, spermatophores have been discovered in A. japonicus (Avenant-Oldewage and Everts, 2010) and their structure and formation are described in A. bengalensis (Banerjee et al, 2014b). Thereafter, an appraisal of the male reproductive system of the parasite had been conducted by Banerjee et al (2015b). On the other hand, a few earlier researchers (Leydig, 1850(Leydig, , 1888(Leydig, , 1889Heller, 1857;Thorell, 1866;Claus, 1875;Stuhlmann, 1891;Wilson, 1902;Grobben, 1908;Maidl, 1912;Martin, 1932) described the structure of the ovary and organization of the female reproductive system of different Argulus species.…”

The morphology of the male reproductive system, spermatogenesis and the spermatozoon of Daphnia magna (Crustacea: Branchiopoda)

“…The testes of D. magna consist of two cylindrical lobes that extend longitudinally along either side of the gut. Across Crustacea, the organization of testes range from fairly simple cylindrical lobes, as observed in Daphnia, to multi-lobed structures that produce spermatophores, as in Argulus bengalensis (Banerjee, Manna, & Saha, 2015). Our analysis shows that the Daphnia testis is comprised of four distinct cell types including striated muscle sheath, inner thin epithelial sheath cells beneath the encasing basal lamina, germ cells, and large somatic The maturation of germ cells within the testes of D. magna starts at the peripheral epithelial layer and progresses inward toward the central region of the testis.…”