Male reproductive system of the arrow crab Stenorhynchus seticornis (Inachoididae)

Abstract

Our aim was to describe the reproductive system of males and the formation of sperm packages in the seminal receptacle (SR) of recently mated females of the arrow crab Stenorhynchus seticornis. The male reproductive system was analyzed, and was described using light microscopy and histological and histochemical methods. The first pair of gonopods was described by means of scanning electron microscopy. Additionally, the dehiscence of spermatophores was tested using samples obtained from the vas deferens of males and from the seminal receptacle of recently mated females. Testes were tubular type, and each vas deferens consisted of three regions: the anterior vas deferens (AVD), including a proximal portion that was filled with free spermatozoa and a distal portion contained developing spermatophores; the median vas deferens (MVD) that contained completely formed spermatophores; and the posterior vas deferens (PVD), which contained only granular secretions. The accessory gland, which was filled with secretions, was located in the transition region between the MVD and the PVD. The spermatophores from the MVD were of different sizes, and none of them showed dehiscence in seawater, whereas those spermatophores in contact with the seminal receptacle were immediately broken. The ultrastructure of the gonopods revealed the presence of denticles at the distal portion, which contribute to the mechanical rupture of the spermatophore wall during the transfer of sperm. The contents of the PVD and accessory gland of males are transferred together with the spermatophores, and are responsible for the secretions observed among the sperm packets in the SR of the female. We suggest that these secretions formed the layers found in the SR of recently mated females, and may play a role in sperm competition in arrow crabs.

Integrative depiction of the male reproductive system of the commercial purple crab Homalaspis plana (Platyxanthidae): Structure and function

“…Spermatogenesis and spermiogenesis in H. plana follows the pattern of primary spermatocytes with chromosomes in the meiotic prophase, and secondary spermatocytes with homogeneous and less voluminous nuclei. The spermatids increase the PAS‐positive acrosomal vesicle at the same time as the nucleus becomes cup‐shaped as described in many other crabs belonging to Podotremata and Eubrachyura (Antunes et al, ; Garcia Bento et al, ; Nascimento & Zara, ; Oliveira & Zara, ; Tiseo et al, ; among others). The main finding of spermatozoal histochemistry is that the perforatorial chamber wall and operculum are composed of proteins, as does the basophilic nucleus.…”

“…As expected, spermatophore formation took place in the AVD like fully reported in the literature (review see Diesel, ; López‐Greco, ; McLay & Becker, ). The AVD shows acidophilic and basophilic glycoprotein secretions, which separate the sperm mass into discrete spermatophores in the distal portion (Antunes et al, ; Oliveira & Zara, ; Stewart et al, ; Tiseo et al, ). However, there are no acidic polysaccharides acting in the formation of the spermatophores as observed in the sperm plug of Callinectes danae and C. ornatus (Nascimento & Zara, ; Zara et al, ).…”

“…Each testis is typically lobular where spermatogenesis occurs in the seminal tubules and sperm are transported to the vas deferens (VD) by the seminal ducts (Johnson, ; Krol, Hawkins, & Overstreet, ; Zara, Toyama, Caetano, & López‐Greco, ). In most species, including basal crabs, the VD is often large and highly convoluted duct (Antunes, Zara, López‐Greco, & Negreiros‐Fransozo, ; Garcia Bento, López‐Greco, & Zara, ), however, the VD can also be sinuous and short as in Metacarcinus edwardsii (Pardo, Fuentes, Oluín, & Orensaz, ). Regardless of its complexity, the vas deferens has three major regions (anterior, middle, and posterior).…”

“…In certain groups the PVD can have accessory glands, caeca (Majidae, Inachoididae, Trichodactylidae, and Grapsidae) or outpocketings (Portunidae). All these structures are important for spermatophore transfer because they can lead to the development of different strategies of sperm competition (Antunes et al, ; Johnson, ; Oliveira & Zara, ; Sainte‐Marie & Sainte‐Marie, ; Tiseo, Zara, & Mantelatto, ; Zara et al, ). The vas deferens ends in a short ejaculatory duct leading to the gonopore and gonopod.…”

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

“…Subsequently, the samples were washed three times (15 min each) in the same buffer and dehydrated in an increasing alcohol series of 70%–90% during 30 min, and two baths of 1 hr each in 95% alcohol. After dehydration, the material was embedded in glycol methacrylate historesin Leica ® , according to routine procedures (Antunes, Zara, López Greco, & Negreiros Fransozo, ). Serial sections 5 μm in thickness were obtained with a rotary microtome.…”