Sperm ultrastructure in Bathypolypus bairdii and B. sponsalis (Cephalopoda: Octopoda)

Abstract

Ultrastructural comparison of the octopods Bathypolypus bairdii and B. sponsalis have been carried out by electron microscopy. Although the mature spermatozoon of B. bairdii is longer and thinner than that of B. sponsalis, its general ultrastructure is similar except for some minor differences. Their characteristic acrosomes, described here for the first time, consist of a periodically banded cone surrounded by a double 15 helix whose arrangement has been defined by a numeric expression. The plasma membrane of sponsalis that surrounds the acrosome has many projections filled with abundant granular cytoplasm, which appears as a star-shaped acrosome in cross section. The mitochondrial sheath contains nine to eleven mitochondria in bairdii but only nine in sponsalis. A comparison with other Octopodidae shows that the nucleus of both species is the largest ever seen. Our results support the capability of sperm morphology to 20 discriminate between species and could even discern at higher taxonomic levels.

Ultrastructure of spermatozoa and spermatogenesis inOctopus minor(Sasaki, 1920) (Cephalopoda: Octopoda)

“…Morphologically, the sperm of O. minor resembles the other species in Octopodidae, Eledoninae and Graneledoninae (Galangau and Tuzet 1968a;Leik 1970;Longo and Anderson 1970;Giménez-Bonafé et al 2002;Ribes et al 2002;Roura et al 2009), because it consists of a single helix surrounding the acrosome ( Figure 2O). This feature distinguishes it from Bathypolypus species in Bathypolypodinae with a double helix surrounding the acrosome (Roura et al 2010a). By comparison with Eledone spp., Maxwell (1974) described an internal ladder-like structure in the mature helical acrosome of Octopus.…”

“…Sperm size ranges from 280 μm to 1130 μm in the reported species of Octopodidae (Maxwell 1974;Healy 1993;Selmi 1996;Roura et al 2009Roura et al , 2010aRoura et al , 2010b.…”

“…The morphology and formation of cephalopod spermatozoa have considerable potential in systematics (Healy 1989), and much research has been conducted on sperm morphology and spermiogenesis of cephalopods (Franzén 1955(Franzén , 1967Maxwell 1974Maxwell , 1975Maxwell , 1983Fields and Thompson 1976;Arnold and Williams 1978;Healy 1990aHealy , 1990bHealy , 1993Selmi 1996;Giménez-Bonafé et al 2002;Ribes et al 2002;Martínez et Roura et al 2009Roura et al , 2010aRoura et al , 2010b. However, only a few Octopus species have been investigated regarding sperm ultrastructure (e.g.…”

On gonadic maturation and reproductive strategy in deep-sea benthic octopus Graneledone macrotyla

“…Nonetheless, the absence of spermathecae in the oviducal glands and the presence of fertilized eggs inside the ovary of G. macrotyla suggest that fertilization takes place within the ovary. On the other hand, considering the relationship between sperm morphology and the mode of fertilization (Franzén 1955;Healy 1988), the type of spermatozoid found in the Graneledoninae (Roura et al 2009) suggests a mode of fertilization in this subfamily which is more similar to that in the Octopodinae (Longo and Anderson, 1970) and the Bathypolypodinae (Roura et al 2010) than to that displayed by the Eledoninae (Selmi 1996).…”

Differences in sperm ultrastructure between Mytilus chilensis and Mytilus galloprovincialis (Bivalvia, Mytilidae): could be used as a taxonomic trait

“…Initially it was used in mammals and then it was confirmed as valid for other animals including bivalve mollusks (Drozdov & Reunov, 1986). For example, it has been used to identify and classify species of the genus Mytella (Bivalvia) (Soot-Ryen, 1955), considering the presence of the axial rod (Introini et al, 2010), or to taxonomically differentiate species of the genus Bathypolipus (Cephalopoda) (Grimpe, 1921), using and comparing features of the acrosome (Roura et al, 2010). Also, Yurchenko (2012) indicated the species-specific differences in the sperm ultrastructure within the Ostreidae (Rafinesque, 1815), which could be identified both ultrastructurally and morphometrically.…”