Spermiogenesis and ultrastructure of the spermatozoon of the trypanorhynch cestode Aporhynchus menezesi (Aporhynchidae), a parasite of the velvet belly lanternshark Etmopterus spinax (Elasmobranchii: Etmopteridae)

Abstract

spermiogenesis and the ultrastructural organisation of the spermatozoon of the trypanorhynch cestode Aporhynchus menezesi Noever, caira, Kuchta et Desjardins, 2010 are described by means of transmission electron microscopy. type i spermiogenesis of A. menezesi starts with the formation of a differentiation zone containing two centrioles separated by an intercentriolar body constituted by five electron-dense plates. Each centriole gives rise to a free flagellum, which grows at an angle of 90° in relation to a median cytoplasmic process. The nucleus and cortical microtubules elongate along the spermatid body. Later, both flagella rotate and fuse with the median cytoplasmic process. At the final stage of spermiogenesis, the young spermatozoon is detached from the residual cytoplasm by a narrowing of the ring of arched membranes. The mature spermatozoon is a long and filiform cell, tapered at both ends, lacking mitochondria. it is characterized by the presence of two axonemes of the 9+'1' trepaxonematan pattern, the absence of crested bodies, the presence of parallel cortical microtubules and nucleus. this pattern corresponds to the type i spermatozoon of the eucestodes. the anterior extremity of the spermatozoon is characterized by the presence of an arc-like row of up to seven parallel cortical microtubules that partially surrounds the first axoneme. These anterior cortical microtubules are thicker than the posterior microtubules and, consequently, the sperm cell of A. menezesi exhibits two types of cortical microtubules. another interesting aspect is the presence of α-glycogen rosettes. This spermatological pattern is similar to that observed in the spathebothriidean and diphyllobothriidean cestodes.

Spermiogenesis and spermatozoon ultrastructure of the bothriocephalidean cestode Clestobothrium crassiceps (Rudolphi, 1819), a parasite of the teleost fish Merluccius merluccius (Gadiformes: Merlucciidae)

“…These structures, observed in C. crassiceps during the present study, are also described in six other Bothriocephalidea namely Paraechinophallus japonicus, Bothriocephalus scorpii, E. crassum, E. rugosum, Oncodiscus sauridae and Senga sp (Levron et al 2006a,b;Šípková et al 2011), in two Diphyllobothriidea namely Ligula intestinalis and Diphyllobothrium latum (Levron et al 2006c(Levron et al , 2009) and in three Trypanorhyncha namely Aporhynchus menezesi, Dollfusiella spinulifera and Parachristianella trygonis (Miquel and Świderski 2006, Miquel et al 2007, Marigo et al 2011b). …”

Revisiting caryophyllidean type of spermiogenesis in the Eucestoda based on spermatozoon differentiation and ultrastructure of Caryophyllaeus laticeps (Pallas, 1781)

“…Spermatozoa are devoid of a crested body in the presumably basal Eucestoda, i.e., caryophyllideans (Świderski and Mackiewicz 2002;Gamil 2008;Bruňanská 2009Bruňanská , 2010Yoneva et al 2011;present study), spathebothriideans Bruňanská and Poddubnaya 2010), diphyllobothriideans (Levron et al 2006b, 2009), haplobothriideans (MacKinnon and Burt 1985, or trypanorhynchs (Miquel and Świderski 2006;Miquel et al 2007b;Marigo et al 2011).…”

Spermatological characters of Acanthobothrium crassicolle Wedl, 1855 (Tetraphyllidea, Onchobothriidae), a parasite of the common stingray Dasyatis pastinaca

“…one Diphyllobothriidea (Justine 1986), in three Trypanorhyncha (Miquel and Świderski 2006, Miquel et al 2007a, Marigo et al 2011, in four Proteocephalidea (Bruňanská et al 2003a(Bruňanská et al , b, 2004b and in two mesocestoidids (Miquel et al 1999(Miquel et al , 2007b. The mature spermatozoon of the five Onchobothriidae studied until now presents two axonemes of the 9 + "1" trepaxonematan pattern (see Table I).…”

“…This is the case of four Caryophyllidea (Arafa and Hamada 2004, Gamil 2008, Bruňanská 2009and Yoneva et al 2011), three Spathebothriidea (MacKinnon and Burt 1984, Bruňanská et al 2006, Bruňan-ská and Poddubnaya 2010, three Trypanorhyncha (Miquel and Świderski 2006, Miquel et al 2007a, Marigo et al 2011, one Bothriocephalidea , three Diphyllobothridea (Justine 1986, Levron et al 2006a, 2009, five Proteocephalidea (Bâ and Marchand 1994;Bruňanská et al 2003aBruňanská et al , b, 2004b and two mesocestoidid Cyclophyllidea (Miquel et al 1999(Miquel et al , 2007b. The number of cortical microtubules forming the arc-like row in all these studies varies between three and eighteen depending on the level of section.…”