IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
artículos
Título:
An ectaquasperm-like parasperm in an internally fertilizing gastropod
Autor/es:
WINIK, B.C., CATALáN, N. M., GAMARRA-LUQUES, C. & CASTRO-VAZQUEZ, A.
Revista:
INVERTEBRATE BIOLOGY
Editorial:
Blackwell Publishing
Referencias:
Lugar: Oxford - UK; Año: 2008
ISSN:
1077-8306
Resumen:
Pomacea canaliculata is an internally fertilizing gastropod which produces, besides
fertilizing sperm (=eusperm), a large number of unfertile sperm (=parasperm) which have
no chromatin, are fusiform and have 3-5 flagella. We report here that this snail also
produces another type of parasperm, which results from a peculiar spermiogenesis
including a forward cytoplasmic migration. The mature oligopyrene parasperm has (1) a
rounded head including a partly lysed nucleus, (2) a conical mid-piece with eight large
mitochondrial structures, and (3) a single, long flagellum (about 20 ìm). These characters,
though not found in any other gastropod parasperm, are shared with the externally
fertilizing ectaquasperm and with the early spermiogenetic stages of internally fertilizing
introsperm found among the Annelida and basal Mollusca. There are indications that this
sperm type may be produced by a truncation of euspermiogenesis, as proposed by
Buckland-Nicks and Scheltema (1995) for the expression of ectaquasperm in bilaterian
evolution.is an internally fertilizing gastropod which produces, besides
fertilizing sperm (=eusperm), a large number of unfertile sperm (=parasperm) which have
no chromatin, are fusiform and have 3-5 flagella. We report here that this snail also
produces another type of parasperm, which results from a peculiar spermiogenesis
including a forward cytoplasmic migration. The mature oligopyrene parasperm has (1) a
rounded head including a partly lysed nucleus, (2) a conical mid-piece with eight large
mitochondrial structures, and (3) a single, long flagellum (about 20 ìm). These characters,
though not found in any other gastropod parasperm, are shared with the externally
fertilizing ectaquasperm and with the early spermiogenetic stages of internally fertilizing
introsperm found among the Annelida and basal Mollusca. There are indications that this
sperm type may be produced by a truncation of euspermiogenesis, as proposed by
Buckland-Nicks and Scheltema (1995) for the expression of ectaquasperm in bilaterian
evolution.