S. Goffredo et al., Ultrastructural observations of the spermatogenesis of the hermaphroditic solitary coral Balanophyllia europaea (Anthozoa, Scleractinia), ZOOMORPHOL, 119(4), 2000, pp. 231-240
Spermatogenesis ultrastructure was studied in a simultaneous hermaphrodite
population of the solitary coral Balanophyllia europaea. In this species, s
permatogenesis takes place in spermatocysts located within gametogenetic me
senteries surrounded by a bilayered boundary. Spermatogonia and spermatocyt
es are large flagellate cells, densely packed at the outermost edges of the
spermatocyst. Spermatids and sperm are loosely distributed near the centre
of the spermatocyst. The cytoplasm of spermatogonia and primary spermatocy
tes often contains short lengths of free axonemes, probably derived from th
e reabsorption of a primitive flagellum. Maturing spermatids either contain
long intracytoplasmic axonemes, that may be stages of the tail synthesis,
or have a flagellum. The morphological features of the sperm of this hermap
hroditic scleractinian, very similar to those observed in the sperm of gono
choric taxa, support the hypothesis that the hermaphroditism of this popula
tion is an adaptive condition.