STRUCTURE OF THE TESTES, SPERMATOZOA AND SPERMATOZEUGMATA OF MIMAGONIATES-BARBERI REGAN, 1907 (TELEOSTEI, CHARACIDAE), AND INTERNALLY FERTILIZING, OVIPAROUS FISH
A. Pecio et J. Rafinski, STRUCTURE OF THE TESTES, SPERMATOZOA AND SPERMATOZEUGMATA OF MIMAGONIATES-BARBERI REGAN, 1907 (TELEOSTEI, CHARACIDAE), AND INTERNALLY FERTILIZING, OVIPAROUS FISH, Acta Zoologica, 75(3), 1994, pp. 179-185
The testis of Mimagoniates barberi is bipartite. Spermatogenic tissue
is restricted to the anterior part. The posterior part of the testis i
s devoid of spermatogenic tissue and contains numerous efferent ducts
filled with mature sperm. Cells in germinal cysts develop synchronousl
y, sperm nuclei and flagella become oriented parallel in the late stag
es of spermiogenesis. In the caudal portion of the aspermatogenic part
all sperms are arranged into unencapsulated sperm bundles -spermatoze
ugmata. Two types of spermatozeugmata are found both in the caudal por
tion of the testis and in milt. In the larger, spindle-shaped type, sp
erm flagella form the spindle tips. In the smaller ones, which have ap
proximately a length of spermatozoon, the sperm are parallel and appro
ximately in register. In both types sperm heads are arranged parallel.
A mature spermatozoon is flail-shaped. The sperm head is highly elong
ated and situated alongside the flagellum, the tip of the head is dire
cted backwards. Large mitochondria are situated on one side of the elo
ngated nucleus only and form the tip of the head. Live spermatozoa mov
e with the centriolar part ahead. Both testis and spermatozoon structu
re as well as formation of spermatozeugmata in M. barberi are highly d
erived features which perhaps evolved as adaptations to internal ferti
lization.