Despite that Liza carinata (Mugiliformes: Mugilidae) is economically important
fish of the Red Sea, little information is known about its testicular cycle. Moreover, a
good understanding of the reproductive parameters of a fish such as the gonadal
development, sexual maturation, gonado-somatic index and spawning season, is of
paramount importance for the fisheries management. So, the present study is aimed to
gain more information about the morphology, histology and ultrastructure
characteristics of male L. carinata during its reproductive cycle.
According to the seasonal variations in the gonado-somatic index of males L.
carinata, the year can be divided into three seasons, namely: the pre-spawning season
(from early June to late August), the spawning season (from early September to Late
December) and the post-spawning season (from early January to late May). The average
values of gonado-somatic index were small in the pre-spawning season and then they
increased sharply to reach the highest value in the spawning season. The values of GSI
decreased gradually to reach the smallest value in the post-spawning season.
Histologically, the testis of L. carinata is formed of a large number of highly
convoluted seminiferous lobules. Each seminiferous lobule is divided into numerous
isogenic cysts which contain different stages of the spermatogenic cells that enclosed by
the Sertoli cells. Six stages of the spermatogenic cells can be identified in the
seminiferous lobules during the different seasons, namely: the spermatogonia A and B,
primary and secondary spermatocytes, spermatids and spermatozoa. In addition, the
ultrastructural examination revealed that the spermatids are differentiated into three
different stages, namely: the early, middle and late spermatids. The spermatozoa have
similar structure to those of fish that breed through external fertilization, thus
classifying them as uniflagellate anacrosomal aquasperm.