Early gonadal development and sex differentiation in rosy barb (Puntius conchonius)

Abstract

The main objective of this study was to describe the early gonadal development and to examine the process of sex differentiation in male and female P. conchonius under laboratory conditions. First evidence of primordial germ cells was observed on the day of hatching. The sex differentiation in leptotene, zygotene, pachytene and diplotene stages was clearly detected. Differentiation started from the mid-mid posterior part of the gonads. Actual sex differentiation occurred between 18-21 days and 36-40 days post-hatching in females and males, respectively. Histological sex differentiation differences were clear between males and females; in males, gonads had a smooth surface, were less stained, arrow-shaped, with germ cells located alone in the stroma, and number of germ cells ranging from two to ten per section, whereas in females, gonads had a rough surface, were more stained, wider, with germ cells multiplying rapidly and forming clusters, and number of germ cells ranged from 2 to 58 per section. The numbers of germ cells within the two gonad types were significantly different in favour of females (P < 0.05). Here early developmental stages of the gonads from 0 to 56 days post-hatch are explained.

Male Gonadal Differentiation and the Paedomorphic Evolution of the Testis in Teleostei

“…In the ostariophysan, C. carpio , the cellular arrangement of the early, undifferentiated gonad has a pattern very similar to the previous reports on basal taxa in Teleostei (Davies and Takashima, ; Timmermans and Taverne, ; Colombo et al, ; Parmentier and Timmermans, ; Winkoop et al, ; Colombo and Grandi, ; Timmermans et al, ; Grandi and Colombo, ; Otani et al, ; Çek, ; Mazzoni et al, ); it is not possible to distinguish between the presumptive male and the presumptive female. However in the Acanthopterygii, here studied, in the percomorph , A. nigrofasciata and in the atherinomorph, P. reticulata , the early cellular arrangement of the undifferentiated gonads is distinctly different from C. carpio , differing in regard to the presumptive males and presumptive females.…”

“…The hypothesis regarding the evolutionary origin of the testicular types in Teleostei comes from the observation of adult gonads. Despite the existence of several studies on gonadal development (Van Den Hurk, ; Davies and Takashima, ; Timmermans and Taverne, ; Colombo et al, ; Parmentier and Timmermans, ; Winkoop et al, ; Colombo and Grandi, ; Timmermans et al, ; Grandi and Colombo, ; Meijide et al, ; Otani et al, ; Çek, ; Nakamura et al, ; Saito et al, ; Nakamura et al, ; Pandolfi et al, ; Guerrero‐Estévez and Moreno‐Mendoza, ; Nakamura et al, ; Kobayashi et al, ), none of them have a focus on the formation of the germinal compartment in the different types of testes in Teleostei.…”

Non‐sex specific genes associated with the secondary mitotic period of primordial germ cell proliferation in the gonads of embryonic rainbow trout (Oncorhynchus mykiss)

“…These germs cells represent two populations with distinct fates, either self‐renewing stem cells or oogonia/spermatogonia poised to enter into meiosis (Schulz et al, 2010). The number of germ cells produced in the embryonic rainbow trout gonad is considerably more than found in some other iteroparous fish that have been examined to date [e.g., medaka (Satoh and Egami, 1972); rosy barb (Çek, 2006); zebrafish (Yoon et al, 1997)], but not unlike others [threespine stickleback (Lewis et al, 2008)]. Different reproductive life history patterns likely explain these differences.…”

“…All the PGCs are concentrated at this point, and can be observed or collected for study. Germ cell numbers have been quantified in the early embryonic fish gonad by histological analyses [medaka, Oryzias latipes (Satoh and Egami, 1972); rainbow trout, Oncorhynchus mykiss (LeBrun et al, 1982); rosy barb, Puntius conchonius (Çek, 2006)], but combining this with unequivocal assignment of genetic sex has not been possible until recently [medaka (Kobayashi et al, 2004); threespine stickleback, Gasterosteus aculeatus (Lewis et al, 2008)]. However, the precise sex‐specific quantification of PGC numbers during the secondary mitotic period and associated molecular events have not been documented in any fish.…”

The Basement Membrane and the Sex Establishment in the Juvenile Hermaphroditism During Gonadal Differentiation of the Gymnocorymbus ternetzi (Teleostei: Characiformes: Characidae)

“…The process that results in the formation of a germline cyst is the same in both sexes (Quagio‐Grassiotto et al, ). The PGCs are individualized, forming germline cysts in which future oogonia or spermatogonia are surrounded and isolated from one another by cytoplasmic processes from SC: the pre‐follicle cells in females (Mazzoni et al, ) or Sertoli cells in males (Parmentier and Timmermans, ; Nakamura et al, ; Meijide et al, ; Otani et al, ; Çek, ; Mazzoni et al, ).…”