Study On The Differentiation Of Gonad And The Effects Of Temperatures On It In Trionyx Sinensis

The primordial germ cells (Primordial germ cells, PGCs) are the precursors of the germcells. Studying the origin, migration and differentiation of PGCs is an important part of theanimal reproductive and developmental biology. The article studied the origin, migration,path and time of differentiation of the Trionyx sinensis PGCs by observing the tissue sectionsof the T. sinensis embryos of different developmental stages and immunohistochemicalmethods. The article explored the early sex identification standards of T. sinensis in juvenilesthrough the analysis of secondary sexual characteristics. On the one hand, this article providea basic reference for the study of reproductive and developmental biology of T. sinensis, andon the other hand, it provide a scientific basis for the male T. sinensis fry breeding.The study of the origin, migration and differentiation of PGCs showed that the origin ofprimordial germ cells in T. sinensis is the ectoderm, and they migrate to the germinal crescentfor proliferating after24h’s incubation, and then migrate to the blood vessels in umbilicalmesentery, and then migrate to the vicinity of the genital ridge. During the incubation, whenthe temperature was32±0.5°C, the genital ridge uplift from8th day. On the13th day, thegenital ridge developed into primitive gonads.we can told some differences between male andfemale individuals after19days’ incubation. After21days’ incubation, the gonad completedits differentation, forming the testes and ovaries.The temperature impact to T. sinensis gonadal development and sexual differentationshowed that: in the range of26℃~36℃, the higher the incubation temperature was, theshorter the incubation time required. The hatching rate were higher than any other groupswhen the incubation temperature were32℃and34℃. The hatching rate plummeted whenthe temperature was36℃. Comparing the other groups, male ratio was highest when thetemperature was32℃, but the difference of the results was not very clear.Study about the sexual characteristics of T. sinensis showed that, there is no obviousdifference between the ratio shell length/shell width of male and female juvenile turtle.Theratio tail length/tail width, tail length/width skirts data showed that female turtle is greater than the male turtle, and the statistical analysis showed significant differences. The ovary ofnewly hatched juvenile turtle was long fusiform, located kidney medial, oogonia can be seenin the dissecting microscope,they are granular arranged in the ovarian cortex. The milkywhite oviduct was on the other side of the kidney.The testis was linear, and it’s transversediameter was shorter than the ovary. The difference of external genitalia between male andfamale juveniles in not very clear.Nanos1gene expression studies have shown that, in the gonads of the T. sinensis embryos,only germ cells can express nanos1, while the interstitial cells can not. The ovary has highernanos1expression levels in than the testis. Nanos1was also found in kidney. Whether nanos1has multiple function,and whether its deletion can impact the normal development of gonad,and so on, these aspects need further research to determine.