STUDIES ON THE GONADAL DEVELOPMENT OF A CHINESE TURTLE (TRIONYX SINENSIS)

We discovered the year rings in the scapular bone of Trionyx sinensis and by which the age for sexual maturity of the turtle has been determined to be four years. The mature females spawn 3—5 times per year, each time it generally lays 8—12 eggs and at most 20—26 eggs. Hence the female turtle belongs to the type of spawning several times a year. A fully mature egg, which is differentiated from oogonium 8—10 micron in dimeter, reaches 17—20 mm in diameter. The entire course of oogenesis, from oogonium to mature egg, can be divided into four stages, i. e. oogonium, primary follicles, growing follicles and mature follicles.We observed that the microvilli on the sur face of oocyte insert into the radial membrane during the growing follicular stage; this structure may be related to the transportation of substances which are necessary for the formation of volk.No seasonal changes of the normal formation and existence of spermatozoa have been found in the seminiferous tubules. Our research also discovered that the spermatozoa which enter female's oviduct in the summer or autumn could retain their capacity of fertilization in the reproductive season of the next year.