Preliminary Study Of Gobiocypris Rarus Spermatogenesis

Rare minnow (Gobiocypris rarus), a small freshwater fish endemic to China, is a member of Gobiocypris genus, Cyprinidae family and Cypriniformes order. In this dissertation, a reseach is carried out through anatomy, histology, and transmission electron microscope o study the testis structure, spermatogenesis, and ultrastructure of spermatozoa of Gobiocypris rarus, and the finding are as follows:1.The male rare monnow has two testes, which are located in the dorsal abdomen, above the swim bladder. The two testes joint into one paragraph at the end of body cavity, and open to a gonopore,which accounts for 1/3 length of the whole merger part, at the back of which the testes show a "Y" shape. The testicle of juvenile fish is a transparent fine line, which may not be easily distinguished by naked eyes, while along with the growth of the young fish, it increases in thickness, and finally grows into the shape with a long cystic, bulky front-end, while a thinner backward part. However, a mature testicle is milky white in color with full body cavity expansion, the mesangium of the testicle is visible on the obvious blood vessels, and the semen will flow out with a gentle press on the abdomen of the fish.2.Consisted of the outer membrance and the substance part, rare monnow is a typically lobular type, the former, comprised of serosa, connective tissue and flexible fiber, wraps the latter completely inside,while the latter is divided into three parts,namely, interlobular septum, lobular cavity and seminiferous lobule. In addition, the cyst is the basic unit of testes,the germ cells in one cyst has the same phase, but in different cyst the germ cell may not be in the same phase.3.The spermatogenesis of rare minnow undergoes the stages from spermatogonium to primary spermatocyte and then secondary spermatocyte and spermatid before it develops into sperm. Spermatogonium is the largest germ that can be divided into type A and type B, the former is similar to the latter in morphology, except that the former has an obvious nucleolus but the latter does not. The number of organelles of spermatogonium is larger than that of spermatocyte, which is oval in shape. The formation of spermatozoa includes three periods:prophase, metaphase and anaphase.4. A mature sperm consists of a head, a mid-piece and a tail:the head contains a nucleus,whose tip has no acrosome while back is hollow entad, and the mid-piece, mainly made up of centriolar complex and sleeve, is closely connected to the head; meanwhile, the tail is slender without lateral fins and the cross-section of its flagellum is a typical "9+2" pattern; in addition, there are some sacciform structures at some parts of the tail.5.The non-germ cells inside the testis of rare minnow are consisted of sertoli cells, leydig cells, fibroblast, boundary cell,etc,which are dispersed inside Seminiferous lobules and function as reinforcement, support as well as nutritious supply.