Studies On Anatomical Structure Of The Reproductive System And Semen Collection Of The Crested Ibis(Nipponia Nippon)

The crested ibis is one of the rarest of all ibises in the world.Currently,the Crested Ibis is categorized as endangered in the IUCN Red List and listed in Appendix I of CITES.Due to habitat reduction,environmental degradation,inbreeding and irrational genetic structure,the survival,fecundity,and the population of the Crested Ibis decreased rapidly.These complicated factors resulted in the lowest genetic diversity of the Crested Ibis among endangered species in the world.At present,the studies on the anatomical structure of the reproductive system,characteristics and semen collection methods of the Crested Ibis is still unknown.Therefore,it is the first time to reveal the reproductive system anatomy and explore suitable sperm collection methods.Our work will benefit to accumulate basic data and carry out artificial insemination in the Crested Ibis,which will avoid inbreeding,prevent genetic differentiation and maintain the sustainable development of the population.The results are as follows:(1)The anatomical characteristics of the male reproductive system of the Crested Ibis showed that the testes of the juvenile Crested Ibis are yellow,smooth and oblate.The adult testes are white,slightly like oval.The left and right sides of the testis are symmetrical,similar in shape but different in size.The testis of latency period crested ibis were about 0.90±0.008 g,long about 16.98±0.14 mm,and about 8.55±0.51 mm.The testis of young crested ibis were about 0.3851 g,which was about 6.40 mm long and 4.07 mm wide.(2)The histological structure of the testes showed that the testes and seminiferous tubules of the young Crested Ibis were still at the developmental stage,closed cavity,and spermatogenic cells at different stages can be observed.Reversely,the spermatogenic cells at different stages and sperm can be seen in the seminiferous tubules of the testes of the adult Crested Ibis.The vas deferens consists of the outer membrane,muscular layer and the mucous layer.Epididymal is mainly composed of epididymal duct.Single-layer columnar epithelium,blood vessels and nerves distributed in adjacent matrix of the epididymal duct.The length of vas deferens of latency period Crested Ibis is about 14.0±0.5 cm,The central pipe diameter is about 1.26±0.02 mm.(3)The female reproductive system of the Crested Ibis consists of cloacae,ovary,and oviduct.However,only the left ovary and fallopian tube were retained,the right ovary and fallopian tube were degraded after birth.The ovary weights 1.26±0.22 g,17.27± 1.61 mm long and 7.49±1.14 mm width.The length of the oviduct is about 14.83 ± 0.62 cm.(4)In present study,we firstly conduct semen collection on the Crested Ibis using the massage and electro-ejaculation methods.The massage method is not practical for semen collection of the Crested Ibis.However,we have firstly,successfully collected semen of the Crested Ibis by electro-ejaculation in the world.Unfortunately,the collected semen was mixed with the feces and urine,no pure semen was obtained.(5)The sperm of the Crested Ibis is composed of head,neck and tail.The sperm head is bigger and slightly longer,and a obviously acrosome vesicle protruded on the top of the head.The acrosome vesicle protruded is round,and its diameter is about 1.25 um.The total length of the Crested Ibis sperm is about 60~70 um,and about 5/6 of the total length is the tail of sperm.The ratio of head/ tail is about 1:5.4.