Histological Studies On Reproductive System In Male Bactrian Camel (Camelus Bactrianus)

The reproductive system of the male Bactrian camel (Camelus bactrianus) was studied by anatomical, histochemical, electron microscope and immunohistochemical techniques to understand the reproductive characteristics of the system comprehensively. The results showed as following.1. The testes had descended out of the abdominal cavity at about 5-months pregnancy in the Bactrian camelcamel. Before 2-year old, the testicular cords exited without lumens and sperms in testes. The blood-testes barriers were likely composed of desmosomes besides of tight junctions between Sertoli cells, which maybe facility the camels to adapt the circumstance in deserts. Besides the nerve fibers, germ cells and Sertoli cells and Leydig cells also exhibited positive immunoreactivity of several neural markers including neurofilament 200 (NF200), 5-hydroxytryptamine (5-HT), dopamine-beta-hydroxylase (DBH), neuron-specific enolase (NSE) and acetylcholinesterase (AChE) in different patterns respectively, which suggested that these proteins may function in the process of the spermatogenesis and hormonopoiesis in camel testes.2. Different segments of the epididymis in Bactrian camel showed various patterns in histological characteristics, cellular construction and cellular contents, which prompted the hypothesis that the caput, corpus and cauda participated in reabsorption, secretion and phagocytosis, respectively to benefit the maturation and storage of the sperms in epididymis. The microvilli extrapolated from the surface of the cells and tight junctions exited between the cells in the tubular epithelium of the epididymis and vas deferens. The latter may serve as parts of the blood-epididymis or blood-deferens barriers. The ductal damage and sperm leakage in the epididymis were prevalent in Bactrian camel, which may be one of the reasons resulting in low reproductivity of this species. The epithelium of the caput epididymis were smooth in fetus, rough in about 2-years old and smooth again in adult camels, which may result from the faster proliferation of the ductal cells than the interstitial tissue in peripuberty. The positive immunoreactivity of NF200,5-HT, DBH, NSE and AChE were disparately exhibited by the epididymal epithelial cells, few cells of neuroendocrine properties in epididymal interstitium and epithelial cells of penile urethra, respectively. The urethral glands generally exited under the epithelium of the membranous urethra. The flexura sigmoidea penis had developed at the about 5-months pregnancy in Bactrian camel.3. The germ cells, Sertoli cells and Leydig cells from the developing testes of different stages in Bactrian camel exhibited various immunoreactivity of nerve growth factor (NGF) and low-affinity nerve growth factor receptor (p75NTR), which suggested that NGF acted on different cells to regulate the development and functions of the testes. In reproductive tract of male camels, the positive signals of p75NTR only exited in epididymal epithelium of the early embryo, which prompted that NGF acted on p75NTR to modulate the development of this organ only in early pregnancy. In the prostate, glandular cells showed dense positive stain of NGF but no positive of p75NTR, and therefore NGF from the prostate may enter the reproductive tract to influence the motility of the sperms and may funtion in acrosome reaction. No positive immunoreactivity of NGF and p75NTR exited in bulbourethral glands in Bactrian camel.In conclusion, the reproductive system in male Bactrian camel was similar to that in other mammalians while few properties were unique in this species. The results of the research supplied datas to the comparative histology and can serve as references for the reproduction and conservation of the camels.