The Ultrastructure Of The Testis Of The Black Snake (zaocys Dhumnades)

Zaocys dhumnades(Serpentiformes:Colubridae) are large non-toxic snakes particular in China, which are located in 21 provinces,mainly feeding on Batrachia,playing an important role in maintenance of balance between agriculture,forestry,ecological system,in this paper,the morphologic characters and ultrastructure changes of varieties spermamatogenous cell,spermatozoa, sertoli cells and leyding cells in adult male Chinese Rat Snake(Zaocys dhumnades) were observed during the process of spermatogenesis using transmission electron microscopy techniques.The significances of the work lie in,not only for understanding the law of spermatogenesis in Zaocys dhumnades,enriching contents of reptile reproductive biology,but also for artificial feeding and reproduction of Zaocys dhumnades,the effective conservation of wildlife resources,rational development and use.The main results and conclusions were as follows:1.The spermatogenesis of Chinese Rat Snake in May and June,spermatogenesis is active from July to October and spermiogenesis is high peak in September.Based on the results and reported data,our results suguset that the spermatogenetic cycle is of discontinuous type,and the reproductive tyle of Chinese Rat Snake belongs to postnuptial.2.Acrosome granulum in proacrosomal vesicle confluens an acrosomal granule and it disappears in stageⅡin the process of spermiogenesis of Cninese Rat Snake.In the process of spermiogenesis of tetrapoda,acrosomal vesicle does not appear in amphibian,but acrosomal vesicle appears in amniota(reptile,birds and mammals).Based on the results,our results suguset that the acrosomal vesicle appears in the process of spermiogenesis is common characteristic.3.An electronics transparent acrosomal vesicle appears in the process spermiogenesis of Cninese Rat Snake.In the process of acrosom formation,electronics transparent acrosomal vesicle appears in the amphibian and reptile,acrosomal vesicle disappears in the birds,but a dense acrosomal vesicle appears in the mammalian.Based on the facts,in the system evolve of tetrapoda, reptile reserve electronics transparent acrosomal vesicle which reserved in amphibian;the mammalia reserve acrosomal vesicle which reserved in amphibian and reptile,but in the system evolution process transparent acrosomal vesicle changed a dense acrosomal vesicle;but birds is an branch of reptile,in the system evolution process acrosomal vesicle disappeared in modem birds.Furthermore, the whole acrosomal vesicle sink into the nucelus in the process of spermiogenesis of Cninese Rat Snake and nuclear umbilication is round.Compare to other snake and lizards,the position of acrosomal vesicle and the position of nuclear existence difference in squamate in the process of spermiogenesis.4.Middle section and main piece of sperm of Chinese Rat Snake have peripheral dense fiber. Middle section and main piece of sperm of other squamate and mammals also have peripheral dense fiber.Birds have not peripheral dense fiber,or only have peripheral dense fiber in middle section or main piece of sperm,or both have Middle section and main piece of sperm in middle section and main piece of sperm.These results prove that squamate closely relate to mammals.Furthermore,the Chinese Rat Snake sperm have single perforatorium and ex-nucleus electronics lucent area,its mitochondria cristae present lines and its sperm have no intranuclear canaliculi.Compare with other snake,lizard,turtle,we know that some structures,for example,the quantity of the perforatorium, the shape of mitochondria cristae,the existence of the intranuclear canaliculi and ex-nucleus electronics lucent area,exist obvious diversity in different reptile group.It illustrates that the sperm structure of reptile have variety morphological character.5.The arrangement modus of the middle piece mitochondria in the Chinese Rat Snake is identical with the other snakes,the mitochondria twist outside of the fibrous sheath.But,there are 9-10 mitochondria in every cycle in the colubrid,for example,the Elaphe taeniurus Cope,the colubrid and the Chinese Rat Snake.And there are 16-17 in the vipers,for example Gloydius brevicaudu. Seen from the recent accumulative numerical data,although the arrangement modus of the middle piece mitochondria is identical in the colubrid and vipers,but the quantity in every mitochondrion in the two Famliy is very different.6.There are plenty of smooth endoplasmic reticulum,lipid droplet and mitochondria in sertoli cells.These characteristics reveal that the sertoli cells might have the function of secreting steroid. On the cytoplasm,there are some glycogen that nourish the spermatozoa,and some primary lysomes, residual bodies and myelin body that show the phagocytosis function.7.There are plenty of smooth endoplasmic reticulum,lipid droplet and mitochondria in leyding cell.These characteristics reveal that the ieyding cell might have the function of secreting steroid. Moreover,the morphological structure of Leydig cells is various in different seasons,which is positive correlated with the serum testosterone concentration.Our results suggest that Leydig cells in Chinese rat snake engage in secretion of testosterone steroid hormones.