【摘要】 应用光镜和电镜技术,系统观察冬眠中华鳖(Trionyx sinensis)雌、雄生殖道的精子储存情况,显示与精子储存相关的形态结构和细胞特征。结果表明,中华鳖在冬眠期生精活动处于相对静止状态,仅有1～3层精原细胞排列在睾丸曲细精管基膜附近,其余生精细胞排列松散而紊乱,生精上皮中未见有各级细胞规律性排列,不能形成完整的管壁。附睾管腔增大,腔中储存有大量精子。附睾上皮及附睾管腔中见有PAS反应阳性物质。附睾上皮主要由主细胞、亮细胞和基细胞组成。超微结构显示,附睾上皮细胞中含有大量分泌颗粒,内质网膨大。储存在附睾中的精子结构完整,精子中段由35～40个同心圆状线粒体构成线粒体鞘,中段胞质中含有大量糖原颗粒。雌性输卵管分布着数量不等的精子,尤其狭部最多。狭部黏膜皱襞高度融合,形成大量纵行于输卵管的储精细管。在细管中含有大量精子,精子头部嵌入上皮细胞纤毛中。蛋白部和子宫部也有少量精子存在,但在这些部位不能形成明显的储精细管。PAS反应显示,输卵管狭部储精细管上皮分泌有糖蛋白类物质。储精细管上皮下固有层中分布有大量的管状腺,通过腺导管与输卵管管腔相通。雌、雄中华鳖隔离4个月(12月初至来年3月底)后,在雌性输卵管峡部的储精细管中仍可观察到大量结构完整的精子,表明中华鳖精子在输卵管中至少可以储存120 d。以上结果显示,在冬眠期,雄性附睾和雌性输卵管中有大量精子储存,储存的精子能够渡过漫长的冬季用于来年春天交配或受精,这一特殊的生殖策略对其成功繁殖具有重要意义。本研究还对中华鳖的繁殖特性进行了讨论。更多还原

【Abstract】 Sperm production,mating and ovulation are out of phase with one another in numerous species.In turtles,spermatogenesis is an episodic event,commencing in early summer(June).Sperm leaves the testis and enters the epididymis in autumn(September October).Athough oogenesis is initiated at about the same time as spermatogenesis,ovulation does not occur until the following spring.Thus,for autumn breeding turtles,sperm may be stored over winter in the oviductal glands of females,or,for spring-breeding turtles,in the epididymis of the male.Soft-shelled turtle,Trionyx sinensis are distributed widely in China and this species is famous for commercial and pharmacological value.This species exhibits an unusual reproductive cycle whose spermatogenesis and ovulation are out of phase with each other.Therefore the sperm is obligated to be stored in males or females,which is similar to other reptiles.Reproductive ducts of male and female soft-shelled turtle,Trionyx sinensis were examind in hibernation(December to next March)under light and electron microscopes(SEM and TEM) to determine the location and histomorphological characteristics of sperm storage structure.In male,spermiogenesis was inactive in winter,only 1-3 layers of resting spermatogonia are arranged closely to the base membrane.A few sperm dispose themselves loosely in the lumen of the seminiferous tubule,which are remnant germ cells from the previous year.The seminiferous epithelium is quiescent and there is no consistent cellular association or process of spermiogenesis at this stage.Epididymis duct becomes large and a large number of spermatozoa are stored.Cells comprising the pseudostratified epithelium of the epididymis are principal cell,base cell and clear cell.The PAS-positive materials secreted from the epithelium of the epididymis were observed,which might have the function of nourishment for the sperm to survive longer.The rough endoplasmic reticulum(RER) presented in the whole cytoplasm and the cisternae of RER are inflated due to the fallness of the secretory materials.Sperms stored in the epididymis are integrated which have 35-40 concentric mitochondria forming the mitochondrial sheath in the middle piece of the spermatozoon.The concentric cristae mitochondriales and lots of glycogens in the cytoplasm of the middle piece show the relationship to the vitality maintaining during long-time storage of the spermatozoon in the turtle.Various quantities of spermatozoa were observed in the cavity of the oviduct including tuba uterina,isthmus and uterus.However,most spermatozoa were distributed in the sperm storage tubules(SST) in the isthmus.The mucosa of isthmus shows extensive foldings and convolutions.A majority of mucosa fused into sperm storage tubules orientated toward the longitudinal axes of the oviduct.These tubules developed either by folding or fusion of the oviductal mucosal folds and were lined by both ciliated and secretory epithelial cells.Tubular glands distribute in the inner mucosa.They communicate with the oviduct lumen via short openings composed of invaginations of the epithelium.PAS-positive materials secreted from the epithelium were observed in sperm storage tubules of the isthmus.Sperm might get nutrition from the epithelium of the sperm storage tube and the gland in the in the inner mucosa.After being separated for 4 months(December to March next year),the sperms were observed in the tubules of the isthmus,most of which housed themselves with the head orientating toward epithelium in the SST,even some spermatozoa embed their head in the cilia of the ciliated cells and kept their tails towards to the cavity of the SST.Although we do not know whether these females have finished mating in spring or autumn,the sperm can be stored in the oviduct of the female at least 120d.In conclusion,sperm can be stored both in the epididymis of the male and the sperm storage tubules in the isthmus of the oviduct in hibernation.This strategy is necessary for the turtles to breed successfully.We also discuss the reproductive characters of the soft-shelled turtle,Trionyx sinensis in the study.更多还原