| Whitmania pigra is a kind of medicine raw animal, has the effect of anticoagulant, lipid-lowering, anti tumor, and it was frequently used in the treatment of many diseases, such as hypertension, hyperlipidemia and coronary heart disease in clinical, with the deepening of relevant research, W. pigra has been used more widely in the field of biology and medicine, so the demand for it is increasing. And because human intervention in water environment and manual capture increased, its wild resources continue to fall, so, it is extremely urgent to carry out the artificial breeding of W. pigra. Propagation is one of the important problems in artificial breeding, to improve the ability of artificial reproduction, not only can increase farmers’ economic benefits, can also ease the tension of the market. The morphological structure and embryo development of W. pigra were researched in the study, can provide basic data about the artificial breeding and reproduction, disease prevention and control, development and utilization of W. pigra. W. pigra were cultivated in leech’s aquarium we made indoor, the morphological structure was observed based on anatomy and paraffin section in the research. And the major phase of embryonic development was observed through dissected the egg cocoon. The results are follows:(1) W. pigra was androgynous animals, the male reproductive system consisted of the testis and vas deferens, seminal vesicle, ejaculatory bulb, prostate gland, cirrus sac and male gonopor. There were 11 pairs of testis, it was milky white and spherical, it was located in the central of segment for Ⅻ-ⅩⅫ and both sides of ventral nerve cord, each segment with a pair of testis. The testis was covered by film and surrounded by loose connective tissue. Primary spermatocyte, secondary spermatocyte, spermatid and sperm were seen in the testis. There were two vas deferenses, it was longitudinal on both sides of the testis. The vas deferens was covered by membrane and contained many sertoli cells. Seminal vesicle has one pair, milky white and ellipsoida, it was located in the segment of Ⅹ-Ⅻ. Seminal vesicle was composed of a plurality of lumens and filled with sertoli cells and sperm. Ejaculatory bulb also has one pair, milky white and long bone. Ejaculation ball was made of outer membrane, circular muscle layer and simple squamous epithelium. Prostate gland only had one and in the segment of Ⅹ-Ⅻ, it was milky white and enlargement to become globular. Prostate gland was composed of adventitia, muscle layer of circular muscle and longitudinal muscle, and layered columnar epithelium. Cirrus sac also had one, it was milky white and long bone, it opened to vitro through the male gonopor. The penis sheath was also consisted of outer membrane, muscle layer of circular muscle and longitudinal muscle, and simple squamous epithelium, and the penis sheath contained the penis. The penis was formed by cuticle, circular muscle layer and simple squamous epithelium. Male gonopor had one, it was located in the central of 33/34 ring. From the outside in order to cuticle, columnar epithelium and dermis composed of dense connective tissue of male gonopor.(2) The female reproductive system of W. pigra included the ovary, oviduct, albumen gland, vaginal sca and female gonopore. Ovary had one pair, it was ovoid and in the segment of Ⅺ-Ⅻ, each ovary sent one oviduct. Ovary was made of ovarian follicle, and ovarian follicle contained primary oocytes, secondary oocyte and egg cells. Oviduct was composed of loose connective tissue layer, circular muscle layer and columnar epithelium. Two oviducts confluented into total oviduct and passed into the vagina sca, albumen gland wrapped in the periphery in the meeting place. Albumen gland was milky white and long oval. The albumen gland was made of loose connective tissue layer of circular muscle and stratified columnar epithelium. Vaginal sca was also milky white and gourd shaped, it opened to vitro through the female gonopore. Vaginal sac consisted of connective tissue layer, longitudinal muscle layer, layered columnar epithelium. The female gonopore had one, it was located in the central of 33/34 ring and intervaled 5 ring with male gonopor. The female gonopor was composed of cuticle, epidermis and the muscular layer that from exterior to interior.(3) The digestive system of W. pigra consisted of mouth, pharynx, esophagus, crop, intestine, rectum and anus. The mouth was triangle and in the anterior sucker. Mouth was composed of cuticle, epidermis, dense connective tissue and muscle. There were three pieces of jaw, a piece on the back side, the other two in the ventral side, from outside to inside were cuticle, epithelium, muscle layer and jaw cavity. Behind the mouth was pharynx, pharynx was white and muscular long tube, and it was located in the segment of Ⅶ-Ⅸ.Pharynx was composed of mucous layer and longitudinal muscle layer, the mucous layer was composed of simple squamous epithelium and muscularis mucosae, and the mucous layer folded inward formed processes. Behind the pharynx was esophagus, esophagus is slender pipeline and in the segment of Ⅸ-ⅩⅢ, its tube wall was thinner than pharynx’s. The esophagus was composed of simple columnar epithelium and single circular muscle, the epithelium and muscle layer folded inward formed wrinkles. Behind the esophagus was crop, the crop was also slender pipeline and in the segment of ⅩⅣ-ⅩⅩⅡ, esophagus had 11 pairs of blind sacs, and the sixth was the longest and extended back to the rectum. It was different that the front and later part structure of crop, seventh of the parasomal sac as boundaries, the front part was composed of simple columnar epithelium and muscle layer, epithelial inward projections and formed high fold, the cavity of crop was extremely narrow. The later part was also composed of simple columnar epithelium and muscle layer, and epithelium containing microvilli, and the cavity of crop’s later part contains a small amount of food residue. But whether it was in front or rear section, there were many pear shaped and tubular mucous cells. Behind the esophagus was intestine, intestine was a very short and white piping, it was located in the segment of ⅩⅩⅢ. The intestine was made of simple columnar epithelium, loose connective tissue and muscle layer, there were a large pear shaped secretory cells between connective tissue and epithelial, and there were a lot of food residue in intestinal cavity. Behind the intestine was rectum, rectum was long and opened to vitro through anus. The anus was located in the back and ahead of posterior sucker. The structure of rectum was similar to structure of intestine, it was also composed of single columnar epithelium, connective tissue and muscle layer.(4)The nervous system of W. pigra was cable type nerve, it was in the ventral surface of W. pigra and beneath of digestive system. The nervous system included head ganglion, ventral nerve cord and caudal ganglion, a total of 34 ganglions. The head ganglion was formed by the coalescence of 6 gangliones, it consisted of suprapharyngeal ganglia, peripharyngeal ganglion and suboesophageal ganglion. The ventral nerve included 21 ganglions, each ganglion sent two pairs of nerve. The caudal ganglion was formed by the coalescence of 7 ganglions and in the inside of the posterior sucker. Ganglion from the outside to inside were outside tunica layer, ganglion cell layer, inner tunica layer layer, ganglion fiber capsule. The outside and inner tunica layer were single circular muscles, ganglion cell layer was made of nerve cell, ganglion fiber capsule was intertwined by nerve fiber, the nerve fiber that somatic ganglion sent out was from ganglion fiber capsule. The nephridium existed in pairs, a total of 17 pairs, and located in both sides of the coelom tube. The nephridium was composed of glandular portion and trachlea portion, there was a department in the central of glandular portion, the cells around together formed a channel of trachlea portion. The circulation function of W. pigra is realized by the coelomic sinus, the coelomic sinus was composed of two side longitudinal sinus and branch of lateral sinus. Lateral sinus was irregular in shape, and the wall was thin and consisted of three layers of film. W. pigra had 5 pairs of eyespots, the eyespots in the back of segment of Ⅰ-Ⅳ and arranged into arc. The eyespot was composed of many sensory cells and a pigment cup.(5)It was discovered during the observation of embryonic development that the cocoon was oval and from the outside to inside was composed of three layers of W. pigra. The outer layer was honeycomb and muddy colour, and the shape and texture as the honeycomb. The middle layer was gelatinous and olive green. The internal was protein liquid and the fertilized eggs suspended therein.The fertilized eggs of W. pigra enter 2-cell stage needed about 3h, 4-cell stage needed about 8h, 8-cell stage needed about 12 h and multi-cell stage needed about 1 day after egg cocoons were laid. The blastula stage was observed about 3 days and gastrula stage appeared about 5 days, and larvae hatched about 28 days.Compared with existing literature, this study detailed display gross anatomy structure and histology structure of W. pigra use intuitive and clear picture, to enrich the basic data in morphology study. Secondly, the study detailed showed the embryo development process of W. pigra, to fill the gaps in their embryonic development research. |
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