中国对虾循环系统的发生

The genesis of the circulatory system of Penaeus chinensis

采用组织学方法 ,研究了中国对虾循环系统的发生过程 ,在无节幼体第 3期 ,起源于头胸甲皱褶部位的腹侧中胚层细胞通过增殖向背面迁移 ,在中肠的背面形成一中胚层板 ,此板两侧向背面上卷、合拢而成心脏 ;与此同时 ,该中胚层板两侧周围的中胚层细胞向两侧迁移 ,与体壁接触形成围心腔 ;心孔出现在无节幼体第 5期 ,是由该处的心壁细胞直接内陷形成 ;心脏的形态结构随着幼体的发育而不断完善 ,至蚤状幼体第 1期以后 ,组成心壁的细胞分化为单层的心肌细胞 ,随后其外包被一层由结缔组织细胞形成的心外膜 ;至仔虾期 ,心脏的外形和结构已与成虾的相似 ;背腹动脉发生的方式与时间和心脏的相同 ;中背动脉的发生包括两部分 :心脏近端的中背动脉由心脏前端延伸而成 ,心脏远端的中背动脉则由幼体前端背部中胚层细胞形成 ;血细胞最早出现在无节幼体第 1期。

The development process of the circulatory system of Penaeus chinensis has been studied with tissue method.At the third stage of nauplius, originating from the part of carapace rudiment,the mesoderm cells of each side of ventral-lateral part of the larva divide quickly and extend towards back to form the heart rudiment cells.Then some of them migrate medially to form a mesodermal plate above the back of the mid-gut.After that,the plate curls towards back to form the heart.Meanwhile,the others extend outwardly to make contact with each side of lateral part and form the pericardial cavities.At the fifth stage of nauplius,the wall of heart slits inward directly to form the ostia.The shape and the structure of heart improve with the development of the larvae.After the first stage of zoaea,the cells of heart wall develop into myocardial cells.Subsequently,one thin layer of adventitia formed by the connective tissue cells encloses the myocardium.At the post larva stage,the appearance and the tissue structure of heart are similar to those of adult.The measure and time of development of dorasl abdominal artery are similar to those of heart.The formation of median dorsal artery includes two parts:one part near heart is extended by the heard of heart;another part far away from heart is formed by mesodermal cells in front of nauplius back;hemocytes are observed at the first nauplius.