蓬莱玉参早期发育的形态学观察

The Morphological Observation on the Early Development of Penglai Milky Cucumber(Apostichopus japonicus)

本研究对仿刺参（Apostichopus japonicus）的一个特殊品系蓬莱玉参产卵、受精及胚胎和幼体发育过程进行显微观察，并与普通仿刺参进行比较。在19～21℃水温下，蓬莱玉参受精卵分别在受精12min和24min后释放第一、二极体，1h后卵裂成2细胞期，之后每30min左右完成一次卵裂，6h后进入囊胚期，19h后发育成原肠胚；40h后进入耳状幼体阶段，在其后侧臂的一端出现一个不规则形的石灰质骨片，并发现其位置与水体腔处于同一侧这一规律；5d和8d后发育为中耳状幼体和大耳状幼体，10d后变态发育为樽形幼体，骨片由不规则状发育为齿轮状，并出现第二个石灰质骨片；12d后发育为五触手，14d后发育成稚参，40d后发育为幼参。蓬莱玉参胚胎和幼体发育时序与当前己报道的仿刺参无显著差异，但从幼参开始蓬莱玉参通体始终为白色，而普通仿刺参在45日龄时体表局部出现色素，疣足处较为明显，60日龄幼体一半以上全身布满色素。蓬莱玉参因通体纯白色而受到了众多养殖企业和研究领域的关注，本文的结果为其今后的研究奠定了可靠的理论基础。

Penglai Milky Cucumber （Apostichopus japonicus） is a new strain in Sea Cucumber ranching and aquaculture. In this paper, for a better understanding and identifying the similarities and differences between Penglai Milky Cucumber and Common Sea Cucumber, and for evaluating the potential use and increasing the natural populations of Penglai Milky Cucumber, the embryonic and larval development was observed under the light microscope, and the time course of embryonic and larval development was confirmed. At the water temperature of 19 - 21 ℃ and salinity of 31, the first meiosis and second meiosis completed at 12 minutes and 24 minutes respectively after insemination （Fig. 2c, d）; the eggs developed to 2 cells at 1 hour, completed a cleavage every 30 minutes, developed to the blastula at 6 hours, and to the gastrula at 19 hours. The fertilized eggs grew into early auricularia at 40 hours after fertilization （Fig. 3a）, and then into the mid-anricularia and auricularia at 5 days and 8 days, respectively. In addition, an irregularly shaped calcareous bone appeared at the end of posterior arm of the larva, and the water cavity was observed on the same side （Fig. 4a）. The larvae underwent metamorphosis to become doliolaria at 10 days, when the irregular bone developed into gear bone and the second calcareous bone appeared. The larvae developed to pentactula at 12 days, and to juvenile Sea Cucumber at 14 days. There was no significant difference in the developmental time course between Penglai Milky Cucumber and Common Sea Cucumber （Table 1）. Penglai Milky Cucumber was in pure white on the whole body after juvenile stage. However, the Common Sea Cucumber showed some pigment at surface in 45 days, especially at the bottom of parapodum （Fig. 5b）, and more than half of the juveniles were full of pigment at 60 days. In conclusion, Penglai Milky Cucumber is different from Common Sea Cucumber （Selenka） as indicated by its white body, which makes it attractive to. aquaculture companies and institutions, and the data of this study will provide reliable theoretical basis for Penglai Milky Cucumber＇s research in the future.