Dicyemid mesozoans usually consist of 10 to 40 cells. They are characterized by 2 distinct embryos, vermiform and infusoriform, that develop within the axial cell of the adult. The means of escape of each embryo from the parent body was studied in Dicyema japonicum and Dicyema misakiense, parasites of Octopus sinensis. There were no differences in means of escape between species or embryo type, apparently due to morphological constraints whereby the parents (nematogen or rhombogen) share a similar body organization. Escapes were effected through the gap between adjacent peripheral cells of the adult, rupturing the axial cell membrane and the membrane that envelopes the embryo. After the embryo escaped, the path was closed by the enveloping membrane left behind by the embryo. Vermiform embryos can escape from any region of the body, although more embryos were observed to escape from anterior regions than from posterior regions. Infusoriform embryos escaped from both anterior and posterior regions in the axial cell, with more embryos observed to escape from the posterior regions. The different escape regions for the 2 types of embryo are presumably related to the adult body plan lacking a genital opening, so each different type of embryo has its appropriate site of escape.

双胞中生动物通常由 10 至 40 个细胞组成。它们的特征是有 2 个不同的胚胎：蠕虫状和纺锤状，在成体的轴细胞内发育。对中华章鱼的寄生物日本双囊藻（Dicyema japonicum）和三崎双囊藻（Dicyema misakiense）中每个胚胎逃离母体的方式进行了研究。物种或胚胎类型之间的逃逸方式没有差异，这显然是由于父母（线虫或菱形）具有相似的身体组织的形态限制。逃逸是通过成体相邻外周细胞之间的间隙实现的，破坏轴向细胞膜和包裹胚胎的膜。胚胎逃脱后，该路径被胚胎留下的包膜封闭。蠕虫状胚胎可以从身体的任何区域逃脱，尽管观察到从前部区域逃脱的胚胎多于从后部区域逃脱的胚胎。纺锤状胚胎从轴细胞的前部和后部区域逸出，观察到更多胚胎从后部区域逸出。这两种胚胎的不同逃逸区域可能与缺乏生殖器开口的成人身体结构有关，因此每种不同类型的胚胎都有其适当的逃逸部位。