Helmark Sandra, Garm Anders
Marine Biological Section, University of Copenhagen, Copenhagen, Denmark.
J Morphol. 2019 Oct;280(10):1530-1536. doi: 10.1002/jmor.21046. Epub 2019 Jul 23.
Cubozoans have a complex lifecycle in many ways similar to the scyphozoan lifecycle. The sexual reproduction within cubozoans varies between species with one clade having copulation and internal fertilization and the release of planula larvae. This cubozoan clade, the family Tripedaliidae, includes three species, Copula sivickisi, Tripedalia cystophora, and Tripedalia binata. In a recent study, it was suggested that in C. sivickisi cnidocytes play a new and important role during the sexual reproduction. Male derived cnidocytes anchor sperm packages to the female gonads and female derived cnidocytes protect the externalized embryo strand. Here, we have examined the gonads and gametes of T. cystophora and our results reveal that the male produced spermatozeugmata have a high number of isorhiza type cnidocytes, which are transferred along with the sperm during copulation. This adds further support to our hypothesis that they are important for sperm anchorage. The female gonads are lacking cnidocytes all together showing that cnidocyte production is not just a default state of the epithelium in these animals.
立方水母在许多方面具有复杂的生命周期，这与钵水母的生命周期相似。立方水母的有性生殖因物种而异，其中一个进化枝进行交配、体内受精并释放浮浪幼虫。这个立方水母进化枝，即三腕水母科，包括三种物种，西氏交配水母、多手多臂水母和二臂多手多臂水母。在最近的一项研究中，有人提出在西氏交配水母中，刺细胞在有性生殖过程中发挥着新的重要作用。雄性来源的刺细胞将精子包固定在雌性生殖腺上，而雌性来源的刺细胞保护外露的胚胎链。在这里，我们研究了多手多臂水母的生殖腺和配子，我们的结果表明，雄性产生的精子包有大量等刺型刺细胞，这些刺细胞在交配过程中与精子一起转移。这进一步支持了我们的假设，即它们对精子固定很重要。雌性生殖腺完全没有刺细胞，这表明刺细胞的产生并非这些动物上皮细胞的默认状态。
