Okubo Nami, Motokawa Tatsuo
Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Kanagawa, Japan.
Zoolog Sci. 2007 Dec;24(12):1169-77. doi: 10.2108/zsj.24.1169.
Embryogenesis in the reef building corals Acropora intermedia, A. solitaryensis, A. hyacinthus, A. digitifera, and A. tenuis was studied in detail at the morphological level, and the relationships among the animal pole, blastopore, and mouth were investigated for the first time in corals. These species showed essentially the same sequence of development. The embryo undergoes spiral-like holoblastic cleavage despite the presence of a dense isolecithal yolk. After the morula stage, the embryo enters the "prawn-chip" stage, which consists of an irregularly shaped cellular bilayer. The embryo begins to roll inward to form the bowl stage; the round shape observed during this stage suggests that it may be the beginning of gastrulation. However, the blastopore closes and the stomodeum (mouth and pharynx) is formed via invagination at a site near the closed blastopore. During the planula stage, a concavity forms in the aboral region in conjunction with numerous spirocysts, suggesting that spirocysts are used to attach to the substrate before the onset of metamorphosis.
在形态学水平上详细研究了造礁珊瑚中间鹿角珊瑚、单枝鹿角珊瑚、风信子鹿角珊瑚、指状鹿角珊瑚和细枝鹿角珊瑚的胚胎发生过程，并首次在珊瑚中研究了动物极、胚孔和口之间的关系。这些物种表现出基本相同的发育序列。尽管存在密集的均黄卵黄，但胚胎仍进行螺旋状全裂。桑葚胚阶段后，胚胎进入“虾片”阶段，该阶段由不规则形状的细胞双层组成。胚胎开始向内卷曲形成碗状阶段；在此阶段观察到的圆形表明这可能是原肠胚形成的开始。然而，胚孔关闭，口凹（口和咽）通过在关闭的胚孔附近的一个部位内陷形成。在浮浪幼虫阶段，在反口区域形成一个凹陷，并伴有大量螺旋囊，这表明螺旋囊在变态开始前用于附着在基质上。
