Bode P M, Awad T A, Koizumi O, Nakashima Y, Grimmelikhuijzen C J, Bode H R
Department of Developmental and Cell Biology, University of California, Irvine 92717.
Development. 1988 Jan;102(1):223-35. doi: 10.1242/dev.102.1.223.
The head of a hydra is composed of two parts, a domed hypostome with a mouth at the top and a ring of tentacles below. When animals are decapitated a new head regenerates. During the process of regeneration the apical tip passes through a transient stage in which it exhibits tentacle-like characteristics before becoming a hypostome. This was determined from markers which appeared before morphogenesis took place. The first was a monoclonal antibody, TS-19, that specifically binds to the ectodermal epithelial cells of the tentacles. The second was an antiserum against the peptide Arg-Phe-amide (RFamide), which in the head of hydra is specific to the sensory cells of the hypostomal apex and the ganglion cells of the lower hypostome and tentacles. The TS-19 expression and the ganglion cells with RFamide-like immunoreactivity (RLI) arose first at the apex and spread radially. Once the tentacles began evaginating in a ring, both the TS-19 antigen and RLI+ ganglion cells gradually disappeared from the presumptive hypostome area and RLI+ sensory cells appeared at the apex. By tracking tissue movements during morphogenesis it became clear that the apical cap, in which these changes took place, did not undergo tissue turnover. The implications of this tentacle-like stage for patterning the two-part head are discussed.
水螅的头部由两部分组成，顶部是带有口的圆顶状口盘，下方是一圈触手。当水螅被斩首后，会再生出一个新的头部。在再生过程中，顶端会经历一个短暂阶段，在成为口盘之前呈现出触手样特征。这是通过在形态发生之前出现的标记物确定的。第一个标记物是单克隆抗体TS-19，它特异性结合触手的外胚层上皮细胞。第二个是针对肽Arg-Phe-酰胺（RFamide）的抗血清，在水螅头部，该肽对口盘顶端的感觉细胞以及下部口盘和触手的神经节细胞具有特异性。TS-19表达和具有RFamide样免疫反应性（RLI）的神经节细胞首先出现在顶端并呈放射状扩散。一旦触手开始呈环状外翻，TS-19抗原和RLI+神经节细胞就会逐渐从假定的口盘区域消失，而RLI+感觉细胞则出现在顶端。通过追踪形态发生过程中的组织运动，很明显发生这些变化的顶端帽没有经历组织更新。本文讨论了这个触手样阶段对两部分头部模式形成的影响。
