Weisblat D A, Kim S Y, Stent G S
Dev Biol. 1984 Jul;104(1):65-85. doi: 10.1016/0012-1606(84)90037-x.
To ascertain the embryonic origins of the cells in various tissues of the leech Helobdella triserialis, horseradish peroxidase (HRP) was injected as a cell lineage tracer into all identified blastomeres of the early embryo in turn, except for a few of the micromeres, and the resulting distribution of HRP-labeled cells was then examined in the late embryo. In this way it was found that in every body segment a topographically characteristic set of neurons in the ganglion and body wall and a characteristic territory of the epidermis is derived from each of the four paired ectodermal teloblasts N, O/P, O/P, and Q, whereas the muscles, nephridia, and connective tissue, as well as a few presumptive neurons in each segmental ganglion, are derived from the paired mesodermal teloblast, M. Each topographically characteristic, segmentally iterated set of neurons descended from a given teloblast is designated as a kinship group. However, the prostomial (nonsegmental) epidermis and the neurons of the supraesophageal ganglion were found to be derived from the a, b, c, and d micromere quartet to which the A, B, C, and D blastomeres give rise at the dorsal pole of the embryo. The superficial epithelium of the provisional integument, which covers the surface of the embryo midway through development and is sloughed off at the time of body closure, was found to be derived from the a, b, c, and d micromere quartet, as well as from other micromeres produced in the course of teloblast formation. The contractile fibers of the provisional integument were found to be derived from the paired M teloblast. These results demonstrate that development of the leech embryo proceeds according to a highly stereotyped pattern, in the sense that a particular identifiable blastomere of the early embryo regularly gives rise to a particular set of cells of the adult (or provisional embryonic) tissues.
为确定三带水蛭（Helobdella triserialis）各组织中细胞的胚胎起源，将辣根过氧化物酶（HRP）作为细胞谱系示踪剂依次注射到早期胚胎的所有已鉴定的卵裂球中，但少数小卵裂球除外，然后在晚期胚胎中检查HRP标记细胞的分布情况。通过这种方式发现，在每个体节中，神经节和体壁中一组具有拓扑特征的神经元以及表皮的一个特征区域分别源自四对外胚层端细胞N、O/P、O/P和Q中的每一个，而肌肉、肾管和结缔组织，以及每个节段神经节中的一些推定神经元则源自成对的中胚层端细胞M。每个源自给定端细胞的具有拓扑特征、节段重复的神经元组被指定为一个亲属组。然而，发现口前叶（非节段性）表皮和食管上神经节的神经元源自胚胎背极处A、B、C和D卵裂球产生的a、b、c和d小卵裂球四重体。临时体被的表面上皮在发育中期覆盖胚胎表面，并在身体闭合时脱落，发现其源自a、b、c和d小卵裂球四重体，以及在端细胞形成过程中产生的其他小卵裂球。发现临时体被的收缩纤维源自成对的M端细胞。这些结果表明，水蛭胚胎的发育按照高度定型的模式进行，即早期胚胎中特定可识别的卵裂球通常会产生成体（或临时胚胎）组织中的特定一组细胞。
