Zahavi N, Reich V, Khaner O
Department of Cell and Animal Biology, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel.
Int J Dev Biol. 1998 Jan;42(1):95-8.
Localized zones of high cell proliferation have been thought to be important in determining several phases of axis formation at early stages of chick development. It was suggested that a developmental center, a center of cellular activity such as proliferation and movement, is located in the posterior half of the area pellucida in the unincubated chick blastoderm. In the work reported here, we have used the bromodeoxyuridine (BrdU) incorporation procedure followed by immunoperoxidase detection to assess the rate of cell proliferation at particular sub-regions of pregastrulating chick blastoderms (stages X-XIII). Examination of whole-mount and histological sections of stages X through XII blastoderms, pulsed with BrdU, showed no distinguishable difference in labeled cells between particular regions of these blastoderms and also that there are no specific zones of high cellular proliferation in either the hypoblast or the epiblast layers of the area pellucida. However, our observations have shown a striking difference in the stage XIII blastoderm, in which a relatively high amount of labeled cells were detected all around the posterior region of the area opaca, the marginal zone, Koller's sickle and the epiblast. The relatively high proportion of cell divisions observed at the posterior end of a stage XIII blastoderm, the blastula stage of the avian embryo, may be associated with the major developmental ability of this region to initiate an embryonic axis. Directional axis formation, therefore, may be attributed to a region of proliferation in the posterior side of a stage XIII blastoderm.
局部高细胞增殖区域被认为在鸡胚发育早期轴形成的几个阶段中起着重要作用。有人提出，在未孵化的鸡胚盘透明区后半部存在一个发育中心，即细胞活动（如增殖和迁移）的中心。在本文报道的研究中，我们采用了溴脱氧尿苷（BrdU）掺入法，随后进行免疫过氧化物酶检测，以评估原肠胚形成前鸡胚盘特定亚区域（X-XIII期）的细胞增殖速率。对用BrdU脉冲处理的X至XII期胚盘的整体标本和组织切片进行检查发现，这些胚盘的特定区域之间标记细胞没有明显差异，并且在透明区的下胚层或上胚层中也没有高细胞增殖的特定区域。然而，我们的观察结果显示，XIII期胚盘存在显著差异，在不透明区的后区域、边缘区、科勒镰刀和上胚层周围检测到相对大量的标记细胞。在鸡胚囊胚期的XIII期胚盘后端观察到相对较高比例的细胞分裂，这可能与该区域启动胚胎轴的主要发育能力有关。因此，定向轴的形成可能归因于XIII期胚盘后侧的增殖区域。
