García-Arrarás J E, Estrada-Rodgers L, Santiago R, Torres I I, Díaz-Miranda L, Torres-Avillán I
Department of Biology, University of Puerto Rico, Río Piedras 00931.
J Exp Zool. 1998 Jul 1;281(4):288-304. doi: 10.1002/(sici)1097-010x(19980701)281:4<288::aid-jez5>3.0.co;2-k.
Echinoderms are the deuterostome group with the most striking capacity to regenerate lost body parts. In particular, members of the class Holothuroidea are able to regenerate most of their internal organs following a typical evisceration process. Such formation of new viscera in an adult organism provides a unique model to study the process of organogenesis. We have studied this process in the sea cucumber Holothuria glabberrima by describing the spatial and temporal pattern of cellular events that occur during intestine regeneration following chemically induced evisceration. Regeneration begins as a thickening of the mesenteries that supported the autotomized organs to the body wall. The mesenterial thickening consists of tissues where most of the cellular populations found in the normal intestine are already present. However, the cell numbers differ, particularly those of hemocytes and amoebocytes, suggesting that some of these cells play an important role in the formation of the solid rod of hypertrophic mesentery that characterizes the intestinal primordia. The appearance of the luminal epithelium, together with the formation of the lumen, occurs during the second week of regeneration by proliferation and extensive migration of cells from the esophagus and cloacal ends into the thickenings. At this stage all tissue layers are present, but it takes an additional week for them to exhibit the proportions typical of the normal organ. Cell division, as determined by BrdU labeling, mainly occurs in the coelomic epithelia of the hypertrophic mesentery and in the regenerating luminal epithelium. Our study provides evidence that the process of new organ formation in holothurians can be described as an intermediate process showing characteristics of both epimorphic and morphallactic phenomena.
棘皮动物是具有最显著再生缺失身体部位能力的后口动物类群。特别是，海参纲的成员在经历典型的排脏过程后能够再生其大部分内脏器官。成年生物体中这种新内脏的形成提供了一个研究器官发生过程的独特模型。我们通过描述化学诱导排脏后肠道再生过程中发生的细胞事件的时空模式，对光裸刺参的这一过程进行了研究。再生始于肠系膜增厚，肠系膜将自切器官支撑到体壁。肠系膜增厚由正常肠道中发现的大多数细胞群体已经存在的组织组成。然而，细胞数量不同，尤其是血细胞和变形细胞，这表明这些细胞中的一些在形成肥厚肠系膜的实心杆（即肠道原基的特征）中起重要作用。腔上皮的出现以及腔的形成，在再生的第二周通过细胞从食管和泄殖腔末端增殖并大量迁移到增厚部位而发生。在这个阶段，所有组织层都已存在，但它们还需要额外一周时间才能呈现出正常器官典型的比例。通过BrdU标记确定，细胞分裂主要发生在肥厚肠系膜的体腔上皮和再生的腔上皮中。我们的研究提供了证据，表明海参新器官形成的过程可以被描述为一个中间过程，兼具形态发生和形态建成现象的特征。
