Kiarner Iu K
Arkh Anat Gistol Embriol. 1980 Dec;79(12):36-47.
The avian primitive (Hensen's) knot is the main center of invagination and final determination of endodermal and mesodermal cells at gastrulation. At stages when the primitive streak is lengthening, cells in the primitive knot have the widest morphogenetic potencies and an outstanding ability for neural induction among other parts of the blastoderm. This labile state of the cells is characterized cytologically by an increased catabolism, expressed as an intensified decomposition of the intracellular yolk and increased autophagocytosis. In some places, the partly digested yolk is excreted from the cells and the marker-enzyme of lysosomes--acidic phosphotase--appears in the intercellular space. Some cells perish, and their debris are absorbed by neighbouring cells. The length of the intercellular contact is decreasing. Thus, the period of cell determination is characterized cytologically as a critical period, after P.G. Svetlov, with high injury and decreased regulatory activity. Individualization of the germ layers proves to be the beginning of a new developmental phase and at the cellular level it possesses some signs of transdifferentiation.
鸟类原结（亨森结）是原肠胚形成过程中内胚层和中胚层细胞内陷和最终确定的主要中心。在原条延长的阶段，原结中的细胞具有最广泛的形态发生潜能，并且在胚盘的其他部分中具有突出的神经诱导能力。细胞的这种不稳定状态在细胞学上的特征是分解代谢增加，表现为细胞内卵黄的强化分解和自噬作用增强。在某些部位，部分消化的卵黄从细胞中排出，溶酶体的标记酶——酸性磷酸酶——出现在细胞间隙中。一些细胞死亡，其碎片被相邻细胞吸收。细胞间接触的长度在减小。因此，细胞确定期在细胞学上被表征为一个关键时期，按照P.G. 斯韦特洛夫的说法，这个时期具有高损伤性和降低的调节活性。胚层的个体化被证明是一个新发育阶段的开始，并且在细胞水平上它具有一些转分化的迹象。
