Zajicek G
H. H. Humphrey Center for Experimental Medicine, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Med Hypotheses. 1995 Oct;45(4):403-7. doi: 10.1016/0306-9877(95)90105-1.
The cell kinetic characteristic of all epithelia is the same. All are analogs of the crypt-villus unit of the gastrointestinal mucosa. Each unit is nourished by at least one determined uncommitted stem cell (DS). When the DS divides, one of its progeny replaces the parent and remains a DS, while the other starts streaming outward. When entering a differentiation pathway it is called a committed stem cell (CS). Cells in the unit differentiate while streaming. Initially they continue multiplying and are called amplifying progenitors (P-cells), then they lose the capacity to synthesize DNA and become non-dividing (quiescent) end cells (Q-cells). All cells except the DS are transitional and short lived (in the crypt they live several days): only the DS is permanent. Since epithelial tissues are cell kinetic analogs of the crypt, it is assumed here that their neoplastic progression is analogous with the adenoma-carcinoma sequence of the crypt. Neoplasia starts when a normal cell is transformed into a neoplastic. If a transitional cell is hit by a carcinogen and transformed into a neoplastic, it soon will be washed out from the system. Only a transformed DS can maintain the neoplastic trait since it never leaves the crypt. Neoplasia is thus a pathology of the DS. There are two differentiation scales in the embryo: global and local. The first starts with the fertilized ovum that divides into stem cells that become more and more determined. Following gastrulation each determined stem cell generates its local progeny of transitional cells that make the tissue units. Determined stem cells are direct descendants of the fertilized ovum, while their transitional progenitors are direct descendants of determined stem cells.
所有上皮组织的细胞动力学特征都是相同的。它们都是胃肠道黏膜隐窝 - 绒毛单位的类似物。每个单位至少由一个定向未分化干细胞（DS）提供营养。当DS分裂时，其后代之一取代亲代并仍为DS，而另一个则开始向外流动。当进入分化途径时，它被称为定向干细胞（CS）。该单位中的细胞在流动过程中发生分化。最初它们继续增殖，被称为扩增祖细胞（P细胞），然后它们失去合成DNA的能力，成为不分裂（静止）的终末细胞（Q细胞）。除DS外的所有细胞都是过渡性的且寿命短暂（在隐窝中存活数天）：只有DS是永久性的。由于上皮组织是隐窝的细胞动力学类似物，在此假设它们的肿瘤进展与隐窝的腺瘤 - 癌序列相似。肿瘤形成始于正常细胞转变为肿瘤细胞。如果一个过渡性细胞受到致癌物影响并转变为肿瘤细胞，它很快就会从系统中被清除。只有转化的DS能够维持肿瘤特征，因为它从不离开隐窝。因此，肿瘤形成是DS的一种病理学表现。胚胎中有两种分化尺度：全局尺度和局部尺度。第一种从受精卵开始，受精卵分裂为越来越定向的干细胞。原肠胚形成后，每个定向干细胞产生其局部的过渡性细胞后代，这些后代构成组织单位。定向干细胞是受精卵的直接后代，而它们的过渡性祖细胞是定向干细胞的直接后代。
