Karam S M
Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait.
Nutrition. 1995 Sep-Oct;11(5 Suppl):607-13.
It is believed that stomach neoplasia represents the end result of a multistep journey that starts with derangement of the cellular proliferation and commitment program of the epithelium. The epithelium is normally made up of a single layer of cells that invaginates to form numerous short pits continuous with long tubular glands divisible into isthmus, neck, and base regions. Three main cell lineages populate these pit-gland units: 1) mucus-secreting pit, 2) pepsinogen-secreting zymogenic, and 3) acid-secreting parietal cell lineages. The immature cells of the unit are located in the isthmus region; they include undifferentiated stem cells that undergo frequent asymmetric mitosis to reproduce themselves and give rise to two partially committed precursors: 1) prepit-cell precursors, which become prepit cells in the isthmus and then migrate outward into the pit and mature into pit cells, and 2) preneck cell precursors, which become preneck cells in the isthmus and then migrate inward to the neck region and transform into neck cells. The latter continue their inward migration and eventually reach the base region where they gradually change their phenotype through a prezymogenic step to become zymogenic cells. The stem cells, as well as the prepit and preneck cell precursors, share in the production of preparietal cells that, in the isthmus, mature into parietal cells and then migrate outward into the pit or inward into the neck and base. The stem cells also give rise to preenteroendocrine and precaveolated cells. These become, respectively, enteroendocrine and caveolated cells that proceed to follow the bidirectional migratory route of parietal cells. The production of rare nonproliferating preparietal cells is enhanced after blocking the secretory activity of their mature forms by continuous infusion of the histamine H2-receptor antagonist, ranitidine, for 42 h. Thus, the presence of active mature parietal cells is necessary to maintain the normal cellular proliferation and commitment program in the gastric epithelium.
人们认为胃肿瘤是一个多步骤过程的最终结果，这个过程始于上皮细胞增殖和分化程序的紊乱。上皮通常由单层细胞组成，这些细胞内陷形成许多短凹，与可分为峡部、颈部和底部区域的长管状腺体相连。这些凹-腺单位中有三种主要的细胞谱系：1）分泌黏液的凹细胞，2）分泌胃蛋白酶原的泌酸腺细胞，以及3）分泌胃酸的壁细胞谱系。该单位的未成熟细胞位于峡部区域；它们包括未分化的干细胞，这些干细胞频繁进行不对称有丝分裂以自我复制，并产生两种部分分化的前体细胞：1）前凹细胞前体，它们在峡部成为前凹细胞，然后向外迁移到凹部并成熟为凹细胞，以及2）前颈部细胞前体，它们在峡部成为前颈部细胞，然后向内迁移到颈部区域并转变为颈部细胞。后者继续向内迁移，最终到达底部区域，在那里它们通过一个前泌酸腺细胞阶段逐渐改变其表型，成为泌酸腺细胞。干细胞以及前凹和前颈部细胞前体共同产生前壁细胞，这些前壁细胞在峡部成熟为壁细胞，然后向外迁移到凹部或向内迁移到颈部和底部。干细胞还产生前肠内分泌细胞和前空泡化细胞。这些细胞分别成为肠内分泌细胞和空泡化细胞，并沿着壁细胞的双向迁移途径发展。通过连续输注组胺H2受体拮抗剂雷尼替丁42小时来阻断其成熟形式的分泌活性后，罕见的非增殖性前壁细胞的产生会增加。因此，活跃的成熟壁细胞的存在对于维持胃上皮中的正常细胞增殖和分化程序是必要的。
