Karam S M, Leblond C P
Department of Anatomy, McGill University, Montreal, Quebec, Canada.
Anat Rec. 1993 Jun;236(2):280-96. doi: 10.1002/ar.1092360203.
The pit cells (or surface mucous cells) present along pit walls and gastric surface have been investigated by electron microscopy and radioautography after a pulse or continuous infusion of 3H-thymidine. For these studies, the pit region has been subdivided into four segments: three of equal length along the pit wall, respectively named low pit, mid pit and high pit, and a last one at the surface named pit top. The pit region includes an average of 37 pit cells, characterized by dense mucous granules accumulated along the apical membrane in an organelle-free zone referred to as ectoplasm. Continuous 3H-thymidine infusion reveals that pit cells come from pre-pit cells, which are believed to arise in the isthmus region from the undifferentiated granule-free cells through a pre-pit cell precursor stage. The pre-pit cells, characterized by the presence of a few mucous secretory granules scattered in the cytoplasm, migrate outward (i.e., in the direction of the gastric lumen). When the secretory granules line up along the apical membrane in the ectoplasm, the pre-pit cell becomes pit cell. It is estimated that 87% of pit cells differentiate from pre-pit cells, while the remaining 13% come from their own mitoses. Observations at successive times after a 3H-thymidine pulse demonstrate that pit cells, like pre-pit cells, migrate toward the gastric surface where they are eventually lost. The continuous 3H-thymidine infusion results indicate that this migration takes 3.1 days on the average. Cells spend almost a day in each pit wall segment. In the low pit segment, cells produce more and larger mucous secretory granules than do pre-pit cells. In the mid and high pit segments, the number and size of the granules generally keeps on increasing, thus indicating that mucous differentiation is progressing. The secretory granules arising in the Golgi apparatus of pit wall cells are mostly spherical; they retain this shape during the few minutes taken to cross the cytoplasm and enter the apical ectoplasm. They spend about an hour in the ectoplasm, where they change to an ovoid shape as they approach the apical membrane to finally release their content by exocytosis. The mucous differentiation along the pit wall is associated with a progressive decline in the organelles: nucleoli and mitochondria decrease in size while the amount of free ribosomes diminishes. When pit cells reach the free surface, they produce fewer, smaller secretory granules and at a lower rate than in mid and high pit.(ABSTRACT TRUNCATED AT 400 WORDS)
在脉冲或持续注入³H-胸腺嘧啶核苷后，通过电子显微镜和放射自显影术对沿胃小凹壁和胃表面分布的胃小凹细胞（即表面黏液细胞）进行了研究。在这些研究中，胃小凹区域被细分为四个部分：沿胃小凹壁有三个长度相等的部分，分别称为低位小凹、中位小凹和高位小凹，最后一个在表面的部分称为小凹顶部。胃小凹区域平均包含37个胃小凹细胞，其特征是在无细胞器区（称为外质）沿着顶膜积累了密集的黏液颗粒。持续注入³H-胸腺嘧啶核苷显示，胃小凹细胞来自前胃小凹细胞，据信前胃小凹细胞是由峡部区域未分化的无颗粒细胞通过前胃小凹细胞前体阶段产生的。前胃小凹细胞的特征是细胞质中散布着一些黏液分泌颗粒，它们向外迁移（即朝着胃腔方向）。当分泌颗粒沿着外质中的顶膜排列时，前胃小凹细胞就变成了胃小凹细胞。据估计，87%的胃小凹细胞从前胃小凹细胞分化而来，其余13%来自它们自身的有丝分裂。在³H-胸腺嘧啶核苷脉冲后的连续时间观察表明，胃小凹细胞与前胃小凹细胞一样，朝着胃表面迁移，最终在那里消失。持续注入³H-胸腺嘧啶核苷的结果表明，这种迁移平均需要3.1天。细胞在每个胃小凹壁部分停留近一天。在低位小凹部分，细胞产生的黏液分泌颗粒比前胃小凹细胞更多、更大。在中位和高位小凹部分，颗粒的数量和大小通常持续增加，这表明黏液分化在进行。胃小凹壁细胞的高尔基体中产生的分泌颗粒大多是球形的；在穿过细胞质并进入顶外质的几分钟内，它们保持这种形状。它们在外质中停留约一小时，在接近顶膜时变成卵形，最终通过胞吐作用释放其内容物。沿胃小凹壁的黏液分化与细胞器的逐渐减少有关：核仁和线粒体大小减小而游离核糖体数量减少。当胃小凹细胞到达游离表面时，它们产生的分泌颗粒更少、更小，且速率低于中位和高位小凹。（摘要截选至400字）
