Hashimoto K, Tamura K, Otani H, Tanaka O
Department of Surgery, Shimane Medical University, Izumo, Japan.
Anat Embryol (Berl). 1995 Dec;192(6):497-505. doi: 10.1007/BF00187180.
To elucidate the role of glycogen in the epithelium of developing digestive organs, we investigated the appearance of glycogen and glycogen phosphorylase (GP) in these organs. We studied 64 externally normal human embryos at Carnegie stages 13-23 (5.1-28.0 mm in crown-rump length, 4-8 weeks of gestation) by histocytochemical staining for glycogen and immunohistochemical staining with antibodies against two isoenzymes of GP: brain-type (BGP) and muscle-brain-type (MBGP) GP. At stage 13, glycogen appeared in the epithelium of the digestive tract and the parenchyma of the pancreas. As development advanced, glycogen granules increased in number and size in these tissues, and they became evenly distributed in the epithelium of the digestive tract as either single particles or aggregates, as deduced by electron microscopy at late embryonic stages. Immunoreactivity specific both for BGP and for MBGP was detected in the digestive tract and the pancreas from stage 13. As development advanced, both BGP- and MBGP-immunoreactive cells increased in number and in immunoreactivity, and the number of MBGP-immunoreactive cells became larger than that of BGP-immunoreactive cells. By contrast, in hepatic cells, which serve as a major storage site for glycogen in adults, glycogen was detected only from stage 20, in smaller amounts, without formation of aggregates, and no immunoreactivity specific for BGP or MBGP was apparent throughout the embryonic stages examined. Thus, in the epithelium of the digestive tract and the parenchyma of the pancreas, but not in hepatic cells, the appearance and localization of GP coincided almost exactly with that of glycogen. These observations suggest that glycogen in the epithelium of the digestive tract and the parenchyma of the pancreas has not only been synthesized but also degraded from an early embryonic period and may, thus, be related to active cellular metabolism that is specific for embryonic development, including proliferation of the epithelium and interactions between epithelium and mesenchyme.
为阐明糖原在发育中消化器官上皮中的作用，我们研究了这些器官中糖原和糖原磷酸化酶（GP）的出现情况。我们通过糖原的组织化学染色以及针对GP的两种同工酶：脑型（BGP）和肌脑型（MBGP）GP的抗体进行免疫组织化学染色，研究了64个处于卡内基分期13 - 23期（冠臀长5.1 - 28.0毫米，妊娠4 - 8周）的外观正常的人类胚胎。在第13期，糖原出现在消化道上皮和胰腺实质中。随着发育推进，这些组织中的糖原颗粒数量和大小增加，并且在胚胎后期通过电子显微镜推断，它们以单个颗粒或聚集体的形式均匀分布在消化道上皮中。从第13期开始，在消化道和胰腺中检测到对BGP和MBGP均具有特异性的免疫反应性。随着发育推进，BGP和MBGP免疫反应性细胞的数量和免疫反应性均增加，并且MBGP免疫反应性细胞的数量变得比BGP免疫反应性细胞的数量更多。相比之下，在成体中作为糖原主要储存部位的肝细胞中，直到第20期才检测到糖原，且含量较少，没有形成聚集体，并且在所检查的整个胚胎阶段均未出现对BGP或MBGP具有特异性的免疫反应性。因此，在消化道上皮和胰腺实质中，而不是在肝细胞中，GP的出现和定位几乎与糖原完全一致。这些观察结果表明，消化道上皮和胰腺实质中的糖原不仅从胚胎早期就已合成，而且也已降解，因此可能与特定于胚胎发育的活跃细胞代谢有关，包括上皮细胞增殖以及上皮与间充质之间的相互作用。
