Histocytochemical and immunohistochemical studies related to the role of glycogen in human developing digestive organs

Abstract

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.

Occlusion and subsequent re-canalization in early duodenal development of human embryos: integrated organogenesis and histogenesis through a possible epithelial-mesenchymal interaction

“…They belong to the Kyoto Collection of Human Embryos (Nishimura et al 1968;Nishimura 1975;Nishimura 1983;Tanaka et al 1987;Otani and Tanaka 1988;Tanaka 1991;Otani et al 1992Otani et al , 1993Hashimoto et al 1995;Nishikori et al 1999;Nakatsu et al 2000, detailed description of the collection therein). External features of these embryos were observed under a binocular dissection microscope and their developmental stages were determined according to the reported criteria (O'Rahilly 1972).…”

“…We and others have suggested that these changes are related to epithelial differentiation in the gastrointestinal tube during early embryonic development (Hashimoto et al 1995;Mathan et al 1976;Toyota et al 1989). The present samples at stages 22 and 23 contained granules in the basal cytoplasm of some epithelial cells, indicating a differentiation of endocrine function.…”

Apoptosis during inner ear development in human and mouse embryos: an analysis by computer-assisted three-dimensional reconstruction

“…All were obtained through collaboration with obstetricians in Japan as reported (Nishimura 1975;Otani et al 1993;Hashimoto et al 1995;Tanaka et al 1995) and belong to the Congenital Anomaly Research Center, Kyoto University, Faculty of Medicine. The external features of these embryos were examined under a binocular dissecting microscope, and the developmental stage of each embryo was determined as described by O'Rahilly (1972).…”

Global gene expression profiling and histochemical analysis of the developing human fetal pancreas

“…Extrapolation from our knowledge of transcriptional regulation of rodent pancreatic development to the human is thus difficult and needs to be evaluated in the context of morphological events. There are also a number of discrepancies in published accounts of endocrine cell development in the human pancreas regarding whether early endocrine cells produce multiple hormones and at which stage the fetal cells are developmentally or functionally 'mature' [2,[4][5][6][7][8][9].…”