Cellular differentiation in the embryonic rat pancreas, with special reference to the co-existence of substances immunoreactive to both insulin and glucagon antibodies in the same cells.
We used light and electron microscopy and immunohistochemistry to examine the pancreas primordium in 11- to-20-day-old rat embryos. Cells that were immunoreactive to glucagon-like antibodies (G-like cells) first appeared under light microscopy on day 11, and those immunoreactive to insulin-like antibodies (I-like cells) appeared on day 13. All the I-like cells also reacted to G-like substance antibody. From the 13th to the 17th day of gestation, the G-like cells proliferated rapidly while the I-like cells increased in number very slowly. All the I-like cells continued to react with G-like substance antibody as well. The I-like cells began increasing rapidly on the 18th day and soon occupied about half of the islet-constituting cells. They no longer reacted with G-like substance antibody. Using double-label immunostaining with protein A-colloidal gold, the pancreatic endocrine cells became visible in 15-day-old embryos as large polygonal cells containing numerous secretion granules 180-200 nm in diameter. Some of these cells reacted to both I-like and G-like substance antibodies. These findings show the co-existence of G-like and I-like substances in rat embryo pancreatic endocrine cells between the 13th and 17th days of gestation, after which the I-like cells proliferate rapidly, and undergo definitive differentiation from the G-like cells.
Taki
J
J
Second Department of Internal Medicine, Kobe University School of Medicine, Japan.
Baba
S
S
D000818:Animals; D004622:Embryo, Mammalian; D005934:Glucagon / Q000032:analysis*; D007106:Immune Sera; D007124:Immunoenzyme Techniques; D007328:Insulin / Q000032:analysis*; D007515:Islets of Langerhans / Q000166:cytology / Q000196:embryology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010179:Pancreas / Q000166:cytology / Q000196:embryology*; D051381:Rats; D011919:Rats, Inbred Strains
D007106:Immune Sera; D007328:Insulin; D005934:Glucagon