title: Histidyl-proline diketopiperazine (His-Pro DKP) immunoreactivity is present in the glucagon-containing cells of the human fetal pancreas.
abstract: Histidyl-proline diketopiperazine (His-Pro DKP) cells in the pancreas of human fetuses aged between 12 and 19 wk were localized by the indirect antibody-enzyme method on semithin sections. To study their fine structure, two techniques were used: a superimposition technique consisting of comparison of the same cells in semithin and electron microscopic preparations, and an immunocytochemical technique on ultrathin sections using the unlabeled antibody peroxidase-antiperoxidase method. Our results show that (a) the same cells are positive for both His-Pro DKP and glucagon/glicentin, (b) His-Pro DKP immunoreactive cells possess extremely electron-opaque secretory granules, implying that these cells correspond to the A cells, and (c) His-Pro DKP immunoreactivity is found over the secretory granules. We hypothesize that the two peptides His-Pro DKP and thyrotropin-releasing hormone (TRH) have independent origins, since TRH is found in the B cells.
mesh_terms: D003594:Cytoplasmic Granules / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D005934:Glucagon / Q000378:metabolism*; D006651:Histocytochemistry; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008854:Microscopy, Electron; D010179:Pancreas / Q000196:embryology* / Q000378:metabolism; D010456:Peptides, Cyclic / Q000378:metabolism*; D010879:Piperazines / Q000378:metabolism*; D052336:Proglucagon; D011498:Protein Precursors / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D010456:Peptides, Cyclic; D010879:Piperazines; D011498:Protein Precursors; D052336:Proglucagon; D013973:Thyrotropin-Releasing Hormone; D005934:Glucagon; C015924:histidyl-proline diketopiperazine