title: Ultrastructure and electron immunocytochemistry of insulin-producing B-cell tumors from transgenic mice: comparison with counterpart human tumors.
abstract: This paper reports on an ultrastructural and electron-microscopic immunocytochemical study of pancreatic B cells from normal mice, pancreatic B cells and derivative tumors from transgenic mice, and tissue from human pancreatic B-cell tumors. In normal and neoplastic B cells from both species, typical immature and mature beta-granules (with spherical cores of variable density) were observed, whereas typical beta-granules with a crystalloid core were only present in human B cells (normal and tumor). A small number of atypical granules were found in distinct neoplastic cells which contained no typical beta-granules. The atypical granules were smaller (100-200 nm diameter) than typical beta-granules (250-450 nm diameter) seen in other cells. Immunoreactivity for proinsulin was localized only to immature granules, whereas insulin and C-peptide immunoreactivities were demonstrated in atypical, immature, and mature granules. In transgenic mouse and human B-cell tumors, insulin immunoreactivity was consistently weaker than the immunostaining for C-peptide. An intragranular, topographic segregation of immunoreactive C-peptide was observed in a population of transgenic tumor cells. Our results showed similarities in antigenic distribution and only slight differences in morphology between human and mouse B cells. Therefore, the transgenic mouse system may prove to be an effective model for studying mammalian B-cell tumorigenesis.
authors.affiliation: Department of Histochemistry, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Holm
authors.forename: I M
authors.initials: IM
authors.lastname: Varndell
authors.forename: R F
authors.initials: RF
authors.lastname: Power
authors.forename: A E
authors.initials: AE
authors.lastname: Bishop
authors.forename: O D
authors.initials: OD
authors.lastname: Madsen
authors.forename: S
authors.initials: S
authors.lastname: Alpert
authors.forename: D
authors.initials: D
authors.lastname: Hanahan
authors.forename: J M
authors.initials: JM
authors.lastname: Polak
mesh_terms: D007516:Adenoma, Islet Cell / Q000032:analysis*; D000818:Animals; D002096:C-Peptide / Q000032:analysis*; D003594:Cytoplasmic Granules / Q000032:analysis* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000032:analysis*; D007340:Insulinoma / Q000032:analysis* / Q000235:genetics / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic / Q000378:metabolism*; D008854:Microscopy, Electron; D010190:Pancreatic Neoplasms / Q000032:analysis* / Q000235:genetics / Q000648:ultrastructure
chemical_list: D002096:C-Peptide; D007328:Insulin