RESUMO
Schwann cells forming peri-insular glial sheath of the pancreatic islets in some mammals can be involved in the pathogenesis of diabetes mellitus. Human pancreatic cells contain small elongated or oval cells of unknown origin with S100-immunopositive processes. We found that cells with processes located in pancreatic islets of human fetuses and children are similar to Schwann cells by their morphological and ultrastructural characteristics, immunopositive reaction for S100, and integration with nerve endings. In the pancreas of fetuses and children, Schwann cells are often seen in forming pancreatic islets and around the pancreatic ducts. The data suggests that Schwann cells can participate in the morphogenesis of human pancreatic islets.
Assuntos
Ilhotas Pancreáticas/ultraestrutura , Ductos Pancreáticos/ultraestrutura , Proteínas S100/genética , Células de Schwann/ultraestrutura , Autopsia , Pré-Escolar , Feto , Expressão Gênica , Idade Gestacional , Humanos , Imuno-Histoquímica , Lactente , Recém-Nascido , Ilhotas Pancreáticas/metabolismo , Microscopia Eletrônica , Ductos Pancreáticos/metabolismo , Células de Schwann/metabolismoRESUMO
Immunohistochemical study of distribution of chromogranin A (neuroendocrine cell marker) in the developing human pancreas was carried out. Immunopositive reaction to chromogranin A was detected in the primordial pancreas from the early period of development (8 weeks). The count of chromogranin A-positive cells in early fetuses significantly surpassed that of insulin- and glucagon-containing cells. Chromogranin A immunoreactive cells, but not cells reacting with antibodies to insulin and glucagon were detected in the pancreatic islets and pancreatic ducts during all periods of gestation. These results suggested that hormone synthesis by pancreatic endocrine cells was preceded by the expression of chromogranin A and hence, this marker could be used for studies of the mechanisms of development of the endocrine part of the pancreas.
Assuntos
Biomarcadores/metabolismo , Cromogranina A/metabolismo , Feto/embriologia , Pâncreas/metabolismo , Cadáver , Feto/metabolismo , Humanos , Imuno-HistoquímicaRESUMO
The role of neuron-specific enolase (glycolytic enzyme; marker of nerve fibers and Langerhans islet in human pancreas) in the development of type 1 diabetes mellitus was studied in autopsy specimens from 6 adult patients. Autopsied specimens of the pancreas from 7 subjects without carbohydrate metabolism disorders served as the control. Autopsied specimens of the pancreas from a child with the clinical diagnosis of type 1 diabetes mellitus, a child without carbohydrate metabolism disorders, and from 7 human fetuses of 15-40 weeks gestation were also studied. In control specimens, the neuron-specific enolase was detected in the pancreatic nerve fibers and Langerhans islets. Studies of pancreatic tissue specimens from adult patients with type 1 diabetes mellitus showed no immunopositive reaction to neuron-specific enolase in insulin-negative specimens. A possible mechanism of type 1 diabetes mellitus development is suggested.
Assuntos
Diabetes Mellitus Tipo 1/enzimologia , Ilhotas Pancreáticas/enzimologia , Fosfopiruvato Hidratase/metabolismo , Estudos de Casos e Controles , Humanos , Imuno-Histoquímica , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismoRESUMO
Immunohistochemical study revealed three types of neuroendocrine contacts in nutria pancreas. In most cases, the pancreatic islets and individual endocrine cells were associated with a diffuse neural network. Integration of neural ganglia with the islets and innervation of endocrine cells by projections of ganglionic cells were detected. It is hypothesized that the structure of neuroendocrine interactions plays different roles in the regulation of endocrine secretion.
