Diffuse neuroendocrine system

The diffuse neuroendocrine system (DNES) summarizes hormone-producing cells that share certain characteristics with nerve cells ( neurons ) and are found individually or in small groups in the surface epithelium of various organs . Particularly common in the gastrointestinal tract , but also in the epithelium of the respiratory tract and in the urinary and sexual apparatus . They secrete i. d. R. Monoamines and various peptides and express proteins ( Chromogranin A , Synaptophysin ) that are typical of neurons . In the past, the term APUD (Amine Precursor Uptake and Decarboxylation) was also used for some of these cells .

The functions of these cells are only partially understood. In the gastrointestinal system, the neuroendocrine cells are involved in coordinating gastric acid production, insulin release and intestinal motility. The physiological tasks of neuroendocrine cells in the bronchial tree and urogenital tract are still unclear.

The DNES includes:

• APUD cell system: family of APUD cells.
  • APUD-I cells (direct descent from the neural crest ):
    • C cells of the thyroid gland
    • Carotid body type 1 cells,
    • Cells of the sympathetic trunk ,
    • Adrenal medulla cells , melanoblasts
    • endocrine cells of the urinary and reproductive system
  • APUD-II cells (descent from placode or specialized ectoderm ):
    • Hypothalamus cells containing oxytocin , vasopressin , TRF, LHRH , SRH , CRF and the like SRIF
    • LHRH-containing Zirbeldrüsenzellen
    • Parathyroid cells
    • Cells of the adenohypophysis with STH , prolactin , FSH , LH , corticotropin , MSH and the like TSH
    • Placenta cells with gonadotropin u. Somatomammotropin
• APUD-III cells (descent from neuroendocrine-programmed ectoblasts; see also intestinal hormones):
  • Pancreas (B, A, D, D1, PP),
  • Stomach (G, ECL, A, D, EC1),
  • Small intestine (S, I, D, D1, EC, EC1, EC2, K, N)

• Merkel cells of the skin

Diseases

Cells of the DNES can be the cause of mostly rare tumors, some of which then produce hormones and are often particularly malignant. Examples:

• Small cell lung cancer
• Medullary thyroid cancer
• Malignant melanoma
• Merkel cell carcinoma
• Insulinoma
• VIPom
• Carcinoid

Individual evidence

1. ↑ Lüllmann-Rauch, Renate: Pocket textbook histology: 10 tables . 4th, completely revised Ed. Thieme, Stuttgart 2012, ISBN 978-3-13-129244-5 .