Immunocytochemical study of the diffuse neuroendocrine system cells in equine lungs.

This study was undertaken to investigate the presence of neuroendocrine cells (N.E.C.) by immunocytochemical means in equine lungs during three distinct evolutionary periods: fetal, neonatal and adult. The authors identified bombesin, somatostatin and calcitonin secretory cells. In the fetal lungs the N.E.C. were located in the interstitial tissue and exhibited greater immunoreactivity to bombesin than to the other two neuropeptides studied. A large number of calcitonin-producing cells and a smaller number of bombesin-positive cells were seen in the bronchial and bronchiolar epithelium of newborn Equidae. In the adult equine lungs far fewer N.E.C. were observed than in the earlier stages. Somatostatin-producing cells were not seen in neonatal or adult lung tissue.