Neurotensin immunoreactive cells in the gastrointestinal epithelium of the chicken, pigeon and Japanese quail.

Distribution and frequency of neurotensin immunoreactive cells were investigated in the digestive tract of the chicken, pigeon and Japanese quail by an immunohistochemical technique. Immunoreactive cells were distributed in the epithelium of the pylorus, duodenum, jejunum, ileum, caecum and colon, but not in the epithelium of the tongue, crop and esophagus. The pylorus showed the highest frequency of the immunoreactive cells in the three species and the chicken revealed the highest frequency among them. In the chicken and Japanese quail, there were a few immunoreactive cells in the epithelium of the proventriculus and gizzard. In the caecum, the pigeon showed the highest frequency in the three species, although the size of the caecum is very small. These results indicate that neurotensin cells in the avian digestive tract show similar patterns of localization and suggest that the avian gastrointestinal tract acts as a wide source of neurotensin secretion.