Abstract
Prothymosin alpha is a polypeptide whose function is still a matter of debate. The present paper represents the first morphological description of the prothymosin alpha distribution in the human and rat digestive tract tissues using immunohistochemical techniques. In these epithelia prothymosin alpha immunostaining was localized in the nuclei of the proliferating cells, e.g. in the basal layer cells of the oesophagus, cells of the isthmus and the neck of the gastric glands, and crypt cells in the small and large intestines. At the ultrastructural level, prothymosin alpha immunolabelling was evident in the nucleus, being confined to euchromatin. The present data indicates that prothymosin alpha expression in the digestive tract epithelia is associated with proliferating cell populations. In agreement with this hypothesis, we found that the patterns of distribution of prothymosin alpha and proliferating cell nuclear antigen were similar. The distribution of prothymosin immunoreactivity was also similar to that obtained for bromodeoxyuridine when the animal was sacrificed 12hr after injection. The finding that intracellular distribution of the prothymosin alpha in the digestive tract epithelia is identical to that found in other tissues supports the idea that prothymosin alpha must play a universal role in proliferating cells.
