Further observations on the pharyngeal hypophysis and the postsphenoid in the mature male rat.

In an investigation into the pharyngeal hypophysis and the postsphenoid using seven hypophysectiomized mature male rats, a pharyngeal hypophysis and a craniopharyngeal canal was found in each of two rats. Cellular differentiation was noted in the pharyngeal hypophysis in both rats. In one rat the pharyngeal hypophysis was markedly larger than any seen to date. In both rats the pharyngeal hypophysis was continuous with tissue of similar histological appearance which extended the full length of the cranio-pharyngeal canal. The histological appearance of the pharyngeal hypophysis and of the specific intra-canal tissue was also similar to that of cystic areas in the sellar adenohypophysis in the normal rat. The data arising from the present investigation indicate that a well-defined cranio-pharyngeal canal can occur in the rat. The data also support the assumption that the sellar adenohypophysis may be continuous with specific tissue within a cranio-pharyngeal canal. The significance of the data in terms of reactive hypertrophy and cellular differentiation of the pharyngeal hypophysis and the specific intra-canal tissue following hypophysectomy must await further data on the volume and histology of such tissue in normal rats which possess a cranio-pharyngeal canal.