[Oropharyngeal lymphoid tissue as a bursa-equivalent structure: embryological and clinical considerations].

If we examine with an ontogenetic viewpoint the tissues giving origin to both thymus and avian bursa of Fabricius, we can't ignore that they are primary lymphoid organs connected to areas of ecto-entodermic junctions. They have a strong development in the embryonic life while tending to regress in the adult. The analysis of the organogenesis clarifies this affirmation. In the human cephalic district we know of various ectoentodermic stratification areas: the branchial pockets and the Remake pharyngeal membrane. The oral-pharyngeal lymphoid tissue is histogenetically linked to the stem-cells of the marrow which migrate to occupy an initially ecto-entodermic milieu. Structural and ontogenetic analogies of embryological nature lead to an identification of the oral-pharyngeal lymphoid tissue in man with the avian bursa of Fabricius. Therefore we deem it very indicative that a humoral immunological deficiency syndrome appears in subjects with the atrophy of the Waldeyer ring; above all considering that an experimental model of the humoral immunological deficit has been reproduced in chicken surgically or hormonally bursectomized.