This communication summarizes the observations of a research on the embryology, bacteriology and pathology of the pharyngeal tonsil.
Behind the oral plate in the middle line of the roof of the pharynx, anterior to the basioccipital, there is a depression called Sessel's pocket. Its embryologic significance is not understood, but it may be the remains of the pharyngeal opening of the notochord. In and around this recess, the pharyngeal or Luschka's tonsil develops.About the fourth month of fetal life, faint striae appear on this part of the posterior pharyngeal wall, and microscopic examination shows the tissue to consist of reticular tissue enclosing in its meshwork a few scattered lymphocytes. Development of this diffuse lymphoid tissue continues in the superficial fibers of the tunica propria of the pharyngeal mucosa until at 5½ months the pharyngeal tonsil appears as a definite organ. Mucous glands are developed at the base and