Morphology of the accessory (pharyngeal) adenohypophysis and its relationship with the pharyngeal tonsil in the human fetus

The pharyngeal pituitary was examined in human fetuses during weeks 16 to 32 of development by light microscopy with routine and histochemical treatment of slices. All the fetuses examined possessed a pharyngeal pituitary, which develops from the epithelium of the upper pharyngeal wall, just like the main pituitary. Rathke's pouch becomes transformed into a cord and grows towards the midbrain forming the hypophysis cerebri, while some cells at the base of the cord remain in the integumentary epithelium of the pharynx and give rise to the pharyngeal pituitary. This organ represents a group of long epithelial cords under the integumentary epithelium within the connective tissue of the pharyngeal mucosa. The cords contain light and dark cells with signs of a secretory cycle. The pituitary cords grow into the lymphoid tissue of the pharyngeal tonsil. The integumentary epithelium does not contain protective structures at the site of origin of the pharyngeal pituitary. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 8, pp. 211–214, August, 1995 Presented by N. K. Permyakov, Member of the Russian Academy of Medical Sciences