Palatine tonsil

The palatine tonsil (tonsilla palatum) is paired and located in the tonsillar fossa (fossa tonsillaris), which is a depression between the palatoglossal arch in front and the palatopharyngeal arch behind, which diverge downwards. Above the tonsil, between the initial sections of these arches, is the triangular supratonsillar fossa (fossa supratonsillaris), which sometimes forms a fairly deep saccular pocket. The palatine tonsil has an irregular shape, close to the shape of an almond. The greatest length (13-28 mm) of the palatine tonsil is observed in 8-30-year-olds, and the greatest width (14-22 mm) is observed at 8-16 years of age.

The medial free surface of the tonsil, covered with stratified flat (squamous) epithelium, faces the pharynx. On this surface, up to 20 tonsillar pits (fossulae tonsillae) are visible, into which the tonsillar crypts (cryptae tonsillares) open. The lateral side of the tonsil is adjacent to the connective tissue membrane of the pharyngeal wall, which is called the capsule of the palatine tonsil. From this plate, trabeculae (partitions) extend medially into the lymphoid tissue of the organ, which, if they are well expressed, divide the tonsil into lobules. In the thickness of the tonsil, there are rounded dense accumulations of lymphoid tissue - lymphoid nodules of the tonsil. The greatest number of them is noted in childhood and adolescence (from 2 to 16 years). The nodules are localized near the epithelial cover of the tonsil and near the crypts. Lymphoid nodules of different sizes (from 0.2 to 1.2 mm). Most lymphoid nodules have centers of reproduction. Around the nodules there is diffuse internodal lymphoid tissue, which between the nodules looks like cellular cords up to 1.2 mm thick. The stroma of the tonsil is reticular tissue. The fibers of this tissue form loops in which the cells of the lymphoid series are located.

Development and age-related features of the palatine tonsil

The palatine tonsils are laid in fetuses of 12-14 weeks in the form of a thickening of the mesenchyme under the epithelium of the second pharyngeal pocket. In a 5-month fetus, the tonsil is represented by an accumulation of lymphoid tissue up to 2-3 mm in size. During this period, epithelial strands begin to grow into the forming tonsil. Future crypts are formed. At the 30th week, the crypts do not yet have a lumen, and lymphoid tissue is located around the epithelial strands. By the time of birth, the amount of lymphoid tissue increases, individual lymphoid nodules appear, but without reproduction centers (the latter are formed after birth). During the first year of a child's life, the size of the tonsil doubles (up to 15 mm in length and 12 mm in width), and by the age of 8-13, the tonsils have their largest dimensions and remain so until about 30 years. After 25-30 years, there is a pronounced age-related involution of the lymphoid tissue of the tonsil. Along with a decrease in the mass of lymphoid tissue in the organ, there is an proliferation of connective tissue, which is already clearly visible at 17-24 years.

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Vessels and nerves of the palatine tonsil

The branches of the ascending pharyngeal artery, the facial artery, and the branches of the ascending and descending (from the maxillary artery) palatine and lingual arteries penetrate the tonsil. Venous blood flows through 3-4 tonsillar veins, leaving the tonsil in the area of its outer surface, into the veins of the wing of the prominent plexus.

The innervation of the palatine tonsil is carried out by the fibers of the greater palatine nerve (from the pterygopalatine ganglion), the tonsillar branch of the glossopharyngeal nerve and sympathetic fibers from the internal carotid plexus.