The palatine tonsil
Last reviewed: 23.04.2024
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The palatine tonsilla palatum is located in the amygdala fossa tonsillaris, which is a depression between the divergent downward slanted tongue in the front and the hypogastric arch in the back. Above the amygdala, between the initial sections of these archs, there is a triangular-shaped supramaxial fossa (fossa supratonsillaris), which sometimes forms a rather deep bag-shaped pocket. The palatine tonsil has an irregular shape, close to the shape of the almond nut. The largest length (13-28 mm) of the palatine tonsil is noted in 8-30-year-olds, and the largest width (14-22 mm) is 8-16 years.
The medial free surface of the amygdala, covered with a multilayer flat (squamous) epithelium, faces the side of the pharynx. On this surface you can see up to 20 amygdala dimples (fossulae tonsillae), in which open almond crypts (cryptae tonsillares). The lateral side of the amygdala is attached to the connective tissue wall of the pharynx, which is called the capsule of the palatine tonsil. From this plate, in the medial direction, trabeculae (septa) leave the lymphoid tissue of the organ, which, if well expressed, separate the tonsil into lobules. In the thickness of the amygdala there are rounded dense accumulations of lymphoid tissue - lymphoid nodules of the amygdala. The greatest number of them is observed in childhood and adolescence (from 2 to 16 years). Nodules are localized near the epithelial cover of the amygdala and near the crypt. Lymphoid nodules of different sizes (from 0.2 to 1.2 mm). Most lymphoid nodules have breeding centers. Around the nodules is a diffuse interstitial lymphoid tissue, which between the nodules has the form of cellular strands up to 1.2 mm thick. The stroma of the amygdala is the reticular tissue. The fibers of this tissue form loops in which lymphoid cells are located.
Development and age specific features of the palatine tonsil
Palatine tonsils are laid in fruits 12-14 weeks in the form of thickening of the mesenchyme under the epithelium of the second pharyngeal pocket. In a 5-month-old fetus, the amygdala is represented by the accumulation of lymphoid tissue up to 2-3 mm in size. During this period epithelial cords begin to grow in the amygdala. Future crypts are formed. At the 30th week, crypts do not yet have a lumen, and around the epithelial cords there is a lymphoid tissue. By the time of birth, the amount of lymphoid tissue increases, individual lymphoid nodules appear, but without centers of reproduction (the latter are formed after birth). During the first year of the child's life, the tonsils are doubled (up to 15 mm in length and 12 mm in width), and by 8-13 years old tonsils are the largest and last about 30 years. After 25-30 years there is a pronounced age-related involution of the lymphoid tissue of the amygdala. Along with the decrease in the mass of lymphoid tissue in the body, a proliferation of connective tissue is observed, which is already noticeable already in 17-24 years.
[Vessels and nerves of the palatine tonsil
The branches of the ascending pharyngeal artery, the facial artery and the ascending branch, and the descending (from the maxillary artery) palatine and lingual arteries penetrate into the amygdala. Venous blood from 3-4 amygdala veins leaving the amygdala in the area of its external surface flows into the vein of the wing of the prominent plexus.
Innervation of the palatine tonsil is due to the fibers of the large palatine nerve (from the pterygoid node), the amygdala branch of the glossopharyngeal nerve and sympathetic fibers from the inner carotid plexus.