Developmental anatomy of the tonsil and its implications for intracapsular tonsillectomy.

OBJECTIVE: To describe the developmental anatomy of the human tonsil from the embryonic period through adulthood and to use this information to define the applicability of intracapsular tonsillectomy in the management of disease. DESIGN: Descriptive-anatomic. SUBJECTS: (1) Normal embryos and fetuses from two archival collections, (2) children with adenotonsillar hypertrophy and (3) adult autopsy material. RESULTS: The second branchial pouch is visible in the 4th post-conceptional week and demonstrates canalization and branching in the 8th week. Lymphoid infiltration of the lamina propria occurs in the seventh month of intrauterine life. Primary follicles form late in gestation, but germinal center stimulation does not occur until shortly after birth. During the first year of life, there is rapid proliferation of lymphoid elements and formation of active germinal centers. During the phase of maximum tonsillar hyperplasia, the lymphoid elements proliferate rapidly, increasing tonsillar bulk. In senescence, there is involution of the lymphoid elements and proliferation of fibrous tissue in the capsule and trabeculae. The overall bulk of the tonsil is much decreased. CONCLUSIONS: There is an intimate relationship between the epithelial and lymphoid components of the tonsil which continues through life. To adequately control upper airway obstruction of tonsillar origin and recurrent tonsillar infection in childhood, total or near total intracapsular tonsillectomy likely will prove the minimum acceptable surgical intervention. Changes in tonsillar anatomy after the first decade may alter operative choice in older patients.

Histological studies on the ontogeny of bovine palatine and pharyngeal tonsil: germinal center formation, IgG, and IgA mRNA expression.

The development and distribution of lymphocyte subsets in calf palatine and pharyngeal tonsil were examined. During prenatal development, B cells were distributed in the subepithelial area, and T cells and MHC class II(+) cells were found in the deep layer of B-cell area, respectively, in both tonsils. At neonatal stage, lymphoid follicle containing a few CD4(+) cells have been formed in both tonsils. IgG(+) and IgA(+) cells were found in the parafollicular and epithelial area. At 3 months old, many germinal centers were recognized in both tonsils. CD4(+) cells and IgG mRNA expression were detected in light zone of germinal centers. Many IgG, and IgA mRNA expressions also could be detected in the parafollicular and subepithelial area of both tonsils. The data suggest that both tonsils have an important role of local immune defense against invading antigen after birth. The comparison of the histological characteristics of tonsil and Peyer's patch during ontogeny is also discussed.

Morphological study of development and functional activity of palatine tonsils in embryonic age.

Palatine tonsils play an important role in the development of the immune system, being the first organ in the lymph system which analyses and reacts to antigenic stimulation. In this study, the peritonsillar area of Waldeyer's ring was investigated in 88 normal human embryos which were examined histologically and immunohistochemically. The progressive development of palatine tonsils during embryonic life is discussed. The first appearance of tonsils is in about the 14th-15th week followed by a parallel development of B- and T-cell regions which accounts for the high incidence of non mucosa-associated lymphoid tissue lymphomas among all tonsillar lymphomas and the higher incidence of T-cell-lymphomas, in comparison to the mucosa-associated lymphoid tissue of the digestive system. The way in which the human body develops the palatine tonsils quickly and prepares them to react to the first antigenic stimulation, are discussed.

Langerhans cells in the epithelium of the human palatine tonsil during the prenatal development.

In the 18th week of the prenatal life large light cells of mesenchymal origin enter the crypt epithelium of the palatine tonsil to start its reticularisation. They are considered precursors of Langerhans cells.

Development and immunophenotyping of the pharyngeal tonsil (adenoid) in cattle.

Immunoperoxidase staining and electron and light microscopy were used to characterize the development of the pharyngeal tonsil in 98 cattle aged between 30 days of gestation and 12 years. The rugae of the pharyngeal tonsil were poorly formed before 95 days of gestation. Microvillous (M) cells associated with intra-epithelial leucocytes (lympho-epithelium) were scattered among ciliated and goblet cells covering most of the surface in post-natal animals. Intra-epithelial leucocytes were rare in fetuses, but ciliated and M cells could be distinguished. Leucocytes of the lamina propria started to accumulate at approximately 120 days of gestation. A loose accumulation of mononuclear cells progressed into a B-cell rich upper and T-cell rich lower layer, with typical lymphoid tissue organization in post-natal animals and lymphoid involution in aged cattle. Primary lymphoid follicles formed at 5 months of gestation, but germinal centres did not form until 2 to 4 weeks after birth. Except for null cells, the relative number of cells staining for each leucocyte phenotype or MHC class II antigen increased with age, especially during the neonatal period. The early development, strategic location and specialized structure of the pharyngeal tonsil suggest an important role in modulating inhaled antigens in cattle. Fetal and neonatal calves had minimal lymphoid tissue priming, as indicated by lack of secondary follicles, low MHC class II expression and few intra-epithelial leucocytes. The phenotypic differences may be relevant to the increased susceptibility of calves to infectious diseases shortly after birth.

The ontogeny of human lymphocyte recirculation: high endothelial cell antigen (HECA-452) and CD44 homing receptor expression in the development of the immune system.

In the present report we have studied the expression of a lymphocyte homing receptor, the CD44 antigen, and of HECA-452, a high endothelial-specific antigen, during the development of the human immune system. We found that prothymocyte immigrants of the thymus already expressed the CD44 antigen. Similarly, the first peripheral T lymphocytes in fetal lymph nodes, tonsils and gut-associated lymphoid tissue were also CD44+. Cortical thymocytes and germinal center cells were CD44-. CD44 antigen expression was, thus, not limited to mature recirculating lymphocytes. This suggests that CD44 may not only be involved in recirculation of mature lymphocytes but also in the migration of prothymocytes to their site of maturation, i.e. the thymus. High endothelial venules (HEV) were not demonstrable at the early onset of lymphocyte immigration into the developing lymphoid organs. However, when large-scale influx of lymphocytes occurred, it paralleled HEV development. HECA-452 antigen expression preceded the morphological transformation of endothelium into a HEV phenotype. Expression of this antigen therefore, independently reflected the specialized nature of high endothelium. In a patient with complete DiGeorge's syndrome normal HEV developed, indicating that the presence of T lymphocytes is not a requirement for HEV development. Interestingly, a subpopulation of venules located in the thymic medulla near the cortico-medullary junction expressed the HECA-452 antigen. These vessels, which had flat or intermediately high endothelium, are probably involved in lymphocyte migration to the thymus.

Development and functional anatomy of the human tonsilla palatina.

The tonsilla palatina, belonging to the gut-associated lymphoepithelial organs (GALT), shows close morphological and functional correlation between the lymphatic tissue of mesenchymal origin and the endodermal epithelium of the second pharyngeal pouch. During the 4th fetal month epithelial crypts grow down into the connective tissue and are infiltrated by non-epithelial cells. In the underlying lymphoid tissue the first primary follicles with precursors of follicular dendritic reticulum cells can be localized already in the 14th fetal week post conceptionem (p.c.). The parafollicular areas develop into T-cell regions. Interdigitating cells in these regions as well as within the crypt epithelium express the HLA-DR antigen. They were frequently found in close contact with T-helper cells. This fact is discussed as an indication of the tonsillar crypt epithelium partly serving as T-cell region. But also B-cells and macrophages invade the crypt epithelium in great numbers with a distinctly different distribution. Natural killer (NK) cells (Leu-7-positive) are localized within the crypt epithelium. Small Leu-7-positive lymphocytes (probably precursors) have been found to be numerous in the germinal centers. The interaction of specific stationary cells in the T-cell and B-cell regions is obviously an important factor for the maturation of different subpopulations of immunocompetent lymphoid cells.

The embryogenesis and anatomy of Waldeyer's ring.

The developmental history of the embryonic germ disk is briefly traced through the bilaminar, trilaminar, and bodyfold stages with emphasis on the pharyngeal arches, pouches, and clefts. This is followed by a discussion of the genesis and adult anatomy of the tonsillar tissues.

[Development and structure of the lymphoepithelial pharyngeal ring in the Macacus rhesus]. / Razvitie i stroenie limfoépitelial'nogo glotochnogo kol'tsa Macacus rhesus.

The lymphoepithelial pharyngeal ring has been studied in fetuses and 6-8-month-old monkeys (Macacus rhesus) by means of macro- and microscopical methods. The pharyngeal, palatile and lingual tonsils and a poorly manifested laryngeal tonsil have been revealed. The anlage of the lingual tonsil occurs later than that of the other ones (in fetuses of 60-73 mm of the parietal-coccygeal length), when the palatile and pharyngeal tonsils are already inhabited with lymphocytes. By the end of the embryonal period, the main structural components are already formed in all the tonsils, but their functional activity is not yet manifested. During the postembryonic period certain differences are revealed in the tonsil structure, they are presented as the germinative centers formation, appearance of active macrophages and plasma cells. A close connection between the lingual, pharyngeal and laryngeal tonsils with the glandular tissue is noted.

[Morphological characteristics of the function of the tonsil as an organ of immunogenesis]. / Morfologicheskaia kharakteristika funktsional'nogo sostoianiia nebnykh mindalin kak organa immunogeneza.

The review deals with the problem of the necessity to evaluate the immunological state of palatine tonsils in various pathologic conditions on the basis of morphological studies. The methods of investigation allowing the intensity of cellular and humoral immunity to be assessed are described. It is emphasized that a combined approach including morphological examinations of the palatine tonsils together with immunological methods used clinically is optimal for the evaluation of the immunological state of palatine tonsils. Investigation of the immunomorphological condition of palatine tonsils is important both for the evaluation of changes in the tonsils themselves and for characterization of the entire system of immunogenesis organs.

The development of the human tonsilla palatina.

Tonsils of human fetuses at the 8th to the 28th gestational week (g.w.) were investigated by electron microscopy, enzyme histochemistry, and immunohistochemistry on cryostat sections. The development of the tonsilla palatina starts during the 14th g.w. when the mesenchyme underlying the mucous membrane of the tonsillar cavity becomes invaded by mononuclear wandering cells. In fetuses of about the 16th g.w. epithelial crypts grow down into the connective tissue and are infiltrated by T-lymphocytes. At the same time, precursors of interdigitating cells (IDC) can be identified among the epithelial cells. Frequently, lymphocytes and IDC-like cells are in close contact. From these findings it is concluded that the infiltrated crypt epithelium in the human tonsilla palatina represents a T-cell region. Primary follicles develop in earlier fetal stages than in all other secondary lymphoid organs. They contain precursors of dendritic reticulum cells and lymphoid cells that belong to the B-cell line. These primary follicles may be considered as the first assemblage of B-cell regions in human fetal lymphoid tissue. The present findings indicate that the formation of different stationary elements during the development of B-cell regions and T-cell regions is an important factor for the homing and antigen-dependent maturation of different subpopulations of immunocompetent lymphoid cells.

Muscular anatomy of the tonsil and tonsillar bed: a reexamination.

A study was designed to investigate the muscular relations to the tonsil and tonsillar bed in man. Twenty-one histologically prepared human fetal specimens were examined. Muscle bundles from the palatopharyngeus and stylopharyngeus muscles and the amygdaloglossus muscle were found to relate to the tonsillar capsule in such a way as to suggest that during swallow, the tonsils may be moved laterally to permit a wide and unobstructed pharyngeal port.

Plaque assay and improved yield of human coronaviruses in a human rhabdomyosarcoma cell line.

Propagation and plaque assay of human coronavirus prototypes were studied in two human cell lines: a diploid fetal tonsil (FT) and a heteroploid rhabdomyosarcoma (RD) cell lines. Plaques, observed within 2 to 3 days on FT cell monolayers with both 229E and OC43 viruses, appeared as colorless areas after staining with neutral red or crystal violet, whereas neutral red staining was required for visualization of plaques on RD cells. The plating efficiencies were approximately equal between the two cell lines, but virus assay by plaque formation was 15- to 30-fold more efficient than tube dilution assay with 50% endpoints. The discrepancy between 50% endpoint and plaque-forming unit values was striking and appeared to result from the fact that killing of cells (particularly RD cells) by coronaviruses was not accompanied by visible changes in the cells but killing was detected by the failure of infected cells to stain with a vital dye. The latent phase in one-step growth curves was 5 to 6 h for both viruses in either cell line, but the maximum yield of intracellular virus was reached in 18 to 20 h for FT cells and 24 to 28 h for RD cells. Virus release also differed between the two cell lines: in FT cells, the maximum yield of extracellular virus was reached 2 to 3 h later than that of intracellular virus, whereas in RD cells, the difference was 5 h for 229E virus and 10 h for OC43 virus. Although both cell lines appear equally useful for plaque assay, RD cells would be preferred for mass virus propagation because yields (5 X 10(8) plaque-forming units per ml) were 10-fold higher than in FT cells, a finding true for both virus prototypes.

Alkaline phosphatase activity in the human tonsils and its relation to tonsillar diseases.

Alkaline phosphatase activity was examined in the human tonsils in fetal life and after repeated attacks of acute tonsillitis and in quinsy. Gomori's metal precipitate technique was used to demonstrate the phosphatase activity using four different substrates: sodium beta-glycerophosphate and adenosine triphosphate at pH 9, riboflavin 5-phosphate at pH 9.2 and 5-monophosphoric acid at pH 8.3. (2) The phosphatase activity differs somewhat according to the phosphate ester used as a substrate illustrating an example of 'substrate specificity'. (3) Alkaline phosphatase activity was increased in the case of both acute and chronic inflammation. This increase has been discussed in relation to such phenomena as transformation of lymphocytes into macrophages and antibody formation.