Ultramicroscopic Examination of the Ovine Tonsillar Epithelia

As solid morphological knowledge of ovine tonsillar epithelia might contribute to a better understanding of the pathogenesis of several diseases including prion diseases, the epithelia of all tonsils of 7 one‐year‐old Texel sheep were examined using scanning and transmission electron microscopy. Major parts of the pharyngeal and tubal tonsils were covered by pseudostratified columnar ciliated epithelia that were interrupted by patches of epithelium containing cells with densely packed microfolds or microvilli, and cells with both microvilli and cilia. Smaller parts were covered by either flattened polygonal cells with densely packed microvilli or microfolds, squamous epithelial cells, or patches of reticular epithelium. The palatine and paraepiglottic tonsils were mainly lined by squamous epithelial cells with apical microplicae or short knobs. Additionally, regions of reticular epithelium containing epithelial cells with apical microvilli were seen. The lingual tonsil was uniformly covered by a keratinized squamous epithelium and devoid of microvillous cells and patches of reticular epithelium. The rostral half of the tonsil of the soft palate was lined by a pseudostratified columnar ciliated epithelium with characteristics of the pharyngeal and tubal tonsils. The epithelium of the caudal part resembled the epithelia of the palatine and paraepiglottic tonsils. Putative M cells, mainly characterized by apical microvilli or microfolds and a close association with lymphoid cells, seem manifestly present on the nasopharyngeal tonsils. The reticular epithelium of the palatine and paraepiglottic tonsils also harbor cells with small apical microvilli. The exact nature of these presumptive M cells should, however, be elucidated in functional studies. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

Histological and Ultrastructural Examinations of Porcine Tonsils

The histology and ultrastructure of porcine tonsils were studied. The porcine tonsils were lymphoepithelial organs situated at the opening of both the digestive and respiratory tracts. The tonsil of the soft palate in the oropharyngeal tract and the paraepiglottic tonsil in the laryngopharynx were mainly consisted of secondary lymphoid follicles encapsulated by connective tissue. The stratified squamous epithelia covering the tonsils and their crypts were frequently heavily infiltrated by lymphoid cells. The pharyngeal and tubal tonsils (TT) were situated in the nasopharyngeal tract. The cells of the pseudostratified columnar epithelia of the pharyngeal and TT were loosely connected, with large intercellular space. They consisted of scattered lymphoid follicles, aggregations of lymphoid cells and diffuse lymphoid tissues. Many high endothelial venules, specialized for the diapedesis of lymphoid cells into the tonsillar tissue, were detected in the four porcine tonsils. Therefore, the overall structures of the tonsils (the tonsil of the soft palate, the paraepiglottic tonsil, the pharyngeal and the TT) reflect their immune functionality in the oral and intranasal immunity. Anat Rec, 2012. © 2011 Wiley Periodicals, Inc.     

Fine structure of the anal tonsilliar epithelium in the laboratory shrew (Suncus murinus)

The epithelium of the anal tonsil of the laboratory shrew was studied by scanning and transmission electron microscopy, with particular attention focused on the structure of the epithelium lining the anal tonsillar crypt. The tonsillar crypt surface is lined by two kinds of epithelia: squamous epithelium, which is located mainly at the neck of the crypt and includes keratohyalin granules in the superficial layer, and reticular epithelium, which is invaded by many immigrating cells and has several micropores immigrating cells to pass through. In addition, basal granulated cells are present in the basal layer. These results suggest that the reticular epithelium of the anal tonsil belongs to the well-developed gut-associated lymphoid tissue (GALT) in the alimentary canal. It represents a specialized and important compartment in immunological function, similarly to the palatine tonsils of other mammals, and has as yet unknown roles in digestion.     

Immunoglobulin-containing cells in human tonsils as demonstrated by immunohistochemistry.

Intracellular immunoglobulin has been demonstrated in human palatine tonsils by the unlabelled antibody peroxidase-antiperoxidase complex (PAP) method in which rabbit antiserum to a range of human immunoglobulins (Igs) was linked to the PAP complex by an intermediate stage of swine antiserum to rabbit Ig. The effects of different methods of fixation and processing have been compared, formol-saline fixation giving the best results. The PAP technique proved greatly superior to the fluorescein isothiocyanate (FITC)-based technique, not only in sensitivity but in permitting study of the finer histological and cytological features. The lymphoid follicles are shown to have three distinct zones, two forming the follicle centre (zones (a) and (b)), and the third (zone (c)) the lymphocyte cap. Ig synthesis appeared to begin in the cells in zone (b). IgG, IgA, IgM, IgE and IgD were present in all tonsils, with IgG predominating, confirming that the tonsil resembles lymph nodes more closely than it does alimentary lymphoid tissue. Some follicles contained more than one type of Ig. The tonsil appears to have a well-developed T-dependent area, the lymphoid follicles forming a B-cell area. The structure of the tonsil would seem to facilitate contact between its lymphoid tissue and antigens in the crypts, and it is postulated that some T cells within the crypt epithelium, after contact with antigen, may leave the tonsil by the efferent lymphatics and enter the peripheral circulation by the thoracic duct, whilst other primed T cells interact with B cells in the follicle centres. Some B cells may then start to synthesize immunoglobulin, whilst others become memory cells in the lymphocyte 'cap' of the follicle.     

Morphology and immunology of the human palatine tonsil

At the surface of the respiratory and digestive organs the organism first comes into contact nasally and orally with various foreign agents and substances in the air and in food. The palatine tonsils are located at the centre of this strategic region. Immunological processes, both humoral and cellular, are initiated in the different specialised compartments of the palatine tonsils, such as the crypt epithelium, lymphoid follicles and extrafollicular region. Each compartment has a typical composition of lymphocytes and dendritic cell subsets. This review summarises current data on the anatomy, histology, and pathology of the human palatine tonsils, describes their fundamental immunological functions, and provides insight into the various interactions involved in the initiation of immune responses. The palatine tonsil is the only easily accessible human lymphoid organ and is often taken as an example for lymphoid organs. Although affections of the palatine tonsils constitutes an essential part in the clinical routine, it is still controversial whether tonsillectomy is of general benefit. This is of increasing importance since it has been discovered in the last few years that the palatine tonsils are reservoir and replication sites of HIV. Accepted: 24 July 2001     

腭扁桃体血管的应用解剖

在30例已固定的成人尸体头部标本上观察了腭扁桃体的动脉、静脉及其毗邻关系。腭降动脉及腭升动脉腭支主要分布于扁桃体的上极和上部;咽升动脉及腭升动脉主干分布于扁桃体的中部;面动脉主干及舌动脉则主要分布于扁桃体的下部和下极。以上各动脉分支均穿过咽上缩肌直接分带于扁桃体。腭扁桃体静脉先于其被膜下形成静脉网,再汇集成1～5支扁桃体静脉,后分别流入扁桃体旁静脉、咽静脉和舌静脉内。     

An electron and light microscope study of the caecal tonsil: The basic unit of the caecal tonsil

The caecal tonsil (CT) develops in the initial 4–18 mm of each of the chicken's caecal pouches. Utilizing scanning and transmission electron microscopy and light microscopy we identified the basic unit of the CT. The basic unit contains a central crypt with several primary branches, dense lymphoid tissue and germinal centers. The main structural design of the CT appears to correspond to the mammalian palatine and lingual tonsils.     

Study of human T and B lymphocytes with heterologous antisera. III. Immunofluorescence studies on tonsil sections.

Lymphoid cells from human palatine tonsils were identified on tissue sections by membrane or intracellular immunofluorescence (IF) staining. Used in an indirect technique, an anti-IgM and an anti-HTLA (human T lymphocyte antigen) antiserum gave complementary patterns of membrane IF, characteristic of the follicular organization. When serial sections were stained for each of the five classes, immunoglobulin-containing cells from all classes were found. Their relative frequencies were, in decreasing order: IgG: 61.6%; IgA: 17.3%; IgM: 12%; IgE: 7.5%; IgD: 1.6%. These differed from those of the gut-associated lymphoid tissue (IgA greater than IgG greater than IgM) and of the peripheral lymph nodes (IgG greater than IgM greater than IgA), but were close to those of mesenteric nodes. The absence of secretory component in tonsil was an additional difference from gut-associated lymphoid tissue and the relatively high proportion of IgE-containing cells, in the absence of recognized atopy, is another feature in common with mesenteric lymph nodes. Finally, slight differences between these results and those obtained on tonsil cell suspensions suggest that some degree of selection probably occurs during the isolation procedure.     

Oral tonsils: an immunoperoxidase study

Tissue morphometry and the distribution of cells containing immunoglobulin (Ig), J chain and secretory component (SC) were studied in eight oral tonsils. Quantitative immunohistochemistry revealed that IgG-containing cells predominated in all lymphoid compartments (follicles, extrafollicular areas and reticular epithelium) and that the IgG:IgA:IgM class ratios of the overall tonsillar immunocyte population were 13:8:2. Cells containing IgD and IgE were rare. IgG immunocytes showed no significant localisation within a given lymphoid compartment, whereas IgA cells were found predominantly in extrafollicular areas, especially adjacent to surface epithelium, and IgM cells were in follicles. J chain was present within IgM and some IgA cells. Tonsillar crypt and surface epithelium was negative for SC, suggesting that these structures are not directly involved in local mucosal immunity.     

Branchial cleft cysts. Histologic and immunohistochemical aspects

8 cases of branchial cleft cysts and 1 case of branchiogenic carcinoma were examined immunohistochemically for detectable keratin, immunoglobulins (IgG, IgA, IgM), carcinoembryonic antigen (CEA), factor VIII related antigen (Factor VIII RGA), and lysozyme. Lectin binding patterns were also determined. Histologically, cystic lining epithelia were classified into stratified squamous epithelium without keratinization, columnar epithelium with or without cilia, or a mixture of both. Almost all of the cases indicated accompanying lymphoid structures with germinal centers. Keratin expression in epithelial cells was slightly positive, and lectin binding affinities in them were similar to those of oral squamous epithelium. CEA was found on the surface border of columnar epithelial cells, but cystic epithelia in most of the cases were devoid of lysozyme. Endothelial cells of capillary vessels showed positive binding by UEA-1 lectin and the presence of factor VIII RAG. In the lymphoid structures, there were scattered strongly positive lysozyme-staining cells as well as a few lymphocytes bearing IgG, IgA, or IgM.     

Immunomorphological lymphocytic-tissue associations in the anterior gastrointestinal tract in human fetus

Prevalence of T-cell system of the immunity is found in the pharyngeal, lingual and palatine tonsils and lymph nodes. B-lymphocytes are much less numerous. Adenocytes consolidation in the structure of "pharyngeal hypophysis" is considered as additional part of the anterior hypophysis. The structure of the mucous membrane in the region of pharyngeal hypophysis is described. This membrane is deprived of protective epithelium and mucous glands.     

The enzyme histochemistry of lymphoid and non-lymphoid cells of the human palatine tonsil: a basis for the study of lymphomas

The distribution of various hydrolytic enzymes has been determined in 27 human palatine tonsils by means of conventional enzyme histochemical techniques, and lysozyme (muramidase) activity has been localised in eight tonsils by the unlabelled antibody peroxidase-antiperoxidase complex (PAP) method. The enzyme activities of various cell types are compared and the effect of various methods of fixation and processing discussed. The results suggest that arrangement of various histiocytic cells types within the tonsillar follicles and crypt epithelium is related to the processing of antigen. The PAP method for lysozyme demonstrates a smaller population of cells than is demonstrated by the alpha-naphthyl acetate esterase (ANAE) method. T-cells are demonstrated by the presence of dot-like ANAE activity in their cytoplasm. Large numbers of the lymphocytes of this type were located in the T-dependent areas of the tonsil, and are frequent beneath the crypt epithelium. The efferent lymphatic vessels appeared to contain an almost pure population of T-cells. The immunohistochemical method for lysozyme did not differentiate between T- and B-cell areas, dot-like activity being absent. As in other workers' studies on non-lymphoid cells of the murine spleen, several types of glass-adherent cells have been identified in short-term cell cultures from the human tonsil. True dendritic cells and branching macrophages differ in several ways (as in the mouse spleen). The tonsil is considered to be a useful control "reactive" lymphoid organ, to act as a baseline tissue in an extended study of morphology and enzyme histochemistry in the lymphomas.     

The Microanatomy of the Palatine Tonsils of the One‐Humped Camel (Camelus dromedarius)

Tonsils form a first line of defense against foreign antigens and are also a route of entry and a replication site for some pathogens. The palatine tonsils are the largest of all the tonsils. Despite their general importance, little is known about the microanatomy of the palatine tonsils of the one‐humped camel. Palatine tonsils of 10 clinically healthy male camels were obtained directly after slaughtering for human consumption. The tonsils were examined macroscopically and by light, scanning, and transmission electron microscopy. Palatine tonsils had the unique form of several spherical macroscopic nodules protruding into the pharyngeal lumen. These spherical masses were numerous and close together in the lateral oropharyngeal wall, with a few solitary nodules in the dorsal wall. Each nodule had one or two apical openings to crypts, and was enclosed by an incomplete connective tissue capsule and covered apically with stratified squamous keratinized epithelium. The tonsillar crypt was lined with stratified squamous non keratinized epithelium. Several lymphocytes infiltrated the epithelial layer, forming patches of reticular epithelium. Lymphoid follicles with obvious germinal centers extended under the epithelial surface. Diffusely localized lymphocytes were seen in the interfollicular region. High endothelial venules, dendritic cells, macrophages, and plasma cells were observed among these lymphocytes. The unique arrangement of palatine tonsils in separate units with individual crypts results in a very large surface exposed to antigen and indicates a significant immunological role of palatine tonsils in the camel. Anat Rec, 292:1192–1197, 2009. © 2009 Wiley‐Liss, Inc.     

Immunopathological and ultrastructural studies on the tonsil of gnotobiotic pigs infected with strain 67N of haemagglutinating encephalomyelitis virus

The 67N strain of haemagglutinating encephalomyelitis virus (HEV) was inoculated orally or nasally into ten 3-day-old gnotobiotic piglets. Tonsillar changes characterized by epithelial degeneration and lymphatic cell infiltration occurred in the crypt from post-inoculation days (PID) 5 to 7, and HEV was isolated from the tonsil on PID 3 and 5. Ultrastructurally, many HEV particles were found in the cisternae, cytoplasmic vesicules and extracellular spaces of crypt epithelium. Immunohistologically, many HEV particles were observed in the crypt epithelial cells in the early stage of infection. Thereafter, a large number of immunoglobulin (IgG, IgM and IgA)-containing cells were observed in the tonsil. The appearance of IgM-containing cells was coincident with the detection of neutralizing antibody in the serum. These findings suggest that HEV replication in the crypt epithelium stimulates the proliferative response of immunoglobulin (IgG, IgM and IgA)-producing cells.     

人胎儿腭扁桃体隐窝上皮超微结构研究

以电镜观察第４￣８月龄人胎儿腭扁桃体的超微结构。第４月龄扁桃体上皮开始形成上皮芽并长入其下的结缔组织形成隐窝；隐窝上皮内出现淋巴细胞、交错突细胞、巨噬细胞等浸润。随胎龄增长浸润细胞数量增多并渐扩展到上皮表层。第８月龄胎儿隐窝上皮表层有少数Ｍ细胞，具有较一般上皮细胞为多的微绒毛以胞质突起包绕和覆盖淋巴细胞。隐窝上皮下结缔组织中常见淋巴细胞、巨噬细胞等；毛细血管较丰富，有的血管紧贴上皮基膜分布。扁桃体     

An immunohistochemical study of branchial cysts.

Twenty five specimens of branchial cyst from the same number of patients have been examined. On staining with haematoxylin and eosin a consistent finding was that the mural lymphoid follicles were always aligned with their mantle zones towards the luminal epithelium. With conventional staining lymphatic sinuses were noted in 17 of the specimens, but with immunohistochemical staining these structures were apparent in 23 cysts. Their frequent occurrence in branchial cysts supports the theory that these lesions are derived from epithelial inclusions in lymph nodes. Immunohistochemical techniques for a range of other markers, using polyclonal and monoclonal antisera, showed a distribution of lymphoid and non-lymphoid tissue elements, as seen in lymph nodes and, for example, palatine tonsils. The lining luminal epithelium also shared many features in common with the crypt epithelium of tonsils.     

Terminally differentiated human intestinal B cells. J chain expression of IgA and IgG subclass-producing immunocytes in the distal ileum compared with mesenteric and peripheral lymph nodes

Two-colour immunofluorescence staining for intracellular J chain and IgA (or J chain and IgG) was performed on tissue sections of normal human ileal mucosa (eight adult kidney donors), mesenteric lymph nodes (MLN), peripheral lymph nodes, and palatine tonsils. The most prominent J chain positivity was seen for IgA (97.3%) and IgG (81.7%) immunocytes in the ileal lamina propria (LP). Moreover, the proportion of J chain-expressing extrafollicular immunocytes was significantly higher (P less than 0.05) in MLN than in peripheral lymph nodes for the IgA class (58.5% versus 25.6%); the same proportion for the IgG class was 45.9% versus 30.4%. In clinically normal palatine tonsils of adults, extrafollicular J chain expression was much lower than in peripheral lymph nodes; 14.2% for IgA cells and 5.5% for IgG cells. When related to subclass production, J chain expression was found to be higher for IgA2 than for IgA1 cells in all tissues examined (palatine tonsils excluded because of a small number of IgA2 cells), the difference being significant in MLN and ileal LP (P less than 0.05). The J chain positivity tended to be higher for all IgG subclasses in MLN than in peripheral lymph nodes; this difference was significant (P less than 0.05) for IgG2-producing immunocytes. Taking J chain expression as a marker of clonal immaturity, our results may reflect to some extent distribution of newly generated memory B cell clones from gut-associated lymphoid tissue to MLN, peripheral lymph nodes, and palatine tonsils in a strikingly decreasing order.     

Reticular crypt epithelium and intra-epithelial lymphoid cells in the hyperplastic human palatine tonsil: An immunohistochemical analysis

Extensive immunohistochemical analyses of the hyperplastic human palatine tonsil disclosed variegated B cell phenotypes on the lymphoid cells among the crypt epithelium. The reticular epithelial network was evident by cytokeratin immunostaining. The reticular epithelium near the crypt Iumen was positive for Iysozyme. Secretory component was negative, while HLA-DR was frequently expressed. Intramucosal small Iymphocytes, densely distributed in the Iuminal side, consisted mainly of B cells expressing CD19, CD20, CD21, CD22, CD45R, CD74, DBB42, HLA-DR, HLA-DQ, bcl-2 protein and surface lgM. Some B cells revealed mantle zone phenotypes (surface IgD+, CD5+, CD24+, DBA44+, CD10^--, DNA7^--). Cells of germinocyte phenotype (CD10+, DNA7+) were sparsely seen. A good number of intramucosal lymphoid cells were further labeled for CD11b, a phenotype of so-called B-1 cells. Plasma cells were clustered within the basal half. IgG was their major immunoglobulin class, followed by IgA, IgM and lgD classes. A smaller number of T cells (CD2+, CD3+, CD5+, CD45RO+, TCR αβ+) were identified among the epithelium. CD4+ cells predominated over CD8+ cells. TCR γΔ + cells were rare. Macrophages (CD68+), dendritic histio-cytes (S-100 protein+, CD1+), and natural killer cells (CD16+ or CD57+) were also dispersed. Another unique feature of this lymphoepithelial complex was the existence of HLA-DR intramucosal microvasculature, where lymphocyte recirculation was suggested. Proliferating cell nuclear antigen was detected commonly in the epithelial cells but rarely in the lymphoid cells. Possible lymphoepithelial interactions and morphologic similarities to the thymic medulla are discussed.     

Association between keratin staining patterns and the structural and functional aspects of palatine tonsil epithelium.

The keratin composition of stratified squamous epithelia has a complex pattern, which varies in different regions and as a result of pathological developments. The exact factors responsible for the characteristic keratin composition in a given epithelium are unknown. However, the environment, including factors from the connective tissue, is known to influence epithelial morphology and keratin composition. We here report that the reticulated squamous epithelium of the crypts of palatine tonsils shows an extensive staining for keratins 5 and 19 in basal as well as suprabasal cells, in contrast to neighbouring non-reticulated crypt epithelium and the epithelium at the tonsillar surface, in which staining is restricted to basal cells. The reticulation of the crypt epithelium is thought to be initiated by infiltration of immune-related cells in a preexistent non-reticulated epithelium. The extensive staining for keratins 5 and 19 in reticulated crypt epithelium correlates with the presence of numerous immune system-related cells and marked expression of intercellular adhesion molecule-1 (ICAM-1), thought to be involved in inflammatory and immunological responses. The results suggest that the massive lymphocytic traffic in the reticulated crypt epithelium and the overall distinct immune environment are responsible for the unique keratin staining pattern observed.