Shortening of the Bovine Tongue According to Regulation (EC) 999/2001 is not Complying with the Current Legal Definition of Specified Risk Material – a Macroscopical and Histological Preliminary Study

The full elimination of all specified risk material (SRM) in food of animal origin is crucial for consumer protection and is of high priority in inner EU trade. Among other tissues, the tonsils of cattle are considered as SRM. The aim of this study was to evaluate whether the ‘cut at the back of the tongue just before the tongue bones’ required by EC regulation is sufficient to remove tonsils and lymphatic tissue completely. Eight skulls from cattle were collected for the simulation of a vertical cut according to the EC regulation and the detection of the target at the back of the tongue. Further, specimens of the lingual mucosa were cut out from two tongues and examined microscopically. The most caudal of these specimens was from the macroscopically visible part of the lingual tonsil. The most rostral specimen contained the most caudal Papilla vallata. Simulation of the obligatory ventro‐dorsal cut yielded hits at varying locations on the dorsal surface of the tongue, sometimes including tissue of the lingual tonsil. Histological examination of the lingual mucosa gave clear evidence that lymphatic tissue resembling the tissue of a tonsil in terms of its histological organization and infiltration of the mucosal epithelium could even be found in areas with no macroscopically visible lingual tonsils.     

Bovine lingual tonsil: histomorphological characteristics with special reference to the follicular dendritic cells

In the bovine, the lingual tonsil is localized at the lingual radix. However, as the expansion of the tonsillar tissue was presumed to be much larger than the macroscopically visible part, selected specimens from the bovine tongue were examined to clarify if lymphatic tissue of the lingual tonsil was present rostral of a defined macroscopical landmark, i.e. rostral of the most caudal of the papillae vallatae. The identification of the lymphoreticular system was validated by means of the detection of reticulum cells, especially follicular dendritic cells (FDC). They characterize the tonsillar lymph nodules and distinguish them structurally from unspecific accumulations of lymphocytes. In our study, two monoclonal antibodies, i.e. CNA.42 and D46, detected bovine FDC cells in situ. 'Organized' lymphoid tissue--i.e. solitary lymph nodules and aggregations of lymph nodules, both either with or without surrounding connective tissue, and with or without crypts, but with immunopositive reactions for FDC--could be observed up to 30 mm rostral of the most caudal of the papillae vallatae. As these formations were not identified macroscopically, they shall be referred to as the disseminate part of the lingual tonsil.     

Pathogenesis of experimental bovine spongiform encephalopathy: preclinical infectivity in tonsil and observations on the distribution of lingual tonsil in slaughtered cattle

The infectivity in tissues from cattle exposed orally to the agent of BSE was assayed by the intracerebral inoculation of cattle. In addition to the infectivity in the central nervous system and distal ileum at stages of pathogenesis previously indicated by mouse bioassay, traces of infectivity were found in the palatine tonsil of cattle killed 10 months after exposure. Because the infectivity may therefore be present throughout the tonsils in cattle infected with BSE, observations were made of the anatomical and histological distribution of lingual tonsil in the root of the tongue of cattle. Examinations of tongues derived from abattoirs in Britain and intended for human consumption showed that macroscopically identifiable tonsillar tissue was present in more than 75 per cent of them, and even in the tongues in which no visible tonsillar tissue remained, histological examination revealed lymphoid tissue in more than 90 per cent. Variations in the distribution of the lingual tonsil suggested that even after the most rigorous trimming of the root of the tongue, traces of tonsillar tissue may remain.     

Distribution of the lingual tonsils of cattle designated as specified risk materials

The tonsils of cattle, including palatine tonsils, pharyngeal tonsils, tubal tonsils and lingual tonsils, are designated as specified risk materials (SRM). However, the detailed distribution of lingual tonsils in cattle is unknown. We therefore histologically examined their distribution in 198 tongue specimens from cattle. The examinations confirmed that the presence of lingual tonsils was limited to the tissue of the lamina propria on the dorsal and lateral aspects of the tongue, not reaching the muscular layer below. More than 90% of the lingual tonsils were located between the distribution center of the vallate papillae and the radix linguae (root of the tongue). However, they were also found in the area extending from the lingual torus to the rostral-most vallate papilla in an individual, suggesting that the complete removal of the lingual tonsils requires elimination of the lamina propria extending from the lingual torus to the radix linguae.     

Anatomical and histological aspects of the bovine lingual tonsil

The localization of the bovine lingual tonsil is described as a prerequisite for the removal of specified risk material from the tongue meat in order to restrict the risk arising from bovine spongiform encephalopathy (BSE) to public health. The major part of this tonsil can be located macroscopically by the openings of its follicular crypts at the root of tongue. This part consists of organized aggregations of lymph nodules. Additional solitary primary lymph nodules and diffuse accumulations of lymphocytes are macroscopically invisible but are bilaterally present in the area extending 2 cm caudal to 3 cm rostral to the last vallate papillae. By sectioning the tongue 3 cm rostral to the last vallate papillae, undermining the lingual mucosa to the level of these papillae and making a transverse cut towards the lingual process of the basihyoid bone, the greater part of the lingual tonsil can efficiently be removed. Finally, immunohistochemical staining demonstrated the presence of T and B lymphocytes, suggesting that the bovine lingual tonsil can be considered as a site where an immune response can be induced.     

Anatomical localisation and histology of the ovine tonsils

The topography and histologic structure of the various tonsils were studied anatomically and microscopically in 15 sheep aged between 9 and 15 months. The palatine, pharyngeal and paraepiglottic tonsils were readily visible macroscopically. They consisted mainly of secondary lymph nodules and were encapsulated in dense connective tissues. The epithelium covering the tonsils and their crypts was frequently infiltrated heavily by lymphocytes. The tubal tonsil and the tonsil of the soft palate were macroscopically visible after fixation in 2% acetic acid. These tonsils consisted of scattered lymph nodules, aggregations of lymphocytes and diffuse lymphoid tissue. They were not encapsulated, and therefore the borders of these tonsils could not be clearly delineated. The lingual tonsil was not macroscopically visible in sheep and consisted of scattered small aggregations of lymphocytes.     

Histological characteristics and stereological volume assessment of the ovine tonsils

Tonsils form a first line of defence against foreign antigens and therefore play a key role in immunity. Since documented information about ovine tonsils is limited, a study was performed in which the morphological characteristics and the volume of lymphoid tissue present in each ovine tonsil were determined. The tonsils of five adult healthy sheep were examined histologically and the volumes were estimated using the Cavalieri method. The pharyngeal tonsil had a mean volume of 1296.1 ± 205.9 mm³ and was by far the largest ovine tonsil, followed by the paired palatine tonsil with a mean volume of 715.0 ± 110.5 mm³. The tonsil of the soft palate, the paired tubal and paraepiglottic tonsils and the lingual tonsil were much smaller with a mean volume of, respectively, 90.3 ± 24.9 mm³, 80.1 ± 24.3 mm³, 29.7 ± 11.8 mm³ and 10.1 ± 2.8 mm³. The folds and crypts of the pharyngeal and palatine tonsils were covered by a reticular and a non-reticular epithelium. Both tonsils were mainly composed of primary and secondary lymph follicles. The palatine tonsils contained 1–3 crypts with a few secondary infoldings. Lymphoid tissue in the tonsil of the soft palate was located at the nasopharyngeal (dorsal) side of the soft palate. The tubal tonsil was lined with a pseudostratified columnar ciliated epithelium and consisted of scattered lymphoid cells and lymph follicles. The paraepiglottic tonsil consisted of lymph follicles and aggregated lymphoid cells. Its overlying keratinized stratified squamous epithelium was folded and often heavily infiltrated by lymphocytes. The ovine lingual tonsil was not macroscopically visible and did not contain clearly distinguishable lymph follicles. It consisted of aggregations of lymphoid cells that were mainly located within the vallate lingual papillae.     

Differences between the ovine tonsils based on an immunohistochemical quantification of the lymphocyte subpopulations

In sheep, the pharyngeal first defence line against oral and inhaled antigens is organized in six tonsils. Since tonsils are regarded as secondary lymphoid tissue and part of the acquired immune system which is subjected to induction through contact with antigens, an evaluation of the different lymphocyte populations in tonsils is useful to determine a tendency of the specific tonsils to more inductive or more effective immunity. By means of immunohistochemistry, different lymphocyte populations were quantified and localized using a panel of eight antibodies, i.e. anti-CD45, anti-CD21, anti-CD2, anti-CD3, anti-CD4, anti-CD8, anti-WC1 and anti-Ki67. The CD21+ B lymphocytes were localized within the tonsillar lymphoid follicles. The CD2+/CD3+ T lymphocytes were numerous in the interfollicular regions and were aligned underneath and within the epithelium but were also observed at the CD21+ pole of the lymphoid follicles. Near the lingual and tubal tonsils, and the tonsil of the soft palate, the CD45+ cells around the seromucous glands and in the lamina propria were mainly CD3+ T cells. In all tonsils, the WC1+ gamma delta T cells formed a small lymphocyte population which harboured the lamina propria and the interfollicular region. The relative percentages of the different lymphocyte populations of the large palatine and pharyngeal tonsils, which are macroscopically the most developed, were comparable. In contrast, the lingual tonsil was significantly different from the other tonsils not only by its small size and lack of lymphoid follicles, but also by the lymphocyte populations. Based on the lymphocyte populations, the ovine tonsils can be divided in three groups with the tonsil of the soft palate, the tubal and paraepiglottic tonsil forming an intermediate between the palatine and pharyngeal tonsils as true tonsils on the one side, and the lingual tonsil as a scattered lymphocyte aggregation on the other side.     

Histology, immunohistochemistry and ultrastructure of the equine palatine tonsil

The palatine tonsils of five young horses formed 10-12 cm elongated follicular structures extending from the root of the tongue on either side to the base of the epiglottis and lateral to the glossoepiglottic fold. The stratified squamous non-keratinized epithelium of the outer surface was modified into crypts as reticular epithelium by heavy infiltration of lymphoid cells from underlying lymphoid follicles. In places, lymphoid tissue reaching almost to the surface and with only one to two cell layers intact was identified as the lymphoepithelium. Langerhans cells with Birbeck granules were interspersed between epithelial cells. Lymphoid tissue organized in lymphoid follicles constituted the parenchyma of the palatine tonsil. CD4-positive cells were more numerous and CD8-positive lymphocytes less numerous compared with their distribution in the lingual tonsil. B cells and macrophages were also more numerous than in the lingual tonsil and lectins showed a different pattern of attachment. M cells were not observed. High endothelial venules with well-developed vesiculo-vacuolar organelle had structural evidence of transendothelial and interendothelial migration of lymphocytes. Striated muscles as seen in the deeper lamina propria mucosae of the lingual tonsil were absent. The immunohistological and ultrastructural characteristics of the equine palatine tonsil are similar to those of humans but differ from those of the lingual tonsil and are consistent with a role as an effector and inductor immunological organ.     

Distribution of the lingual lymphoid tissue in domestic ruminants

The distribution and organisation of the intralingual lymphoid tissue was studied in sheep, goat and cattle. For each species, the tongues of two animals were harvested and divided in sample blocks extending over the total surface of the tongue. With 2.5 mm intervals, ten serial histological sections were made for conventional histological staining (haematoxylin-eosin, Van Gieson, Masson's trichrome) and immunohistochemical staining of lymphoid cells (anti-CD3, anti-CD21, anti-CD45). Lymphocytes were scattered in the subepithelial propria-submucosa and in the connective tissue cores of the lingual papillae. The connective tissue cores of fungiform papillae, including those located on the lingual apex, and vallate papillae showed relatively more lymphocytes than the propria-submucosa. Lymphoid cell aggregations were even more abundant beneath the grooves surrounding the vallate papillae in small ruminants. In cattle, a well-organised lingual tonsil was additionally found at the root of the tongue. CD3-positive lymphocytes were observed in all species examined. CD21-positive lymphocytes were numerous in the lymphoid nodules of the bovine lingual tonsil but very scarce in the ovine and caprine tongues. Therefore, the lymphoid cell aggregations in the tongues of small ruminants should not be referred to by the term 'lingual tonsil'.     

Larynx-associated lymphoid tissue (LALT) in young cattle

This paper describes the presence of lymphoid tissue in the mucosa of the bovine larynx. A total of 15 bovine larynges were examined both macroscopically after tissue fixation in acetic acid and microscopically using histology. It was found that no paraepiglottic tonsil was present in cattle, although a few lymphoid follicles were present in the mucosa at the base of the epiglottis. This result is in accordance with previous reports. In contrast, numerous lymphoid follicles were seen in the mucosa of the epiglottis and the corniculate processes of the arytenoid cartilages. This suggests that larynx-associated lymphoid tissue is present in cattle. Our observation could be of clinical importance, e.g. in the framework of the development of aerosolized vaccines.     

Histology, immunohistochemistry and ultrastructure of the tonsil of the soft palate of the horse

The tonsil of the soft palate was an oval, flat structure located centro-rostrally on the oral surface of the soft palate. Its stratified squamous non-keratinized epithelium was perforated by holes or small crypts the deeper parts of which were loosely spongiform inter-digitated with lymphoid tissue. These unusual features have not previously been reported in tonsils of any species. Crypts and reticulated epithelium as found in the lingual and palatine tonsils were not observed. Lectins showed varying affinities for specific layers of the epithelium. M cells were not observed. A few Langerhans cells were distributed among surface epithelial cells. Lymphoid tissue was arranged loosely and in isolated lymphoid follicles in the subepithelial lamina propria mucosae. Although IgA+ cells and macrophages were proportionately more numerous the amount of lymphoid tissue was much less than in the lingual and palatine tonsils. Most of the follicular germinal centres lacked a darkly stained corona. CD4 positive were more numerous than CD8+ lymphocytes and were distributed in the parafollicular and inter-follicular areas. Large clusters of mucus acini positive for glycogen, acidic and neutral mucopolysaccharides separated lymphoid tissue from deeply placed striated muscle. Only a few high endothelial venules were observed in the parafollicular and inter-follicular areas. These had relatively few vesiculo vacuolar or other organelles in their high endothelial cells and few lymphocytes attaching to their walls.     

Comparison of sampling and isolation procedures for recovery of Yersinia enterocolitica serotype O:3 from the oral cavity of slaughter pigs

Yersinia enterocolitica serotype 0:3/biotype 4 was isolated from the oral cavity of altogether 32 (68.1 %) of 47 freshly eviscerated slaughter pigs. Most efficient recovery was achieved by cultivation of tissue samples from both tongue and tonsils of the same individual. The isolation rate so obtained was significantly higher than that obtained by separate examination of either tonsil swabs or tongue swabs. However, the isolation frequency achieved by combined swabbing of the 2 sites was not significantly different. In general, tonsils were more productive for the recovery of 0:3 strains than were tongues, and tissue samples yielded higher isolation rates than did swabs. Three-week cold enrichment in a low selective medium proved essential for optimal recovery. However, the highest number of isolates was obtained using a combination of methods, including direct plating and selective enrichment in a modified Rappaport broth in addition to cold enrichment.     

Cystic ectopic lingual thyroid tissue in a male cat

CASE DESCRIPTION-A 6-year-old neutered male cat was examined because of a 4-week history of abnormal sounds while drinking and a previously noted mass at the base of the tongue. CLINICAL FINDINGS-Oral examination revealed a 1-cm-diameter midline cystic mass on the dorsal aspect of the base of the tongue at the junction of the rostral two-thirds and caudal third of the tongue. Complete blood count and serum biochemical analysis revealed no clinically relevant abnormalities, and serum total thyroxine and free thyroxine (determined by equilibrium dialysis) concentrations were within the reference range. TREATMENT AND OUTCOME-The fluid in the cystic mass was aspirated, and the remaining deflated mass was marsupialized. Histologic and immunohistochemical examination of sections of the excised mass revealed ectopic thyroid tissue. The cat recovered uneventfully from the surgery, clinical signs resolved, and the cat remained euthyroid with no recurrence of the mass as of 8 months after surgery. CLINICAL RELEVANCE-This is the first known reported case of ectopic lingual thyroid tissue in a male cat. In humans, the most common site of ectopic thyroid tissue is at the base of the tongue and the condition is disproportionately found in females, compared with males. In humans with ectopic lingual thyroid tissue, the patient often lacks any other functional thyroid tissue. However, the cat of this report remained euthyroid after mass resection.     

山羊咽扁桃体和咽鼓管扁桃体的组织结构观察

选取健康10月龄奶山羊10头,断头宰杀后取咽扁桃体和咽鼓管扁桃体,应用组织学光镜和电镜制片技术研究咽扁桃体和咽鼓管扁桃体的显微和亚显微组织结构.结果表明:山羊咽扁桃体和咽鼓管扁桃体的黏膜上皮主要由2～3层多边形上皮细胞组成,部分区域只有单层扁平细胞,相邻上皮细胞间空隙很大,上皮细胞表面有丰富的微绒毛.上皮细胞之间和黏膜上皮下方固有层内有大量淋巴细胞浸润.扁桃体的实质部分由数个次级淋巴小结和弥散淋巴组织构成,弥散淋巴组织中有大量分布的淋巴管和毛细血管后微静脉.此外,在紧贴黏膜上皮细胞下方的固有层和淋巴滤泡中可观察到少量的树突状细胞.结果提示山羊的咽扁桃体和咽鼓管扁桃体可作为鼻腔免疫的主要诱导位点和效应部位.     

Lymphocyte populations and adhesion molecule expression in bovine tonsils

Bovine tonsils are mucosal-associated lymphoid tissue (MALT) located at the entry of the pharynx where both inhaled and ingested antigens can induce an immune response. This study was conducted to determine the lymphocyte populations and adhesion molecule expression in the palatine tonsil (PT) and pharyngeal tonsil (PhT) of adult cattle and compare them with typical MALT (discrete Peyer's patches, PP) and a peripheral lymph node (parotid lymph node, PLN). The distribution of various lymphocyte subsets was determined in situ by immunofluorescence, and their proportions were determined by multicolor flow cytometry. The tonsils were similar to PP in the proportions of B- and T-cells (25-32% T-cells, 39-45% B-cells), and T cell subpopulations (CD4, CD8, and gammadelta). The PP contained the highest proportion of memory T-helper cells with beta7 integrin (30.3%+/-5.4), the tonsils intermediate (PT: 19.8%+/-4.4 and PhT: 19.7%+/-4.9), and the PLN had the lowest proportion (15.4%+/-3.1). The opposite relationship was observed with CD62L on na?ve T- helper cells as PP had the lowest proportion (14.2%+/-6.4), the tonsils intermediate (PT: 17.4%+/-2.5 and PhT: 24.3%+/-7.3), and the PLN the highest proportion (45.3%+/-6.5). MAdCAM-1 was highly expressed in the high endothelial venules (HEV) of PP, with variable and weak expression in the tonsils and PLN. PNAd, on the other hand, was highly expressed in HEV of tonsils and PLN, and weakly expressed in the PP. These results indicate that the bovine tonsils share characteristics with both PP and PLN. The alpha4beta7/MadCAM-land CD62L/PNAd interaction may be involved in lymphocyte migration to the tonsils, but it is likely that other adhesion molecules participate as well. Similarities between the human and bovine tonsils suggest that cattle may provide a good model to study the role of the tonsil in the respiratory immune response.     

SEM and neurohistological observations of nerve endings in the middle region of the tongue of the collared peccary (Tayassu tajacu): a silver impregnation method

The presence of lingual papillae and the nerve endings in the middle region of the tongue mucosa of collared peccary (Tayassu tajacu) were studied using scanning electron microscopy and light microscopy, based upon the silver impregnation method. The middle region of tongue mucosa revealed numerous filiform and fungiform papillae. The thick epithelial layer showed epithelial cells and a dense connective tissue layer containing nerve fibre bundles and capillaries. The sensory nerve endings, intensely stained by silver impregnation, were usually non-encapsulated and extended into the connective tissue of the filiform and fungiform papillae very close to the epithelial cells. In some regions, the sensory nerves fibres formed a dense and complex network of fine fibrils. The presence of these nerve fibrils may characterize the mechanisms of transmission of sensitive impulses to the tongue mucosa.     

scanning electron microscopy of lingual papillae in the common shrew, Sorex araneus, L

The dorsal surface of the tongue of the adult common shrew (Sorex araneus L.) was examined by scanning electron microscopy. As in the other insectivores, three types of lingual papillae were observed: filiform, fungiform and vallate papillae. The filiform papillae represented the most numerous type of lingual papillae. The characteristic feature of the filiform papillae, covering the apex and corpus of the tongue, is the two processes tilted to the root of the tongue. The filiform papillae on the lingual apex are reduced in size and structure. Five to six fungiform papillae are placed symmetrically along the left and right border of the corpus of the tongue. Two large oval vallate papillae are located on the radix of the tongue. The posterior surface of the tongue in common shrew is covered with a smooth mucosa with the openings of the serous glands.     

Colonization of the tonsils of calves with Pasteurella haemolytica.

Tonsils of 10 calves were inoculated with Pasteurella haemolytica (PH) and the degree of colonization was followed by collecting sequential tonsil. wash specimens. Tonsils were colonized for at least 3 weeks after instillation of PH into the tonsillar sinus. Calves with colonized tonsils responded with serum and nasal secretion antibody responses to PH and to leukotoxin. Pasteurella haemolytica was detected in nasal mucus specimens of 2 calves during the week after inoculation of the tonsils, but all other specimens were culture-negative. Infectious bovine rhinotracheitis virus-induced respiratory tract disease 25 days later did not elicit a population increase of PH in the tonsils, and did not elicit shedding of PH in nasal mucus.