Examination of the Reticular Epithelium of the Bovine Pharyngeal Tonsil

Abstract

The pharyngeal tonsil (adenoid), located at the posterior of the nasopharynx is ideally positioned to sample antigens passing through the nasal cavity or oral cavity. Entering antigens will first contact tonsilar epithelium. To better understand the cellular organization of this important epithelial layer, pharyngeal tonsils were collected from six, 7-month-old calves and examined by light microscopy, immunohistochemistry, and electron microscopy. Morphometric analysis showed that the epithelium overlying lymphoid follicles (reticular epithelium) contained significantly more B-cells, CD4þ, and CD11cþ cells than nonreticular epithelium. In contrast, nonreticular epithelium contained significantly more, c/d TCRþ cells than reticular epithelium. Scanning and transmission electron microscopy of reticular epithelium identified a heterogeneous population of epithelial cells, many of which displayed morphologic characteristics of M-cells. Moreover, putative M-cells were shown to possess the capacity for microparticle uptake. Bovine pharyngeal tonsilar reticular epithelium contains key immune cells, as well as M-cells; elements essential for antigen uptake, antigen processing, and initiation of immune responses. A better understanding of the morphology and function of tonsilar lymphoepithelium will strengthen our understanding of it's role in disease pathogenesis, and potential use as an induction site for mucosal immune responses to vaccination. Anat Rec, 294:1939Rec, 294: -1950Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

Histology, histochemistry and ultrastructure of the nasopharyngeal tonsil of the buffalo (Bubalus bubalis)

“…The tonsillar mucosa was covered by pseudostratified columnar ciliated epithelium having goblet cells (Figure a–d), a feature consistent with observations in small ruminants (Kumar et al, ; Kumar & Nagpal, ), dog (Billen, Peeters, Dehard, Day, & Clercx, ; Casteleyn, Breugelmans, Simoens, & Broeck, ), pig (Liu, Yu, Li, & Yang, ; Ranjit et al, ), horse (Kumar & Timoney, ; Kumar et al, ) and bovine (Palmer et al, ). However, a squamous epithelium (Achaaban, Mouloud, Tligui, & Allali, ) has been reported in the camel (Yang, Yuan, Xu, Shoa, & Wang, ).…”

“…The tonsil also shows similarities with lymph nodes and may, in addition, participate as effector organ of local and systemic adaptive humoral immunity (Brandtzaeg, ). However, despite their immune function, tonsils as well play a major role in disease pathogenesis in domestic animals (Palmer, Stasko, Ray Waters, & Thacker, ; Zidan & Pabst, ) by serving as route of entry and colonization for many pathogens (Timoney & Kumar, ). The anatomical features of the nasopharyngeal tonsil have been extensively studied in the horse (Kumar & Timoney, ; Kumar, Timoney, & Sheoran, ), small ruminants (Casteleyn, Broeck, & Simoens, ; Casteleyn, Simoens, Cornillie, & Broeck, ; Kumar, Kumar, & Kumar, ; Kumar & Nagpal, ) and pigs (Ranjit , Kumar, & Singh, ).…”

Yak (Bos grunniens) Tonsils: Morphological Description and Expression of IgA and IgG

“…Interestingly, in some parts of the pharyngeal tonsil, a few lymphoid follicles and scattered lymphoid cells were covered by a non‐keratinized stratified squamous epithelium, which was related to their particular location. It was in agreement with the findings in cattle (Palmer et al, ). Significantly, adult yak tonsils had the primary and secondary lymphoid follicles.…”

“…In cattle tuberculosis (Cassidy et al, 1999), and cattle spongiform encephalopathy (Caramelli et al, 2003;Wells et al, 2005), tonsils are strategic entry points for pathogens. Therefore, increasing researchers to enter the field of mucosal immunology were interested in the morphological characteristics of tonsils in various species, including the humans (Nave et al, 2001;Idris et al, 2013;Jovi c et al, 2015), ovine (Cocquyt et al, 2005;Casteleyn et al, 2007Casteleyn et al, , 2008Casteleyn et al, , 2010, camels (Zidan and Reinhard, 2009;Jia et al, 2017), cattles (Manesse et al, 1998;Velinova et al, 2001;Palmer et al, 2009Palmer et al, , 2011Zidan and Pabst, 2011), pigs (Belz and Heath, 1996;Williams and Rowland, 1972;Liu et al, 2012), horses (Kumar and Timoney, 2005), dogs Heath, 1995a, 1995b), and rabbits (Harrison et al, 1970;Oláh and Everett, 1975). Unfortunately, as a special plateau animal, there are no detailed anatomical or histological dates of yak tonsils.…”

Age‐related changes in the morphology and the distribution of IgA and IgG in the pharyngeal tonsils of yaks (Bos grunniens)

“…Interestingly, the epithelium overlying the pharyngeal tonsil is composed of the nonreticular epithelium and the reticular epithelium. Among them, the reticular epithelium is not only a site of antigen uptake and transport by M‐cells, but also a network of antigen processing and presenting cells capable of initiating a host immune response (Kraehenbuhl & Neutra, ; Palmer et al, ). This epithelial barrier also samples and translocates antigens to the underlying lymphoid tissue (Perry & Whyte, ).…”