The Investigation On Nasopharynx-associated Lymphoid Tissue Of Bama Minipigs

Intranasal immunization plays an important role in the prevention of infectious respiratory diseases.With increase of infectious respiratory diseases in pig,the research of intranasal immunization has been widely carried out.But there was less study of the pig’s nasal structure.Although the nasal structure of mice,rats and rabbits has been studied well,the anatomical and histological structures of these animals are very different from those of pigs.The anatomy and physiology of the porcine respiratory tract are more similar to humans,so it will provide a theoretical basis for human intranasal immunization by study of the pig’s nasal structure.Bama minipig(Sus scrofa domestica)is a miniature breed of pig and suitable for nasal cavity structure research.In this study,we characterized the features of the nasal mucosa of Bama minipigs via histological analysis.The nasal cavity of Bama minipigs can be divided into three parts:the regio vestibularis(Ⅰ,Ⅱ),regio respiratoria(Ⅲ,IV),and regio olfactoria(Ⅴ).The egio vestibularis of the nasal cavity was covered predominantly by stratified squamous epithelia;The regio respiratoria of the nasal cavity,where lymphatic tissues were random located,was covered predominantly by pseudostratified columnar ciliated epithelia.The regio olfactoria of the nasal cavity was covered predominantly by olfactory epithelium,nasopharynx-associated lymphoid tissues(NALTs)was located in the roof of the nasopharyngeal meatus and was continuous with the lymphoid tissue of the pharynx.The distribution of CD3+ T cells,immunoglobulin A(IgA)+ cells,M cells,and dendritic cells(DCs)increased distally in the nasal cavity.Goblet cells were mainly located in the middle nasal cavity.The present work comprises a histological study of the nasal cavity of Bama minipigs,and will be beneficial for understanding the mechanisms of immunity in these animals after nasal vaccination.Our research is divided into the following three parts in detail:1.Structure of the nasal cavity of Bama minipigsFour healthy,2.5-month-old Bama minipigs were collected.Their nose were selected five cross-sectional blocks(Ⅰ,Ⅱ,Ⅲ,Ⅳ and Ⅴ)perpendicular to the sagittal plane,the anatomical structure of nasal cavity was observed under the solid microscope.The nose blocks were fixed in Bouin’s fluid,decalcified,embedded in paraffin and making slices.Cross-sectional sections were stained with hematoxylin-eosin(HE).The nasal cavity of Bama minipigs can be divided into three parts:the regio vestibularis(Ⅰ,Ⅱ)covered by stratified squamous epithelia,the regio respiratoria(Ⅲ,Ⅳ)covered by pseudostratified columnar ciliated epithelia,and regio olfactoria(Ⅴ)covered by olfactory epithelium.Capillary vessels and glands were distributed abundantly in the lamina propria,lymphoid tissue was randomly distributed in the nasal cavity.NALTs was located in the roof of the nasopharyngeal meatus and was continuous with the lymphoid tissue of the pharynx.2.The distribution of immunocompetent cells in the nasal cavity of Bama minipigsThe propose of this study was to investigate the distribution of CD3+ T cells,IgA+cells,M cells,and goblet cells in the nasal cavity of Bama minipigs.CD3+ T cells,IgA+cells,and M cells were detected by immunohistochemistry,while goblet cells were determined by periodic acid-Schiff(PAS)staining.The number of CD3+ T cells in the cross section(cs)Ⅴ of nasal cavity were observed more than csIV(P<0.05);The number of CD3+ T cells in csIV were observed more than csⅡ and Ⅲ(O<0.05);In csl of nasal cavity,rare CD3+ T cells was observed.The number of IgA+ cells in the csV of nasal cavity were observed more than csⅢ(P<0.05);The number of IgA+ cells in the csⅢ of nasal cavity were observed more than csl and Ⅱ(P<0.05).The number of M cells in the csV of nasal cavity were observed more than csⅢ and IV(P<0.05);The number of M cells in the csⅢ and Ⅳ of nasal cavity were observed more than cs Ⅱ(P<0.05).The number of goblet cells in the cs Ⅱ and Ⅲ of nasal cavity were observed more than cs Ⅳand Ⅴ(P<0.05);In csⅠ of nasal cavity,rare goblet cells was observed.In conclusion,the distribution of CD3+ T cells,immunoglobulin A(IgA)+ cells,M cells,and DCs increased distally in the nasal cavity.Goblet cells were mainly located in the middle nasal cavity.3.The distribution of DCs in the nasal cavity of Bama minipigsThe propose of this study was to investigate the distribution of DCs in the nasal cavity of Bama minipigs.Four healthy,2.5-month-old Bama minipigs were collected.The MHCⅡ+ SWC3a+ DCs were detected by immunofluorescence.The number of MHCⅡ+SWC3a+DCs in the cross section(cs)Ⅴ of nasal cavity were observed more than cs Ⅲ(P<0.05);The number of MHCⅡ+ SWC3a+DCs in cs Ⅲ were observed more than csⅠ andⅡ(P<0.05);In csⅠ of nasal cavity,rare MHCⅡ+ SWC3a+DCs was observed.MHCⅡ+SWC3atDCs were mainly located in the middle and rear parts of nasal cavity.