Expression Of Mhc-ⅱ, Mhc-ⅰ, α-SMA, Pax7 And Pax3 In The Muscular Layer Of The Pharynx And Esophagus Of Dogs And Human Foetus

Objective: To investigate the spatial distribution of MHC-Ⅱ, MHC-Ⅰ,α-SMA, Pax7 and Pax3 in the muscular layer of the pharynx and esophagus of the healthy adult dogs and human foetus.Methods: A total of 6 adult dogs and three human foetus were used in this study. The pharynx and esophagus were collected from each dog and each human foetus. The specimens were examined with histology and immunohistochemistry techniques using anti-MHC-Ⅱ,anti-MHC-Ⅰ,anti-α-SMA,Pax7 and Pax3 antibodies.Results: (1) The muscular layer of the whole pharynx and esophagus in adult dogs expresses the MHC-II isoform, but its intensity is gradually decreased from rostral to caudal in the esophagus. (2) MHC-Ⅰwas expressed in the muscular layer of the lower pharynx and esophagus in adult dogs, including the abdominal segment of the esophagus, but its intensity is gradually increased from rostral to caudal in the esophagus. (3) The expression of a-SMA of the adult dog is initiated in the inner muscular layer in the lower middle segment of the esophagus and its intensity then gradually increased towards the caudal end of the esophagus and also expanded to the outer muscular layer. (4) Pax7 and Pax3 were not detected in the muscular layer of the pharynx and esophagus in audlt dogs. (5) MHC-Ⅱ, MHC-Ⅰa nd Pax7 were always co-localized and dominant in the external longitudinal muscular layer of the pharynx and esophagus in human foetus, and gradually disappeared at the inferior end of the esophagus. (6) In human foetus,α-SMA expression was detected in the most inner muscular layer at the upper end of the esophagus and then gradually increased downward and outward. The muscle fibers expressingα-SMA were mainly circularly orientated. (7) Pax3 was not detected in the muscular layer of the pharynx and esophagus in human foetus.Conclusion: (1) This study precisely identified the transition zone between skeletal muscle and smooth muscle of the esophagus in adult dogs. (2) The distribution of MHC-II and MHC-I in the muscular layer of the pharynx and esophagus in adult dogs were well investigated. (3) Pax7 and Pax3 were not detected in the muscular layer of the pharynx and esophagus in adult dogs. (4) The distribution of MHC-II, MHC-I,α-SMA, Pax7 and Pax3 in the muscular layer of the pharynx and esophagus in adult dogs or human fetus were well investigated.