Age-related histomorphometric and immunohistochemical changes of the moderator band in Egyptian Baladi cattle

The moderator band (MB) is a common fibromuscular anatomical structure for the right ventricle of most animals. The histomorphometric and immunohistochemical analysis of the MBs of Egyptian Baladi cattle in relation to age was the aim of this study. Eighteen clinically healthy animals of both sexes were used for this study. The animals were divided into three groups depending on age, group I (N = 4, <1 year), group II (N = 8, 1-2 years) and group III (N = 6, 4-8 years). Cross sections of the MBs from all groups were stained with H&E, Masson's trichrome and anti-connexin43 (Cx43) antibody for histological and immunohistochemical examinations. Also, measurements for the thickness of the endocardium of the MB as well as, the wall of its muscular artery were conducted. Bundles of Purkinje fibres (PFs) were identified peripherally in the endocardial layer and among the myocardial fibres in the core of each MB. The infiltration of endocardial adipocytes was the characteristic for MBs of old animals. All morphometric data showed a significant increase with the advancement of age. Immunohistochemical findings revealed the localization and distribution of Cx43 in the PFs and intercalated discs of all examined MBs. However, variation of Cx43 immunoreactivity was found among the groups depending on the age. On the basis of this study, this conclusion of different histomorphometry and Cx43 expression of the MBs in relation to age was drawn. These interesting findings provide further insight into age-related physiological and pathological heart conditions.