The Endometrium of the Anoestrous Female Pig: Studies on Infiltration by Cells of the Immune System

The aim of this study was to investigate the distribution of immune cells in the endometrium of anoestrous female pigs, five sows in anoestrus by lactation and five pre-pubertal gilts (Swedish Landrace x Swedish Yorkshire). Uterine samples, taken immediately after slaughter, were fixed, embedded in plastic resin and stained with toluidine blue or cryo fixed and stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method. Immune cells in the surface (luminal) and the glandular epithelium as well as the subepithelial and the glandular connective tissue layers were counted using light microscopy. In the surface (luminal) and the glandular epithelia of gilts and sows, lymphocytes were the predominant immune cells found. There were no significant differences between gilts and sows. Macrophages were detected in the glandular epithelium of sows but not in gilts. In the subepithelial and the glandular connective tissue layers of both gilts and sows, lymphocytes were also the most common immune cells found. The numbers of lymphocytes and macrophages were significantly higher in the sows than in the gilts (p