TOTAL NUMBER OF IMMUNOCOMPETENT CELLS IN THE NORMAL RAT EPIDIDYMIS AND AFTER VASECTOMY

The aim of this study was to make unbiased quantitative estimates of t he number of T8 cytotoxic cells and T4 helper cells and macrophages in the head and tail of rat epididymides, using newly developed design-b ased stereological methods in fertile control animals, and to compare these with results from vasectomized animals. The location of these ce lls within the intra- and interepithelial compartments of the epididym is was also studied. In control animals, both the T4 helper cells and macrophages and T8 cytotoxic cells were found in significantly higher numbers (P < 0.01) in the head interepithelial location than in the in traepithelial site. In addition, there were significantly more (P < 0. 01) T8 cytotoxic cells in the tail interepithelial region. Within the head region of vasectomized rats, there was a significant increase in T8 cytotoxic cells in the intraepithelial location (P < 0.01), and a d ecrease in T4 helper cells and macrophages in the interepithelial regi on (P < 0.05). Serum samples from vasectomized animals, when compared with those from control animals, showed a significant increase in cyto toxic antisperm antibody. This suggests that, in response to the incre ased spermatozoal antigenic absorption that takes place in the epididy mis after vasectomy, the immune system redistributes its T cell subset s to modify the immune tolerance that may occur.