Induction of Langerhans' cell mitosis in vivo after orchiectomy on mice

We recently reported that male mice have fewer Langerhans' cells (LCs) than females and that orchiectomy resulted in an increased LC density. In this study we demonstrate that orchiectomy induces a transient increase in the number of paired LCs (PLCs) before the increase in LC density occurs. The results of double staining for adenosine triphosphatase (ATPase) and 5-bromo-2'-deoxyuridine (BrdU) showed that all examined PLCs had incorporated the intraperitoneally injected BrdU, while only 0.7% of the unpaired LCs were BrdU-positive; that supported the notion of PLCs as being divided daughter LCs. Orchiectomy appears to induce a transient increase in mitotic activity of LCs resulting in the increased LC density.