DECREASED NUMBER AND SIZE AND THE DEFECTIVE FUNCTION OF TESTICULAR MACROPHAGES IN LONG-TERM HYPOPHYSECTOMIZED RATS ARE REVERSED BY TREATMENT WITH HUMAN GONADOTROPINS

Macrophages are a common cell type in the testicular interstitium of t he rat and are morphologically and functionally related to Leydig cell s. We investigated the number of macrophages and Leydig cells in long- term. (24 weeks) hypophysectomized (LTHX) or sham-operated rats. LTHX rats showed a 76% decrease in the number of macrophages, whereas the n umber of Leydig cells was only slightlydecreased (by 18%). The profile areas of both macrophages and Leydig cells were very much decreased ( 46% and 66% respectively). Sham-operated and LTHX rats were heated wit h vehicle or human FSH and LH (hFSH/hLH; 75 IU/kg body weight per day) for 1 week. This treatment induced a 286%increase in the number of ma crophages and a 32% increase in the number of Leydig cells in LTHX rat s. The profile areas of macrophages and Leydig cells werealso increase d (212% and 184% respectively). About 80% of macrophages showed vacuol ization of the cytoplasm. Gonadotrophin treatment did not induce chang esin cell numbers in sham-operated animals but about 30% of macrophage s showed large cytoplasmic vacuoles. Vehicle- or hormone-treated LTHX rats were given a single injection of ethylene dimethane sulphonate (E DS) and killed 72 h later. Leydig cells were absent from the testicula r interstitium of sham-operated rats but there were large numbers of d ead Leydig cells (about 40% of the pre-existing population) in the tes ticular interstitium of LTHX rats 3 days after EDS treatment. Complete clearance of the testicular interstitium from EDS-killed Leydig cells was found in LTHX rats treated with hFSH/hLH. These results indicate that the decreased number and size and the defective function of testi cular macrophages in LTHX ratscan be restored by treatment with gonado trophins.