Evidence for the control of testicular interstitial fluid volume in the rat by specific germ cell types

Following on from our recent evidence that Sertoli cells may regulate testicular interstitial fluid (IF) volume, this study has assessed whether depletion of specific germ cell types in vivo is associated with changes in recovered IF volume. Germ cell depletion was induced by either a single oral administration of 650 mg methoxyacetic acid (MAA)/kg or exposure of the testes to local heating (43 degrees C for 30 min). Treatment with MAA induced depletion or loss of most pachytene and later spermatocytes at 1-3 days and, because of maturation depletion, this resulted in the specific depletion of later germ cell types at 7-35 days. Testicular IF volume was unchanged at 1-7 days after MAA treatment but was increased significantly (P less than 0.01) at 14 days and was nearly doubled (P less than 0.001) at 21 days, before returning to control levels at 28-42 days. Serum LH (and FSH) levels were generally higher in MAA-treated rats, especially at 21 and 28 days, but there was no obvious correlation between LH levels and IF volume changes. Similarly, there was no relationship between IF volume changes and testicular weight or IF levels of testosterone. The increase in IF volume at 14-21 days after MAA treatment coincided with specific depletion of the later elongate spermatids (steps 14-19) and, when these cells reappeared in the testis, IF volume normalized. This possible causal association was studied further in rats exposed to local testicular heating which, within 3 days, caused major depletion of pachytene spermatocytes and early (step 1-8) spermatids.(ABSTRACT TRUNCATED AT 250 WORDS)