The penetration of chromium-EDTA from blood plasma into various compartments of rat testes as an indicator of function of the blood-testis barrier after exposure of the testes to heat.

The concentration of chromium51-EDTA in blood plasma after an intravenous infusion was found to be about 40 times that present in rete testis fluid and 20 times that in the additional seminiferous tubular fluid resulting from ligation of the efferent ducts. These values indicate the effectiveness of the blood-testis barrier to small water-soluble molecules, like Cr-EDTA. The volume of distribution in microlitres of Cr-EDTA in the parenchyma was about 60% of the volume of the interstitial tissue as determined on frozen sections by morphometry, and was similar, or slightly less, in the ligated testes, compared with the unligated testes. Heating the testes to 43 degrees C for 30 min led to the expected reduction several days later in testis mass, but the volume of distribution of Cr-EDTA was no greater than that in the testes of control rats, and the ratio of Cr-EDTA space to interstitial tissue was not different, while the concentration of Cr-EDTA in the additional seminiferous tubular fluid increased only slightly as testis mass fell. These results indicate that the blood-testis barrier was only slightly less effective, if changed at all, during the period of spermatogenic disruption following local heating of the testis.