Disruption of spermatogenesis in rabbits consuming ethylene glycol monomethyl ether

Effects of ethylene glycol monomethyl ether (EGME) on spermatogenesis were examined using groups of six to seven Dutch rabbits that received 0, 12.5, 25.0, 37.5, or 50.0 mg of EGME/kg body weight, respectively, in their drinking water 5d/week. After 12 weeks, animals were euthanized and their testes were removed, weighed, and processed to permit germ cell numbers to be quantified. Spermatogenesis was depressed by EGME in a dose-dependent manner; numbers of round spermatids per Sertoli cell (a measure of spermatogenic efficiency) averaged 8.86, 8.87, 6.20, 2.38, and 7.42 for the 0, 12.5, 25.0, 37.5, and 50.0 mg/kg dosages, respectively. The latter value of 7.42 represents an overestimation of sperm production because it is based on only two unexpected outlier rabbits. Nearly complete destruction of spermatogenesis occurred in the other five animals in this highest dosage group, precluding evaluation by the histometric method. Numbers of homogenization-resistant elongated spermatids per testis, measurable on all animals, averaged 231, 256, 195, 52, and 67 x 10(6), respectively. The correlation between the predicted sperm production, based on the elongated spermatids at necropsy, and the number of sperm ejaculated by the males during week 12 was 0.92. Thus, EGME impaired rabbit spermatogenesis in a dose-dependent manner. Generally, rabbit spermatogenesis was at least 10 times more sensitive to EGME than previously reported for rats and mice.