Scanning electron microscopy of the endometrium of mares infused with gentamicin

Scanning electron microscopy (SEM) was used to study the endometrium of nine 1-year-old thoroughbred mares after twice intrauterine infusions of gentamicin, on 2 consecutive days. Five mares were infused on 2 consecutive days with 40 ml gentamicin (50 mg/ml) mixed with 80 ml of normal saline. Four mares served as controls and were infused with 120 ml of saline on 2 consecutive days. Endometrial biopsies were obtained from all mares 3 days after the second intrauterine infusion. Each biopsy was processed for SEM by standard methods. The endometrial epithelium of the gentamicin-infused mares had more cellular perforations than the saline-infused mares. The gentamicin-infused mares had less and shorter microvilli. The ciliated cells were fewer and some ciliated cells had disrupted and some had drooping cilia. The endometrial epithelium of the gentamicin-infused mares had a considerable number of endometrial cells that lost their luminal surfaces and some that lost their microvilli, compared to the saline-infused mares. We suggest that the information gathered in this pilot study should be used as basis for further investigation, on a larger scale basis, of the effects of repeated intrauterine infusion of gentamicin on the endometrial mucosa of mares.