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.