Scanning electron microscopy of the luminal epithelium of the mouse uterus

Four methods of manipulating mouse uterine tissue during fixation, preparatory to examination of the luminal epithelium by scanning electron microscopy (S.E.M.), are described and the results assessed. The appearance of the epithelium varies according to the technique used, the choice of method depending on the type of information required from the S.E.M. study. Surface topography is preserved in a condition most closely resembling that of fresh tissue by opening the uterus and fixing the tissue flat. Critical examination of cellular and subcellular surface detail, however, depends on adequate spreading of the epithelial layer during fixation by distension of the uterine lumen under positive pressure. The method of tissue manipulation has a more profound effect on the appearance of the sample than any of the dehydration techniques which follow. For routine S.E.M. examinations at medium magnifications (smaller than X10,000), specimens which were air dried from alcohol, acetone or ether, or freeze dried, gave satisfactory results. Air drying from amyl acetate, and CO2 critical-point drying gave superior results at higher magnifications (greater than X10,000) with better preservation of individual microvilli.