MAMMARY-GLAND WHOLE MOUNT TECHNIQUE THAT PRESERVES CELL FINE-STRUCTURE FOR ELECTRON-MICROSCOPY

A mammary gland whole mount technique has been developed that preserves cell fine structure and makes it possible to also examine the preparations by electron microscopy. The glands are placed on glass microscope slides, fixed in a paraformaldehyde-glutaraldehyde mixture, defatted in acetone, stained with 0.5% methylene blue (or trypan blue) in saline, and dehydrated in ethanol. They are evaluated and photographed in 100% ethanol. Then specific areas (i.e. containing small growths, tumors, or other lesions) are selected, excised and prepared for electron microscopy. An alternate procedure is to embed the whole gland for electron microscopy. The ultrastructural preservation is good, organelles are evident and there is no observable dye precipitate. The only unusual finding is that cell membranes display a 'negative' image.