PREPARATION OF TISSUES FOR LOCALIZATION OF SEX HORMONES BY AUTORADIOGRAPHY .2. LOSS OF RADIOACTIVE MATERIAL IN EMBEDDING MEDIA AFTER FREEZE DRYING AND VAPOUR FIXATION OF TISSUES

Tissues of rats given tritium labelled oestradiol, progesterone and testosterone were freeze dried and fixed in formaldehyde and osmium tetroxide vapour. The loss of radioactive material during infiltration in non-accelerated methacrylate and Epon was measured. In addition, the extraction during the floating of the sections on water following sectioning, and during the mounting of the sections and the application of the autoradiographic stripping film was examined. Very small amounts of radioactive material were extracted both in methacrylate and Epon following fixation with osmium tetroxide vapour. After formaldehyde vapour fixation, the loss was of the same order as that registered during embedding of the unfixed tissue. Significantly more radioactive material was lost from pituitary and uterine tissue than from liver. When uterine tissue of rats given 3H-oestradiol was infiltrated in Epon at 50°C for 48 hours following osmium tetroxide vapour fixation, 1.53 per cent of the radioactive material was registered in the embedding medium. From anterior pituitary tissue, 3.34 per cent was lost. A noticeable amount of radioactive material was also lost when the tissue sections were in contact with water. The test experiments showed that 2.57±0.97 per cent of the radioactive oestrogens of uterine tissue of rats given 3H-oestradiol was extracted. The validity of the observations and various sources of error are discussed. © 1969 Springer-Verlag.