Amount of tissue range could not be more than 75 mg per 1 ml TRIzol reagent. - Put tissue in 1.8 ml Cryo.s tube already filled with 1ml TRIzol reagent. - Cut the tissue with scissors into small pieces as possible. - Homogenize it two times 2 minutes at max speed, in between incubate it 1 min. on ice (If the tissue contains fat homogenize it 1 min. more), and then transfer it to 2 ml eppendorf. - Centrifuge it 10 min. 12000 xg at 2-8 C. - Transfer the supernatant to a new 2 ml eppendorf. - Incubate 5 min 15-30 C. - Add 0.2 ml Chloroform per 1 ml TRIzol. - Shake by hand 15 sec. - Incubate it 2-3 min. at 15-30 C. - Centrifuge it 12000= xg 15 min at 2-8 C. - Transfer colorless upper aqueous phase (about 60% of the tube) to a new 1.5 ml eppendorf tube. - Precipitate RNA with 0.5 ml isopropyl alcohol per 1 ml TRIzol reagent, mix well by pipetting. - Incubate it 10 min at 15-30 C. - Centrifuge it 12000= xg 10min at 2-8 C. - Remove the supernatant and wash RNA pellet 75% Ethanol per 1 ml TRIzol reagent, - Mix the sample by vortexing 15-30 sec. - Centrifuge it 7500xg 5 min at 2-8 C ( If it is not enough, spin it couple of minutes more). - Remove Ethanol, let the RNA pellet dry 4-6 minutes ( RNA pellet has to be visible at the end of the drying otherwise it is not possible to dissolve the RNA properly again. - If high concentration is favorable dissolve the RNA in 30 (l DEPC threatened H2O (The initial amount of tissue must be higher than 20 mg, If less dissolve in 20 (l DEPC threatened H2O, and then incubate the sample at 55 C for 5 min. either in a water-bath or dry thermomixer.) It is also possible to dissolve and keep the extracted total RNA in 0.5% SDS or 100% formamide.