AbstractA simple method leading to growth and mitosis in over 95% of shortterm cultures of lymphocytes from the blood, lymph or thymus of the rat is described. The method which is modified from Moorhead's original technique (′60) employs standard tissue culture medium (Eagles MEM or TC no. 199), 20% fresh rat serum, washed lymphocytes, penicillin, and phytohemagglutinin‐P (0.01 cm3/cm3of culture of a 1:5 dilution of stock solution). Details of culture technique and factors contributing to growth failures are discussed.The chromosomes of male and female Lewis rats were studied in metaphase spreads of cultured cells. The karyotypes of these rats are presented and found to be in agreement with those recently reported by Hungerford and Nowell (
展开▼