Morphological investigations into the structure of frozen-thawed rat islets of Langerhans

Fetal rat pancreases, cultured for 8 days in RPMI 1640, were successively frozen to -196 degrees C. The samples, defrosted at different intervals (0, 5, 1, 2, 7, and 15 days), were examined by TEM and SEM. The effects of culture, various cooling times, warming rates, thawing procedures, dimethyl sulfoxide concentration, and ultrastructural features of cellular elements were analyzed.