Abstract: A platelet freezing bag made of pliable plastic material has two needle ports designed to accept a syringe needle for transferring platelet concentrate and diluent plasma into the bag and a large draining port. The ports are protected and closed by pull-apart seals. The draining port is separated from the platelet receiving compartment by a push-apart seal which can be opened by exerting gentle pressure on the contents of the bag.

Abstract: An inexpensive, statically controlled cooling rate device comprising a cassette of metal plates and cardboard insulation in a plastic bag was used to freeze platelets in liquid nitrogen with glycerol-glucose as cryoprotectant. Depending on the thermocouple location, the cooling rate in the freezing bag varied between 22.1.degree. and 38.6.degree. C. per minute, averaging 33.6.degree..+-.1.1.degree. C. per minute at the center. The post-thaw recovery of platelets frozen with this device and reconstituted in plasma averaged 88.6.+-.11.7 percent, compared to 86.1.+-.9.9 percent for nonfrozen but identically processed platelets. [.sup.14 C]Serotonin uptake after 0.5-hour incubation was 95.9.+-.1.9 percent for fresh platelets in platelet-rich plasma, 92.7.+-.4.4 percent for nonfrozen processed platelets, and 81.4.+-.11.8 percent for frozen platelets, increasing to 85.9.+-.7.7 percent after one-hour incubation.