The final step in the preparation of tissue culture labware is sterilization. Currently, most labware is sterilized using gamma irradiation. Vessels are packaged in polymer bags and corrugated cases prior to irradiation. Since excessive radiation can degrade the tissue culture surface, dose levels are carefully monitored. Flask Tissue culture flasks come in a variety of sizes ranging from 12.5 cm 2 to 300 cm 2 .
Most flasks are available with either straight or angled necks.
Angled necks allow easier access to the entire growth surface, help prevent media from reaching the cap, and allow media to be poured from the flask with less dripping. Vented caps feature a hydrophobic membrane that permits sterile gas exchange when the cap is closed. BD Biosciences' line of flasks is available nontreated, tissue culture treated, or with the Primaria surface. The Primaria surface is recommended for adherent cultures that do not grow on standard tissue culture-treated surfaces. Color-coded covers can be placed on vented caps to prevent changes in pH upon removal of the flask from the CO 2 incubator.