FBS, US Origin is collected from a U.S.D.A. regulated and monitored abattoir by technicians who work "on-site" where the fetal blood is aseptically collected via cardiac puncture. This raw material is transported to the production facility where it undergoes sterilization via filtration through multiple 0.1 micron filters. The care and diligence taken in handling the fetal serum minimizes cell lysis and other detrimental factors thereby reducing possible lysozyme and hemoglobin contamination. This translates into increased performance in the final product. It is superior for hybridoma cloning. It is supplied sterile, with no detectable mycoplasma or viral infection. Serum is an extremely complex mixture of many small and large biomolecules with different, physiologically balanced growth-promoting and growth inhibiting activities.