The product C4243 is a sterile-filtered bovine skin collagen solution suitable for cell culture. It is prepared from type I bovine collagen, following the nomenclature proposed by Bornstein and Traub.
The caution regarding the confusion of Sigma-type designations with recognized collagen classification types refers to specific examples such as Cat # C3657, which is listed as (Sigma Type IX) but is actually Collagen from human placenta Bornstein and Traub Type V, based on literature-based classification. Type IX is an internal classification used by Sigma.