[en] The microscopic origin of the strangeness enhancements observed in PbPb collisions at the SPS is studied by testing the effects of three mechanisms. First, the junction processes found in the HIJING/BB event generator are reviewed showing that they can account for only part of the observed hyperon enhancements. Second, the efficient final state chemical changing processes (e.g. Λ+K ↔ Θ+π) are included by adding the General Cascade Program (GCP) to HIJING/BB. While these processes are shown to further enhance multistrange baryon production, HIJING/BB+GCP is still unable to fully describe either the large hyperon yields or the increasing K⁺/π⁺ ratio. Finally, the addition of transient field fluctuations or ropes to HIJING/BB+GCP is shown to be needed to account for the large hyperon yields and for the behaviour of the K⁺/π⁺ ratio. (author)