Polyfunctional cross-linking of polydisperse copolymer primary chains is described theoretically, and dependences of structural parameters on conversion (alpha) before and after the gel point are derived. In particular, concentrations and average molecular weights of the sol, the elastically active network chains and their backbone chains, and dangling chains are given as functions of alpha. The theory can be used for chemical as well as physical gelation processes. A generalized theory of branching processes (TBP) is used, in which two sets of variables are introduced, for units and for links.