Résumé
The evolution of primordial molecules in a context of gravitational collapse is investigated. From the abundances arising from inhomogeneous nucleosynthesis models (Omega(o) = Omega(b) = 1, H-o = 100 h Km s(-1) Mpc(-1) and 0.3 < h < 1; baryonic Einstein-de Sitter Universe with no dark matter), we present the basic processes of physics and chemistry in a simple model of a collapsing protocloud after the recombination epoch. II is found that the abundances of primordial molecules in such protoclouds can be modified, then these molecules will be susceptible of significant effects on the Cosmic Microwave Background (CMB) that we briefly discuss.