[en] The dominant feature of photonuclear reactions at intermediate energies is the excitation of the δ resonance and one can therefore use such reactions to study the dynamics of δ propagation in a nucleus. Following an introductory section the author comments on photoabsorption on a single nucleon in Section II. A review of the δ-n Greens function and of the photonuclear amplitude is given in Section III. Results for photoabsorption on ₄He are shown in Section IV and compared with the data. Coherent π₀ photoproduction is discussed in Section V and calculations for ₁₂C are compared to recent measurements. (Auth.)