Cosmic strings, i.e. linear topological defects which are expected to form during the Spontaneous Symmetry Breaking of a Grand Unified Theory (GUT), permit to probe particle physics up to energies around 10^16 GeV. Until now, only toy-models have been used to describe these strings, assuming a minimal field content necessary to form them. However, a realistic implementation of their structure could give new insights. For example, the property to have the scale of formation of strings as the only characteristic energy can be wrong. Moreover, such a study would permit to obtain the energy per unit length of the strings as a function of the GUT parameters. We will present such a realistic study in a given SO(10) model, assuming standard hybrid inflation. For this purpose, we will first explain how the cosmological and particle physics aspects of the model permit to reduce the string dynamics to only a few fields. Then, giving an ansatz for these realistic structures, we will present the numerical solutions of the model, and discuss the microscopic and macroscopic properties of these cosmic strings as a function of the GUT parameters.