In eukaryotic cells, DNA is wrapped around histone proteins to form chromatin. Dynamic modification of histones by various chemical structures enables fine regulation of gene expression. Alterations in these complex regulatory mechanisms are at the root of many diseases. Histone lysine acetylation is known to induce gene expression. Other structures can be added to histones, whose effects on transcription remain largely to be elucidated. Most of them, like lactylation discovered in 2019, depend on cellular metabolism. We have begun to study lactylation in the context of murine spermatogenesis. This process of cellular differentiation is a model of choice for studying the regulation of transcription, due to the dramatic changes in chromatin composition and the gene expression program. We have generated novel epigenetic profiles consisting of the genome-wide distribution of acetylated and lactylated marks on three histone H3 lysines. The aim of this thesis is to contribute to the deciphering of the “histone code”, firstly by studying the role of lactylations on the transcriptional program. Secondly, the prediction of chromatin states will be refined by integrating our new data with existing epigenomic data at the two studied cellular stages, within neural network models.