Proacrosin appears in the Golgi complex as early as the mid-pachytene stage and immediately thereafter initiates partition to be equally distributed in spermatids. The anti-proacrosin monoclonal antibody 4D4 (mAb 4D4) was used as a marker of these cytoplasmic events in ten men exhibiting spermatogenesis arrest in three specific stages: (i) leptotene/zygotene spermatocyte I with impaired chromosome pairing (six cases), (ii) early pachytene I (one case) and (iii) metaphase/anaphase I (three cases). Prophase arrest stages were identified on testis sections stained by silver nitrate. MAb 4D4 labelling revealed two types of leptotene/zygotene arrest depending on whether proacrosin was expressed or not. The data obtained enabled us to distinguish between: (i) nuclear blockages due to chromosome and/or nuclear matrix anomalies, when cytoplasmic events were either inhibited or not inhibited, and (ii) nuclear anomalies due to microtubular disturbances. In this latter case, cytokinesis was impaired as early as the prophase I, thus indicating a relationship between the Golgi partitioning and the microtubule network. Data show that meiotic arrest investigations, by means of an appropriate marker of the cytoplasmic events, provide valuable information on spermatogenic developmental processes.