An X-shaped crossing formed by the crossing over of homologous chromosomes during meiosis when genetic material is exchanged.
                                                            
                                                     
                        
                                                
                        
                        
                            Cross-overs between chromosomes in meiosis.
                                                            
                                                     
                        
                                                
                        
                        
                            Observable regions in which non-sister chromatids of homologous chromosomes cross-over each other.