Epididymis

Each epididymis is formed by a single convoluted tubule seen in multiple cross sections. It is lined by a tall pseudostratified columnar epithelium. These cells bear stereocilia on their luminal surface that absorb fluid released from the testes along with sperm. In this section, the spermatozoa can be seen in the lumen throughout the epididymis. What crucial change do spermatozoa undergo in the epididymis?