Ultrastructural organization of the sperm nuclear matrix

The organization of DNA-protamine complexes and their association with the nuclear matrix have been analyzed in sperm nuclei by in situ Nick Translation at the electron microscope. The data obtained indicate that the chromatin organization in sperm nuclei is maintained during the sperm condensation by means of interaction with the nuclear matrix at fixed sites. The fine structure of the sperm nucleus and sperm nuclear matrix, investigated by sectioning and replica of freeze-fractured specimens, suggests that the lamellar array observed by freeze-fracturing in the sperm nuclei, could depend on the inner matrix which presents a regular organization of globular structures involved in the maintenance of chromatin domains.