Ultrastructural in situ hybridization and autoradiographic detection of foreign DNA in zebrafish spermatozoa

Conditions have been established which permit specific hybridization of foreign DNA to complimentary DNA in ultra thin sections of zebrafish sperm prepared for electron microscopy (EM) after fixation in 2% paraformaldehyde, 2.5% glutaraldehyde and embedded in spurs resin. Zebrafish sperm incubated with foreign DNA were subjected to ultrastructural in situ hybridization and autoradiographic detection to determine if the sperm could retain and internalize the foreign DNA sequences. Specific and intense signals were detected from the sperm head indicating that the zebrafish sperm are capable of internalizing foreign DNA.