28 s and 18 s ribonucleic acid from mammalian spermatozoa.

The majority of RNA is spermatozoa from the epididymis and ductus deferens of mice was found to be 28 s and 18 s RNA. This RNA was also seen in human ejaculated spermatozoa. Our evidence indicates that little or none of the 28 s and 18 s RNA is transcribed in the maturing mouse spermatozoa and that the majority is synthesized in the primary spermatocyte. This RNA may be necessary to maintain post-meiotic translation during spermatogenesis.