Fertilization in tunicates: Loss of the paternal mitochondrion prior to sperm entry


  • Contribution no. 372 of the Bermuda Biological Station.


The spermatozoa of Ascidia nigra contain only one mitochondrion. Phase contrast and electron microscopical evidence is presented showing that the spermatozoon loses its mitochondrion before it enters the perivitelline space. Thus, in these organisms, the paternal mitochondrion plays no role in the development of the zygote and cannot contribute mitochondrial DNA to the genetic repertory of the zygote.