Explorers from the University of Bath are challenging the claims of two high profile papers from 2018 which reported that in the mouse, RNA needs to be added to sperm for them to be absolutely resourceful. The Bath findings undermine a proposed mechanism of epigenetic inheritance by which offspring inherit traits acquired by their parents.
In double-blind experiments, researchers from the Department of Biology & Biochemistry have proven that healthy mice pups could be born from sperm which has not gained brief RNA chains as they migrate by the epididymis—a ductular organ in which sperm acquire forward motility after they emerge from the testis.
This contradicts the results of the 2018 papers, which reported that mouse eggs fertilized with sperm taken from the ‘caput’ region of the epididymis—where sperm first enter the epididymis on leaving the testis—would not develop into viable embryos.
Lead author Professor Tony Perry stated: “Once I noticed these two papers I just thought ‘this cannot be right’ and with some quite straightforward experiments we’ve shown that it in all probability is not.
We’ve known for years that sperm taken from mouse testis contribute to full-term embryonic growth following fertilization. The 2018 research proposed that sperm would unaccountably have lost this capability in the caput region of the epididymis but then reacquired it. Here we’ve shown that sperm taken from the caput area of the epididymis can, in fact, assist full-term growth.
The Bath team took sperm from two regions of the epididymis, the caput, and the cauda; the cauda area is where sperm are usually taken from mice for in vitro fertilization, so we know they should work. Eggs had been fertilized with the sperm and healthy pups had been born from both sperm types (caput and cauda) with no significant difference in the number of pups born, their health, weight or fertility.