Fluid gives foetuses a taste of outside
A new study suggests a mother’s uterine fluid can give a growing foetus information on the outside world.
A developing foetus bathes in a mixture of cellular secretions and proteins unique to its mother’s uterus. Before fertilisation, the pH of uterine fluid helps create a conducive environment for sperm migration, and afterward, its volume supports the embryo as it implants onto the wall of the uterus.
But new evidence suggests that uterine fluid may play another key role in embryonic development; communicating the mother’s outside conditions to the foetus, so it can prepare accordingly.
Researchers have been testing the hypothesis that blood flow via the placenta could allow the body to communicate the mother’s condition to the foetus. A team at the Chinese Academy of Sciences has now found that the foetus can react to changes stemming from the mother’s diet long before the establishment of the placenta.
“This suggests the involvement of uterine fluid as the communication medium to transfer information between the maternal environment and the floating embryo,” says senior author En-Kui Duan, a reproductive biologist at the Institute of Zoology, Chinese Academy of Sciences.
“The preimplantation period is a critical time for programming offspring health, and thus, expecting mothers should keep a good diet and good mood, and stay away from harmful chemicals during this critical window.”
While the field of inquiry is still new, experts suggest that information in extracellular vesicles (molecular packages that move from cell to cell) within uterine fluid and tissue deliver their cargo, including microRNAs and amino acids, to the foetus.
These molecules may be tagging foetal cell DNA in ways that alter which genes are being expressed, and thus can contribute to ‘programming’ how the embryo and/or placenta develop.
The next step for researchers will be to learn which specific maternal environmental exposures and/or behaviours could change the composition of molecules transported via the uterine fluid to the foetus.
Hongmei Wang, co-senior author of the new paper published in Cell Press, speculates that uterine fluid could someday be used to analyse or even manipulate what signals are being received by a foetus.
“For now, uterine fluid collection is not a standard biomarker, yet many studies have revealed its potential role for non-invasive analysis, and we also see great potential in it,” she says.
“One, it can be screened by using ultrasound recording coupled with computational/biomechanical analysis; and two, uterine fluid can also be collected during an endometrial examination.”