Cervicovaginal fluid (CVF)
The CVF is a mixture of oviductal, uterine and cervical fluid that has protective functions, through the innate immunity provided by mucins, also serving as a mechanical barrier and facilitating the transport of sperm into the cavity. uterine . This fluid is easily accessible in a non-invasive way and changes in its characteristics are currently used to detect, with great accuracy, the fertility window in natural methods for its regulation .
After ovulation and especially immediately after fertilization, the oviductal, uterine and CVF fluid increase several times their production and flow downstream . From the moment of fertilization, a rich molecular dialogue begins between the mother and the embryo that takes place in the oviduct. This molecular dialogue is extremely synchronized and has the purpose of favoring the development of the embryo in its various stages, in addition to facilitating transport to the implantation site in the uterus .
Later and during the implantation process, this molecular exchange is transferred to the endometrium, in the uterus, beginning around the 6th day after fertilization. In other words, part or all of the molecules secreted by the embryo and its mother from the moment of conception, come into contact with this "downstream river" formed, first by oviductal fluid and then by uterine fluid. The CVF will act as if it were an "estuary", capturing part of this dialogue between mother and child that takes place in the oviduct and in the uterus. Although the sampling methods are varied, the CVF collection in a medical silicone cup that the woman can very easily insert into the vaginal canal up to the cervix ensures a sample with little or no contamination.
Our preliminary tests, with the installation of a silicone cup for 1 h, showed a variation of two times in the magnitude of the protein content during 10 consecutive days of collection, reaching a peak in the first four days after ovulation.
In conclusion, the CVF appears to be the ideal candidate to non-invasively track, capture and investigate biomarkers of embryonic development in vivo.