No abstract

The success of fertilisation in mammals is linked to the correct migration of spermatozoa in the different compartments of the female genital tract and the adequate timing of their interaction with the female gamete. In many mammalian species including human, the deposition of semen in the vagina is followed by the sperm migration through the cervix, the uterus and then the oviduct before reaching the site of fertilisation. This sperm transit within the female tract includes mechanical and biochemical interactions with the luminal fluids leading to selection of spermatozoa able to fertilize the oocyte.The first physiological barrier the spermatozoa will have to go through is the cervix whose vaginal side is covered by a highly viscous mucus, the cervical vaginal fluid (CVF) 1 . The CVF proteome was analyzed in humans in various physiological conditions (1, 2), mainly during pregnancy (3-7) or in several pathologies such as human papilloma virus (8) or candida albicans (9) infections. But few studies have investigated the CVF proteome during the cycle (10, 11). The amount of CVF increases at the time of ovulation concomitantly with a higher state of hydration and a reduced viscosity, to facilitate sperm migration (12). The mechanical properties of the mucus are essential to select spermatozoa with the highest fertilizing ability, i.e. with normal morphology and efficient mobility. The main structural components of the cervical mucus are mucins, highly glycosylated, high-molecular-weight proteins assembled into a filamentous and viscous mesh (13). The transcription of the mucin genes is increased at oestrus in the bovine cervical epithelium (14). The amount of mucins and their level of glycosylation are expected to contribute to the viscosity of the mucus (11). Therefore, the quantification of proteins such From the ‡INRA, UMR 85 Physiologie de la Reproduction et des Comportements,