To become pregnant , the following steps must occur:. Following ejaculation, the semen forms a gel that protects it from the acidic environment of the vagina. The gel is liquefied within 20 to 30 minutes by enzymes from the prostate gland. This liquefaction is important for freeing the sperm so transportation may occur. The seminal plasma is left in the vagina. The protected sperm with the greatest motility travel through the layers of cervical mucus that guard the entrance to the uterus. During ovulation, this barrier becomes thinner and changes its acidity, creating a friendlier environment for the sperm.
Egg meets sperm
Where Does Fertilization Occur? 10 Facts That May Surprise You
Fertilized eggs travel down the pig's oviduct. Ciliary action and contractions help to move the egg to the uterus where it becomes implanted. Triplets occur when three mature eggs are released near the same time, fertilized, and implanted in the uterus. Less likely, but possible, is when a fertilized egg splits in two and then one part splits in two again.
Early embryo mortality in natural human reproduction: What the data say
Purpose : To explore the possible relationship between sperm quality and embryo development, pregnancy and implantation rates, in patients undergoing intracytoplasmic sperm injection ICSI. Methods : Fertilization and cleavage rates, quality of embryos, blastocyst development, pregnancy and implantation rates were analyzed in embryos from couples undergoing first ICSI treatment cycle. The couples were allocated in five groups, according to semen parameters: Group 1: patients with normal semen parameters, Group 2: patients with mild oligo-astheno-teratozoospermia, Group 3: patients with severe oligo-astheno-teratozoospermia, Group 4: patients with obstructive azoospermia, Group 5: patients with non-obstructive azoospermia. Results : Fertilization and cleavage rates, quality of embryos as well as blastocyst development rates were significantly reduced, as semen quality decreased. However, no significant differences were observed in clinical pregnancy and implantation rates.
Data associated with the article are available under the terms of the Creative Commons Zero "No rights reserved" data waiver CC0 1. FResearch : Dataset 1. Figure 2 data,