Union of human egg and sperm

Equal transmission of alternative alleles through meiosis in heterozygotes ensures a balanced parental genetic contribution to offspring at each generation. Rinxas Verinxt. Mutations to the piRNA pathway component aubergine enhance meiotic drive of segregation distorter in Drosophila melanogaster. Wiley Interdiscip. Fertilization age is sometimes used postnatally after birth as well to estimate various risk factors. Furthermore, the surface of the endometrium produces a kind of rounded cells, which cover the whole area toward the uterine cavity. However, several genes that are located far from the centromere show substantial TRD and overall there is little evidence that TRD declines as a strong function of recombination distance from the centromere Figure 4.

Various exceptions to this sequence are possible, including artificial insemination , in vitro fertilization , external ejaculation without copulation, or copulation shortly after ovulation. The egg then plants itself on the uterin wall. Human physiology of sexual reproduction. The average time to birth has been estimated to be days 38 weeks and two days from ovulation , with a standard deviation of 10 days or coefficient of variation of 3.