Fertilisation and zygote formation

In this talk, we turn our attention to fertilization and zygote formation, framing our discussion around the key stages of fertilization, beginning with the formation and preparation of male and female gametes and how their union initiates critical molecular events. We will explore the mechanisms that ensure monospermic fertilization, formation of the zygote, and the rapid cell divisions known as cleavage. The transition from zygote to blastocyst, its emergence from the zona pellucida, and the early steps of implantation will also be discussed. These foundational processes lay the groundwork for all subsequent stages of human development. Fertilization is a remarkable event in human biology where two specialized cells unite to create a new individual. The journey begins with gametogenesis, the formation of haploid male and female gametes, sperm from the testes and eggs from the ovaries. These gametes hold half the usual chromosomes, fundamental for restoring the diploid count after fertilization. Millions of sperm are deposited during intercourse, but only a few reach the egg. Chemical and physical cues guide the sperm to the use site, starting a complex molecular ballet. Fertilization is defined by both collaborative and competitive events. Sperm must undergo capacitation in the female tract, involving membrane changes that prime them for fusion. At the oocyte, sperm confront the corona radiata, then the glycoprotein rich zona pellucida. Enzymes from the acrosome