What is fertilization and where does it occur?

Fertilization is the fusion of male and female gametes to form a zygote. It occurs in the ampulla of the uterine tube within 24 hours of ovulation.

What are the main outcomes or results of fertilization?

The major outcomes include restoration of the diploid chromosome number (46), determination of genetic sex (XX for female, XY for male), and initiation of embryonic development and cleavage.

What are the steps involved in the fertilization process?

The key steps are penetration of corona radiata and zona pellucida via acrosomal enzymes, fusion of sperm and oocyte membranes, completion of meiosis II in the oocyte and formation of pronuclei, and fusion of pronuclei to form a zygote with 46 chromosomes.

What is capacitation and why is it important for fertilization?

Capacitation is a 7-hour conditioning process in the female genital tract that removes glycoprotein coats from the sperm's acrosome. This makes the sperm capable of fertilization by enabling the subsequent acrosome reaction.

How does in vitro fertilization (IVF) work?

IVF involves stimulating ovarian follicles and aspirating oocytes, artificially capacitating sperms and culturing them with oocytes in vitro, and transferring 8-cell stage embryos into the uterus, with freezing of remaining embryos.

What are the barriers that sperm must penetrate to fertilize the oocyte?

Sperm must penetrate three barriers: corona radiata, zona pellucida (composed of glycoproteins ZP1, ZP2, ZP3), and vitelline membrane. This is aided by enzymes like hyaluronidase and acrosin released during the acrosome reaction.

What factors help sperm reach the oocyte in the uterine tube?

Sperm transport is aided by prostaglandins in semen and oxytocin from the neurohypophysis, which stimulate uterine contractions, and ciliary action and smooth muscle contractions that help move the oocyte.

Fertilization – Fusion of Sperm & Ovum

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