Definitions [3]
Define.
Fertilization
The formation of a zygote by the union of male and female gametes is known as fertilization.
Definition: Fertilization
The union of a male gamete with the egg cell to form a zygote is called fertilization.
Definition: Fertilization in Human
The fusion of the male gamete (sperm) and female gamete (ovum) to form a zygote is called fertilization.
or
The formation of a zygote by the union of a sperm and an ovum is called fertilization.
Key Points
Key Points: Fertilization in Human
- Fertilization in humans is the fusion of male and female gametes (sperm and ovum) and is an internal process occurring in the oviduct, leading to the formation of a diploid zygote.
- During copulation, millions of sperms are released into the vagina, but only one sperm reaches the ovum due to selection and protective barriers around the egg.
- Before fertilization, sperm undergo capacitation and move towards the ovum; interaction between sperm and egg involves recognition molecules like fertilizin (ovum) and antifertilizin (sperm).
- The sperm’s acrosome releases enzymes that help digest the egg coverings (corona radiata and zona pellucida), allowing sperm entry through the membrane.
- After entry, the sperm nucleus and the ovum nucleus fuse (syngamy), forming a zygote (2n); this process restores the diploid chromosome number (46 in humans).
- Fertilization triggers completion of meiosis II in the oocyte, formation of the second polar body, and formation of the female pronucleus and male pronucleus.
- In humans, sperm carry 22+X or 22+Y chromosomes, while ova carry 22+X only, determining the genetic sex of the offspring.
