Based on the process of fertilization and early embryonic development, here's the sequence of events arranged in order:
- Ovulation - The release of the ovum from the ovary.
- Acrosomal enzymes disrupt the corona radiata - The spermatozoon releases enzymes that help it penetrate the outer layer of the ovum.
- Oocyte activation - The binding of the sperm triggers changes in the ovum that prepare it for fertilization.
- Meiosis finishes - The secondary oocyte completes meiosis II, resulting in the formation of the female pronucleus.
- Female pronucleus forms - The genetic material from the ovum organizes to form the female pronucleus.
- Male pronucleus forms - The sperm’s genetic material also organizes to form the male pronucleus.
- Amphimixis - The fusion of the male and female pronuclei occurs, leading to the formation of a diploid zygote.
- Cytokinesis - The division of the cytoplasm occurs, leading to the formation of two separate cells.
- Spindle formation - The mitotic spindle begins to develop within the zygote for subsequent cell divisions.
This sequence provides a comprehensive view of the key events that occur during fertilization and the start of development.