Question

Explain the events that take place once a sperm reaches the oviduct till it becomes a foetus.

Answer 1

Fertilisation occurs when a sperm enters the fallopian tube and encounters a mature egg (oocyte). The process of fertilisation and foetal development can be summarised as follows:

1. Fertilisation: Sperm penetrates the egg, resulting in the creation of a zygote. The merging of genetic material restores diploid chromosomes and creates a new person.
2. Zygote Formation: The zygote undergoes rapid cell division through mitosis, forming a solid ball of cells called a morula.
3. Blastocyst Formation: The morula transforms into a blastocyst, a fluid-filled structure with a central cell mass. The blastocyst moves via the fallopian tube and into the uterus.
4. Implantation: The blastocyst connects to the endometrial lining of the uterus and implants. In this procedure, the blastocyst invades the uterine lining.
5. Formation of Germ Layers: After implantation, the blastocyst develops into three germ layers (ectoderm, mesoderm, and endoderm) that produce numerous tissues and organs.
6. Formation of embryo: The blastocyst develops into an embryo, and organogenesis begins. During this stage, the body's organs and structures begin to develop.
7. Development of Foetus: The developing organism is called a fetus after the eighth week. During the fetal stage, organs and tissues develop and mature more.