Name: Lactation
Uploaded: 2019-07-19
Duration: 6 min 34 s
Description: When a baby is born, it cannot eat food like us to survive. It depends on lactation, a process through which it receives nutrition from its mother. Learn more.

Question

Explain the process of fertilization and implantation of the fertilized ovum.

Accepted Answer

Fertilisation

The process of fertilisation of an ovum happens by the following steps:

Sperm Capacitation: The physiological changes that the sperm undergoes to gain the capacity to penetrate.

Sperm-Zona Pellucida Binding: This allows the sperm to adhere to the ovum. It is a critical step in fertilisation.

Acrosome Reaction: The hydrolytic enzymes of acrosome help in dissolving the outer membranes of the egg. The sperm head penetrates the zona pellucida.

Egg Activation and the Cortical Reaction: The cortical reaction is a process initiated during fertilisation by the release of cortical granules from the egg, which prevents polyspermy.

Zygote:

Fertilisation is the union of a sperm and an egg. It forms a diploid cell called a zygote. Fertilisation generally occurs in a Fallopian tube.

Cleavage:

The zygote divides by mitosis several times to form a ball of cells called a morula.

Cleavage increases the number of cells. More cell divisions occur, and soon a fluid-filled cavity forms inside the ball of cells. At this stage, the ball of cells is called a blastocyst.

Blastocyst:

The process of blastocyst formation is an organising process that partitions the embryo into developmental regions.

The cells of the blastocyst form an inner and an outer cell layer. The inner layer of cells is called the embryoblast. This layer of cells will soon develop into an embryo.

Implantation:

The blastocyst continues the trip down the Fallopian tube and reaches the uterus about four or five days after fertilisation.

When the outer cells of the blastocyst, contact the cells lining the uterus, the blastocyst embeds in the lining. The process of embedding is called implantation. Once implantation occurs, the blastocyst is called an embryo.

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