Fertilisation Process Overview

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Questions and Answers

What is the primary role of the trophoblast during implantation?

To invade the endometrium and facilitate implantation (correct)

To develop into the embryo

To support the formation of the placenta exclusively

To provide nutrients to the embryo

Which event occurs first after fertilization in the process of embryonic development?

The development of the morula

The formation of the zygote (correct)

The implantation of the blastocyst

The cleavage of the zygote

Which layer must sperm penetrate to fertilize the egg?

Zygote

Blastocyst

Morula

Cumulus oophorus (correct)

What is the significance of the cortical reaction during fertilization?

It prevents polyspermy by modifying the egg's outer layer Signup and view all the answers

What transformation occurs when the blastocyst reaches the uterus?

It adheres to the uterine lining and initiates implantation Signup and view all the answers

What is the primary outcome of the fusion of the sperm and egg nuclei?

Formation of a diploid zygote Signup and view all the answers

What is the term for the rapid series of mitotic divisions following fertilization?

Cleavage Signup and view all the answers

At what stage does the zygote first divide into two equal-sized cells?

Two-Cell Stage Signup and view all the answers

What characterizes the radial cleavage pattern?

Cells are arranged in a symmetrical manner Signup and view all the answers

What is the immediate structure formed after the morula stage during cleavage?

Blastula Signup and view all the answers

What happens during the formation of the blastocyst?

Fluid accumulates, creating a hollow cavity Signup and view all the answers

What defines the inner cell mass in a blastocyst?

It will ultimately develop into the embryo Signup and view all the answers

How many chromosomes does a diploid zygote contain?

23 chromosomes from each parent Signup and view all the answers

What is the primary purpose of capacitation in sperm cells?

To allow sperm to fertilize the egg Signup and view all the answers

Which structure is primarily responsible for the acrosome reaction in sperm cells?

Acrosome Signup and view all the answers

How does the cortical reaction contribute to the fertilization process?

It modifies the zona pellucida to prevent polyspermy. Signup and view all the answers

What must sperm achieve to reach the egg's plasma membrane?

Binding to egg receptors Signup and view all the answers

Which of the following layers must sperm penetrate first during fertilization?

Cumulus oophorus Signup and view all the answers

What initiates the formation of the zygote?

Fusion of sperm and egg nuclei Signup and view all the answers

Which event directly prevents other sperm from fertilizing the egg after one sperm has entered?

Cortical reaction Signup and view all the answers

What is the first step that occurs after sperm binds to the egg?

Membrane fusion occurs Signup and view all the answers

Study Notes

Fertilisation

Fertilisation is the fusion of a sperm cell from a male and an ovum (egg) from a female, creating a zygote.
This process is fundamental for sexual reproduction, initiating embryonic development.

The Process of Fertilisation

A. Sperm Transport

Sperm are deposited in the female reproductive tract after ejaculation.
They travel through the cervix, uterus, and into the fallopian tubes (where fertilization usually occurs).
Capacitation is a process sperm undergo, enabling them to fertilize the egg. This involves changes in the sperm's plasma membrane.

B. Interaction with the Egg

The egg is surrounded by layers: corona radiata (granulosa cells) and zona pellucida (a glycoprotein layer).
Sperm must penetrate these layers to reach the egg's plasma membrane.
Acrosome Reaction: Enzymes in the acrosome (a cap-like structure on the sperm's head) digest the zona pellucida, enabling sperm access to the egg.
Sperm Binding: Sperm bind to specific receptors on the egg's surface, after penetrating the zona pellucida.

C. Fusion of Sperm and Egg

Membrane Fusion: Sperm and egg plasma membranes fuse. This allows the sperm's nucleus to enter the egg.
Cortical Reaction: The egg releases enzymes that modify the zona pellucida, preventing further sperm entry and ensuring only one sperm fertilizes the egg.

D. Formation of the Zygote

The sperm nucleus and egg nucleus fuse, creating a diploid zygote with a complete set of chromosomes (23 from each parent).
The zygote starts its journey down the fallopian tube to the uterus.

Cleavage: Rapid Cell Divisions Post-Fertilisation

A. Overview of Cleavage

Cleavage is a series of rapid mitotic divisions that the zygote undergoes, creating a multicellular structure called a blastula.
These divisions result in smaller cells, called blastomeres.

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Description

This quiz explores the intricate process of fertilisation, highlighting the journey of sperm from the male reproductive system to the fertilization of the egg. Learn about key components such as sperm transport, capacitation, and the critical interaction between sperm and the egg layers. Test your knowledge on these fundamental concepts of sexual reproduction.