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प्रश्न
How is polyspermy prevented in humans?
उत्तर
When a sperm comes in contact with the zona pellucida layer of the ovum, it induces changes in the membrane of the ovum to block the entry of additional sperms. This, thus, prevents the polyspermy and ensures that only one sperm can fertilise an ovum.
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संबंधित प्रश्न
Briefly explain the events of fertilisation and implantation in an adult human female.
Name the hormones secreted and write their functions by corpus luteum and placenta (any two).
Explain the process of implantation.
Fertilizins are emitted by ______.
Match the following and choose the correct options:
| A. | Trophoblast | i. | Embedding of blastocyst in the endome |
| B. | Cleavage | ii. | Group of cells that would differentiate as embryo |
| C. | Inner cell mass | iii. | Outer layer of blastocyst attached to the endometrium |
| D. | Implantation | iv. | Mitonic division of zygote |
Test-tube baby means a baby born when ______.
The solid mass of 8-16 cells formed from zygote after successive mitotic divisions is called ______.
Read the following and answer from given below:
Cleavage is the series of rapid mitotic divisions in the zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. An embryo with 64 blastomeres is known as a blastocyst and has a blastocoel cavity. Blastocyst gets implanted in the uterine wall and leads to pregnancy.
The Site of implantation is ______
What is the significance of ampullary–isthmic junction in the female reproductive tract?
Where does the first cleavage division of zygote take place?
