EGGS AND SPERM

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EGGS AND SPERM
Eggs (ova) and sperm have half the number of chromosomes of normal body cells. They are called haploid cells rather than diploid cells. A single egg cell is called an ovum. Collectively, eggs and sperm are called gametes or sex cells. When fertilization occurs, an egg (ovum) and a sperm fuse to form a zygote.

EGGS AND SPERM HAVE SEVERAL IMPORTANT ADAPTATIONS LINKED TO THEIR STRUCTURE.
EGGS
An egg cell (ovum) is one of the largest cells in the human body and can just be seen without using a microscope.
-          Has a haploid nucleus - containing only half the number of chromosomes of a normal cell nucleus
-          Has a large cytoplasm- which contains the nutrients for the developing embryo.
-          Many mitochondria- needed for mitosis (cell division) after fertilization.
-          Has a special cell membrane- which only allows one sperm to fertilize it.






SPERM
Has a haploid nucleus- containing only half the number of chromosomes of a normal cell nucleus
Has a tail (for motility)- which propels it through the cervix, uterus and oviducts towards the egg.
Has many mitochondria (where respiration occurs)- to release the energy needed for its journey towards the egg.
Have special enzymes in a structure called called acrosome, which break through the cell membrane of the egg during fertilization.



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