Sperm

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Swimming sperm

Sperm are the male reproductive cells. Most animals and plants use sperm to reproduce. They have different ways of making and releasing the sperm. In all cases the sperm meets with the egg of the female and grow into a new organism.

The name sperm is taken from the Greek word sperma meaning seed.[1]

Anatomy[change | change source]

An animal sperm cell is capable of movement, as it has to get to the uterus to meet with the ovum. Animal sperm cells (including humans) have small 'head' and a long tail called a flagellum. The flagellum acts like a motor to propel the sperm cell through the female reproductive system.

A plant sperm cell is non motive, it can not move by itself. Plant sperm cells are contained within the pollen of a plant. They reach other plants through the wind, or insects such as bees.

In humans[change | change source]

A sperm cell attempting to enter and merge with an egg.

Human sperm is made in the testicles of a man. Human sperm contains 23 chromosomes. A human needs 46 chromosomes, so a sperm cell is called a haploid as it only has half. The other half is contained within the ovum or egg of a female. During sex, semen is shot out of the man's penis during ejaculation. Semen carries the sperm into the womans vagina and down to the ovum in the uterus. During ejaculation millions of sperm cells are released, but only one hundred or so reach the egg.[2] The egg can merge with one sperm cell that reaches it. Because it now has 46 chromosomes, it is called a diploid, like ordinary cells of the body. This diploid is called a zygote, and it can grow into a fetus and eventually a baby.

In plants[change | change source]

Plant sperm cells cannot move by themselves. Plant sperm cells are contained within a sticky liquid called pollen, Thus, they rely on transportation to take their sperm cells to other plants. For example a bee lands on a plant to collect the pollen. Some pollen will get stuck to the bee. The bee moves on to another plant and the pollen falls onto that plant. The pollen falls down a pollen tube until it reaches the ovule at the bottom.

References[change | change source]