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Fertilization

Fertiliazation is recognized as the process of which a female and male combine to produce an offspring. This process can also be referred to as conception.

But Fertilization should be known as the fusion of gametes to create a new organism.

As seen in some species, fertilization does not always require a male and female as seen in plants, bacteria, and other organism in separate and somewhat complicated manners.

In Humans and other mammals and animals it occurs when the ovum (or egg) from a female and sperm from a male becomes combined.

When conception occurs than an embryo is formed.

Depending on the organism fertilization can be internal or external.

The cycle of fertilization and development of new individuals is called “Sexual Reproduction“.

Humans

–  Fertilization can occur at any point from the Ovaries to the Vagina.
–  It can also occur outside the reproductive tract such as the abdomen or other locations
–  The typical location is within the Fallopian Tube.

The Sperm

–  Movement of the sperm (swimming) occurs by a flagella or “a tail”
–  The sperm must find the egg to initiate fertilization
–  Once the sperm attaches to the egg it must pass through outer cell layers of the egg.
–  The sperm releases an enzyme that allows it to continue through the layers of cells

The Egg

–  Has several layers of cells

1.)  Corona radiata
2.)  Zona pellucida

–  Once sperm has entered through this layer a “cortical reaction” occurs.
–  This reaction release enzymes from the egg that cause changes to occur through out the entire egg.
–  It no longer allows other sperm to pass through the cell layers
–  This allows or ensures that multiple sperm do not fertilize the same egg
–  Fertilization of the sperm and egg occur after the cortical reaction and the two gametes fuse together and conception occurs.
–  The egg is a specific and important aspect of Female Reproduction

Mitosis and Meiosis occur

–  Meiosis is essential for “sharing” or “transferring” of genetic material
–  Typically 1/2 of genetic genes come from sperm and 1/2 come from the egg
–  The egg is much larger than the sperm – due to the sperm only holds genetic material and the egg provides nutrition and other necessary requirements of the embryo.
–  Therefore, due to the donation of chromosomes – each offspring will be genetically different from their parents but holding some similarities.