 We are going to look at two very crucial and highly specialized cells, egg and sperm cells. These lead to each and every one of us being here, hence they are so very crucial. The female sex cells are known as the ova or egg cells or ovum for one. The male sex cells are known as sperm cells. Both of these sex cells are known as gametes. Gametes are an organism's reproductive cells. They have half the genetic information that all of our other body cells have and so are known as haploid. Humans have 23 chromosomes and most of the cells in our body have two of each. So 23 pairs of chromosomes makes 46 in total, one for my mother and one for my father. However, gametes, so the sperm or egg cells, only have one of each and which one, whether it is from the mother or the father, is random. This means that each of our gametes can be different from each other, depending on the mix of chromosomes. Although the egg cell and sperm cell have this very important similarity of only 23 chromosomes, they are very different cells to look at. First off, they are hugely different in size. A human egg cell is spherical in shape and around 130 micrometers in diameter, that's 0.13 millimeters. Not very large but what size do you think a sperm cell is? Have a look at this egg cell being fertilized and you can see the difference in size. As you can see, there is a lot of sperm and ejaculation varies but contains at least 20 million sperm per milliliter, that's a lot. In comparison, on average, a woman releases just one egg per month. The reason there are so many sperm is to increase the chances of fertilization. When one sperm reaches their egg cell and their nuclei fuse, this gives two of each of the 23 chromosomes. And so makes up the 23 pairs and 46 chromosomes in total. The egg cell is large because it goes on to become a new person and so is packed full of cell organelles which allow it to create new energy and parts. The sperm on the other hand only passes on its nucleus. Let's take a look at what is special about sperm. The head is full of the cell parts that produce energy and also the nucleus. The sperm needs lots of energy to get moving. As you can see, there is a tail that it uses to swim to the egg cell. The sperm has a long journey while the egg cell doesn't move. You can also see the cap right at the top of the sperm. That's called the acrosome and contains special enzymes. These enzymes are used to break through the protein coating that is around each egg cell. Because this protein varies from species to species, this egg prevents cells from being fertilized by sperm from another species. From this video, you should now know the difference between an egg and a sperm cell. The egg is much bigger, does not move and contains organelles needed for the fertilized egg to develop into an embryo and onto a new human. Sperm cells are much smaller and more tall and there are millions of them. They only pass on their nucleus and so are able to be small. And most importantly, you should now know that gametes, so the egg and sperm cells only contain 23 chromosomes each. This is known as haploid. When the egg is fertilized by a sperm cell, the 23 chromosomes from each pair up giving the normal diploid amounts of 23 pairs of 46 chromosomes.