The egg is motionless, usually large in size and contains nutrient reserves. It provides the embryo of the future organism with the bulk of the cytoplasm and, especially in egg-laying animals, with nutrient material (yolk). The egg is hundreds of times, and in animals with yolk-rich eggs, it is millions of times larger than the sperm. The egg of most animals is surrounded by protective membranes.
Sperm cells are very small and motile. In mammals, the sperm consists of a head (its length is about 5-10 microns), a neck and a tail (their total length is about 60 microns). In the head is a nucleus containing a haploid set of chromosomes. The cytoplasm in the head is very small. In the neck there are a small number of mitochondria that generate energy for sperm movement, and centriole, which provides oscillations of the flagellum lying along the axis of the tail.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.