Small mammalian eggs have a small amount of nutrients. Fertilization in mammals is internal. Ripen egg cells enter the paired oviducts, where they are fertilized. Millions of sperm cells after ejaculation enter the uterus using flagella. The first sperm that reaches the egg penetrates inside its membrane. After this, a protective membrane begins to form around the ovum, making it inaccessible to other sperm. The sperm nucleus fuses with the nucleus of the egg.
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.