The male reproductive system

Male Reproductive Structures & their Function Table

The female reproductive system

Female Reproductive Structures & their Function Table

• A gamete is a?sex cell?(in animals: sperm and ovum; in plants pollen nucleus and ovum) produce by meiosis
• Gametes differ from normal cells as they contain?half the number of chromosomes?found in other body cells
• This is because they only contain one copy of each chromosome, rather than the two copies found in other body cells
• In human beings, a normal body cell contains 46 chromosomes but each gamete contains 23 chromosomes
• Gametes have?adaptations?to increase the chances of fertilisation and successful development of an embryo

Sperm Cell & Egg Cell Table

Comparing sperm and egg cells

Adaptive Features of Gametes Table

Comparison of Gametes Table

• During?ejaculation?in the?male, millions of sperm cells move along the?sperm duct?(also known as the?vas deferens)
• The sperm are suspended in?semen?(a fluid secreted by the?prostate gland)
• The semen passes into the?urethra
• During sexual intercourse,?semen is ejaculated into the vagina of the female, near the cervix
• The sperm cells then follow a chemical trail and travel through the plug of mucus in the cervix to reach the?uterus?(the womb)
• The sperm cells then travel into the?oviducts
• If a sperm cell meets an egg cell in the oviduct, fertilisation can occur
  • This is most likely to occur 1-2 days after the female has?ovulated?(released an egg cell from one of her ovaries into an oviduct)

   

• Fertilisation is the?fusion of the nuclei from a male gamete (sperm cell) and a female gamete (egg cell)
  • During fertilisation, the head of a sperm cell releases enzymes that digest a path through the protective outer layer of the egg cell, allowing the sperm to pass through the egg cell membrane
  • Once this occurs, the egg cell immediately releases a thick layer of material that prevents any more sperm cells from entering,?ensuring only one sperm cell can fertilise the egg cell

   

• When the male and female gametes fuse, they become a?zygote?(fertilised egg cell)
• This zygote contains the full?46 chromosomes?(23 pairs of chromosomes), half of which came from the father and half from the mother
• The zygote divides by?mitosis?to form two new cells, which then continue to divide like this until an?embryo?is formed after a few days
• Cell division continues and eventually many of the new cells produced become?specialised?to perform particular functions and form all the body tissues of the offspring

The process of fertilisation in humans

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