1. Process of gamete formation is known as gametogenesis
2. Gametogenesis that involved sperm formation is known as spermatogenesis, whereas those involved ovum formation is known as oogenesis

Necessity of gametogenesis:

• Produces gametes and haploid chromosomal number through meiosis
• Produces genetic variation in gametes
• Maintains diploid chromosomal number of zygote
• Produces genetic variation in offspring

• During foetus development, primordial germ cells divide mitocially to form spermatogonia

1. Each spermatogonia (2n) grows and develops into primary spermatocytes (2n)
2. Each primary spermatocyte (2n) divides by meiosis I to form tqo secondary spermatocytes (n)
3. Each secondary spermatocyte (n) divides by meiosis II to form two spermatids (n)
4. Each spermatid (n) undergoes differentiation to form sperm (n)

• The sperms formed move to epididymis to be matured
• Head of sperm contains nucleus and acrosome. The nucleus contains chromosomes and the acrosome contains enzymes for fertilisation.
• Midpiece of sperm contains abundant of mitochondria to produce more energy for movement
• The tail helps sperm to move

• During foetus development, primordial germ cells divide mitotically to form oogonia
• Polar body formed has size much smaller than secondary oocyte or ovum
• The three polar bodies will degenerate and do not take part in fertilisation
• At first, primary oocyte that surrounded by follicle cells is known as primary follicle
• At puberty, follicle stimulating hormone (FSH) secreted by pituitary gland stimulates the development of follicle in ovary
• Follicle cells start to divide by mitosis during development of follicle. The primary follicle developed into secondary follicle and then into a mature follicle,graafian follicle
• During the follicle development, primary oocyte undergoes meiosis I to form secondary oocyte.

1. At foetal stage, the primordial germ cells divide repeatedly by mitosis to form many diploid oogonium (2n)
2. Each oogonium grows ad develops to form primary oocyte (2n). Each primary oocyte is surrounded by a layer of follicle cells to form a primary follicle.
3. Before birth, the primary oocytes undergoes an incomplete meiosis I until prophase I
4. At puberty, one primary oocyte completes meiosis I to form a secondary oocyte (n) and a polar body (n). The haploid polar body formed also undergoes meiosis II to form another two haploid polar bodies
5. Secondary oocyte is surrounded by follicle cells known as secondary follicle 
6. Secondary follicle grows and matures to form graafian follicle which then moves to the surface of the ovarian wall
7. Ovulation: The Grafiian follicle bursts and releases the secondary oocyte into Fallopian tube
8. If fertilisation occurs, secondary oocyte completes meiosis II to form a polar body (n) and an ovum (n). All 3 polar bodies will degenerate.

Simillarities between spermatogenesis and oogenesis:

• Occur in reproductive organs
• Produce haploid gametes
• Involved in fertilisation