simple spermatogenesis and oogenesis UEC

Explain spermatogenesis

• Primodial germ cell divides mitotically to form diploid spermatogonium

• Diploid spermatogonium expands to form primary spermatocyte

• Primary spermatocyte undergoes meiosis 1 to form 2 secondary spermatocyte

• Each secondary spermatocyte undergoes meiosis 2 to form 2 haploid spermatids

• Haploid spermatids undergoes differentiation to form sperm

Explain oogenesis in phase 1

• Primodial germ cell undergo mitosis to form oogonium

• Oogonium develops into primary oocyte and is encapsulated with more than 1 layer of follicle cells to form primary follicle

• Oocyte undergoes meiosis 1 but stops at prophase 1 during fetal development

• No. Of oocyte decreases during puberty

Explain oogenesis in Phase 2

• during puberty, primary oocyte will complete meiosis 1 to form secondary oocyte and first polar body

• Secondary oocyte will undergo meiosis 2, stopping at metaphase 2

• However, first polar body will complete meiosis 2, forming 2 secondary polar body

• More than 1 layer of follicle cell will encapsulate secondary oocyte to form secondary follicle

• Which then develops into Graafian follicle, which releases oestrogen

Explain genesis in Phase 3

• Graafian follicle approaches surface of ovary and releases secondary oocyte into the Fallopian tube (ovulation)

• When sperm penetrates secondary oocyte, meiosis 2 is completed to produce ovum and a polar body

• Fertilization is when sperm nucleus fuses with ovum nucleus to produce diploid zygote

• The rest of polar body will be disintegrated by ovary

• And remaining follicles become corpus luteum

• After ferlisation, corpus luteum continues to grow and secretes oestrogen and progesterone

What happens to corpus luteum if there’s no fertilization?

The corpus luteum along with the secondary oocyte will degenerate and die, which will be removed by menstruation