Topic 47 Sex cells – male sex cells.
Gametogenesis – conversion of germ cells into male and female gametes
- 2 types of gametogenesis – spermatogenesis, oogenesis
- Meiosis – cell division that takes place in the germ cells to produce male and female gametes
- Cytodifferentiation – development of specialised structures and functions in embryonic cells
- Gamete – sex cell that fuses with another during fertilisation in organisms that reproduces sexually
- 2 types of gametes – sperm, ovum
- The diploid somatic cells of an individual have one copy of chromosome set from the sperm and one copy from the ovum
- Sperm and ovum are haploid cells
- Gametes are produced in reproductive system called gonads
- Gonads produce sex hormones needed for the growth and development of the primary and secondary reproductive organs and structures
Sperm
- Cannot divide and have limited life span
- Develops in testicles (gonads)
- Ova only contain the X chromosome, whereas sperm contain X or Y. Thus, sperm cells determine the sex of an individual
- Structure:
- Head – contains nucleus with densely coated chromatin fibres surrounded by acrosome, which contains enzymes
- Mid-piece – has central filamentous core with many mitochondria around it for ATP production for movement
- Tail – is flagellum and is used for propelling movement
- Sperm are produced in the process of spermatogenesis in testicles
- Sperm are released from the male body in semen. Semen is produced in seminal vesicles, prostate gland and urethral glands
- Acrosome contains enzymes hyaluronidase and acrosin, which are needed to break the zona pellucida of ovum allowing the sperm to join with the secondary oocyte
- Shedding of acrosome, also called acrosome reaction, is the process in which acrosome fuses with zona pellucida, releasing its enzymes. It occurs in ampulla of fallopian tube