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Reproductive Organs, gametes and Fertilisation
Testes and Ovaries
What you should know
• The structure and function of reproductive organs and gametes and their role in fertilisation.
• Gamete production in the testes. The roles of seminiferous tubules, interstitial cells, testosterone, prostate gland and seminal vesicles.
• Gamete production in the ovaries to include maturation of ova and the development of a follicle. Site of fertilisation in the oviduct and zygote formation.
Reproductive Organs and Gametes
Prior Knowledge
•Reproductive organs produce gametes•Male gamete- sperm•Female gamete- egg/ova•Male reproductive organ- testes•Female reproductive organ-ovary
Production of Gametes
•A germ line is the sex cells (eggs and sperm) that are used by sexually reproducing organisms to pass on genes from generation to generation.
•Gametes are produced by germline cells
MALE REPRODUCTIVE SYSTEM
PUBIC BONE
BLADDER
URETER
RECTUM
PENIS
ERECTILE TISSUE
URETHRA
TESTIS SCROTUM
EPIDIDYMIS
VAS DEFERENS/ sperm duct
SEMINAL VESICLE
PROSTATE GLAND
The testes are the site of sperm (spermatozoa) production
The testes are also the site of manufacture of the male sex hormone testosterone
Sperm are formed from germline cells in tiny tubes called Seminiferous Tubules
Seminiferous tubules unite to form coiled tubes that connect to the Sperm Duct – free swimming sperm leave the testes in the sperm duct
TESTES
SEMINIFEROUS TUBULE
INTERSTITIAL CELLS
Interstitial Cells
Between the seminiferous tubules are cells called the Interstitial CellsThese cells produce the hormone TestosteroneTestosterone passes directly into the blood stream Fertilisation depends on the motility of the sperm - motility requires a fluid medium and a source of energy
TESTES• Seminiferous tubules – produce sperm• Interstitial cells– secrete testosterone
Interstitial cells
Seminal Vesicles and Prostate
The seminal vesicles and the prostate gland are known as accessory glands
•Semen consists of 10% sperm and 90% fluid and as sperm pass down the ducts from testis to penis, (accessory) glands add various secretions
•The prostate gland and seminal vesicles secrete fluids that maintain the mobility and viability of the sperm. This fluid is called semen
Seminal Vesicles
Seminal Vesicles –secrete a liquid rich in fructose to provide energy for sperm motilitythe liquid contains hormone-like compounds that stimulate contraction of the female reproductive tractthese contractions help the sperm to reach the oviduct (where fertilisation takes place) quicker than ‘swimming’ alone
Prostate Gland
The prostate gland secretes lubricating liquid containing enzymes
These enzymes maintain the fluid at optimum viscosity for sperm motility
Just before ovulation the cells lining the female cervix secrete a watery mucus
this watery mucus is easily penetrated by sperm
FEMALE REPRODUCTIVE SYSTEM
VAGINACERVIX
UTERUS
ENDOMETRIUM
OVARY
OVIDUCT
Ovaries
Eggs or Ova are formed from germline cells in the female ovariesThe ovaries contain immature eggs at various stages of development
Ovulation is when a mature ovum is released, from the ovary, into the oviduct
Fertilisation takes place in the oviduct if sperm are present - fertilised egg or zygote develops into an embryo
GRAAFIAN FOLLICLE
Follicle
Each ovum (egg) is surrounded by a structure called a follicle which protects the ovum
The follicle secretes the female sex hormone called oestrogen
After ovulation it secretes the sex hormone progesterone, as well as oestrogen
Try these questions . . . .
1. Where in a testis are sperm produced?2. Which hormone is produced by interstitial
cells?3. Which accessory glands secrete a liquid rich in
hormone-like chemicals?4. Describe the contribution to fertilisation made
by these chemicals5. Name the structure that surrounds the egg in
an ovary
Answers . . . .
1. Seminiferous tubules2. Testosterone3. Seminal vesicles4. They stimulate the female reproductive tract
to contract, creating movements that help the sperm reach the oviduct
5. follicle
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