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 BLADDER URETER PUBIC BONE SEMINAL VESICLE PROSTATE GLAND RECTUM URETHRA ERECTILE TISSUE VAS DEFERENS/ sperm duct PENIS EPIDIDYMIS SCROTUM TESTIS

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 Cells These cells produce the hormone Testosterone Testosterone 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 motility the liquid contains hormone-like compounds that stimulate contraction of the female reproductive tract these 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 OVIDUCT ENDOMETRIUM OVARY UTERUS CERVIX VAGINA

Ovaries Eggs or Ova are formed from germline cells in the female ovaries The 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

Human Ovulation

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 . . . . Where in a testis are sperm produced? Which hormone is produced by interstitial cells? Which accessory glands secrete a liquid rich in hormone-like chemicals? Describe the contribution to fertilisation made by these chemicals Name the structure that surrounds the egg in an ovary

Answers . . . . Seminiferous tubules Testosterone Seminal vesicles They stimulate the female reproductive tract to contract, creating movements that help the sperm reach the oviduct follicle