Pineal Gland

What is the shape and location of pineal gland? #fdc500

Shape: Small, unpaired

Location:

• Epiphysis (above brainstem/diencephalon)

• Between cerebral hemispheres

What organs send signals to the pineal gland? #fdc500

Eyes

What hormones does the pineal gland produce? #fdc500

• Melatonin

• Serotonin

• Other peptide hormones

What are the 2 functions of melatonin? #fdc500

• Regulates body clock

  • Controls sleep-wake cycles in response to light and dark

• Gonadotrophic effects

  • Influences seasonal breeding that is affected by day length

  • Capability to increase or suppress the release of hypothalamic GnRh

Sheep #ff8a00

• What type of breeders are sheep

• What stimulates melatonin production in sheep

• How does melatonin affect sheep reproduction

• When in the breeding season for sheep

• Describe the melatonin levels in sheep during autumn/winter vs spring/summer

What type of breeders are sheep: Short day breeders

What stimulates melatonin production in sheep: Darkness

How does melatonin affect sheep reproduction: Melatonin increases GnRH release (promoting reproductive activity)

When in the breeding season for sheep: Autumn-winer (short days, long nights)

Describe the melatonin levels in sheep during autumn/winter vs spring/summer:

• Autumn-winter: ↑ Melatonin → ↑ Reproductive activity

• Spring-summer: ↓ Melatonin → ↓ Reproductive activity

Horses

• What type of breeders are horses

• How does melatonin affect horses

• When is fertility highest in horses

• What happens to melatonin levels in horses during spring-summer

What type of breeders are horses: Long day breeders

How does melatonin affect horses: Melatonin suppresses GnRH release causing reduced fertility during short days

When is fertility highest in horses: Spring-summer (long days, short nights)

What happens to melatonin levels in horses during spring-summer: Melatonin levels decrease allowing increased reproductive activity