Reproductive System of the Horse
Stallion Reproductive System
Mare Reproductive System
Ovary
Oviducts
Cervix
Infundubulum
Vagina
Uterus
Vulva
- external opening of the reproductive tract
- labia on each side are 12-15cm vertical slit below the anus
- muscular tube around 15-20cm, line with mucus
- very elastic to accommodate the stallions penis and passage of the foal during parturition
- enterance to the uterus
- forms a boundry between the inside and outside world
- opens to facilitate the passage of the semen
- two organs shaped like beans
- produce eggs
- once egg matures the follicle ruptures and the egg discharged
- carries the egg to the location of fertalization
- funnel shaped membrane that surrounds the ovary
- narrows and becomes the oviduct
- capable of expansion as foetus grows and develops
- two ligaments known as broad ligaments suspend it
- job is to hold and nourish the foetus
Functions:
- produce eggs
- produce female reproductive hormones
- provide housing and nutrients for the growing embryo
- birth the fetus at the correct time of development
- produce milk
Urethra
Vas Deferens
Prostate Glands
Glands Penis
Scrotum
Semen
Epididymis
Sheath
Testes
Scrotum
Functions:
- to product and ejaculate sperm
- to produce male hormones e.g. testosterone
- to produce sperm
- to store and mature sperm
- to maintain temperature control of the sperm in the testes
- secrete fluid which contains nutrients
- protective substances
- create semen
- to transport sperm from the vas deferens outside of the body
- transport sperm from the epididymis to the glands and urethra
- swells inside the mare and holds the penis in place to ensure all sperm has been ejected into the vagina
- fluid which is combined with sperm and ejaculated from the stallion to fertallise egg cell in the female
- covers the penis when not erect
- protects nerves of the penis
- protects the testes and ensures the sperm stays a suitable temperature
Female Hormones
Luteinising Hormone (LH)
Follicle Stimulating Hormone (FSH)
Oestrogen
Progesterone
Prostaglandin F2 Alfa
- responsible for development of reproductive system
- regulates oestrus phase
- prepares womb lining for implantation of the embryo
- responsible for bringing the mare into oestrus and causing the signs that the mare is in heat
- regulating function of the ovaries - growth and development of egg cells
- causes ovulation of the egg cell
- stimulates the growth of egg cells in the ovaries
- maintains lining of the uterus
- responsible for maintaining pregnancy
- during birth, responsible for contraction of muscle in the uterus
- during pregancy it is responsible for blood supply to the feotus
- during oestrus, prostaglandin starts a new oestrus phase if the egg isnt fertilised
Extras
Mares Cycle
Key Features
Signs a mare's in heat
- increased moodieness
- receptive to stallions
- increase urination
- winking of vulva
- presenting herself to be covered
- anoestrus - in winter mares dont have a cycle
- Oestrus - 4-5 days
- Dioestrus - 16 days - fertile not ovulating
- 21 day cycle
- oestrus cycle takes 21 days
- ovulation of a follicle occurs
- luteal phase - 5 days after ovulation when progesterones secreted
- FSH action early in dioestrus may produce a mid-cycle follicle
- day 13 post ovulation, PGF2a is secreated, permitting the onset of oestrus behaviour
- FSH activity causes selection of a dominant follicle, increasing oestrogen helps it develop to reach ovulatory status 21 days after previous ovulation