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