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  1. 1. Reproduction Anastasia Kellogg
  2. 2. The Reproductive System of the Mare <ul><li>The mare’s reproductive organs are supported by the broad ligament </li></ul><ul><li>The main organs of the female reproductive system are the ovaries, oviducts, and uterus </li></ul><ul><li>The ovaries are the gonads of the female animal, and there are two of them in each animal </li></ul><ul><li>The two main functions of the ovary are the production of eggs (ova) and hormones </li></ul>
  3. 3. The Reproductive System of the Mare <ul><li>Each ovary is kidney shaped, with a length two inches and a width of an inch and a half </li></ul><ul><li>Developing ovum are surrounded by follicles </li></ul><ul><li>When the follicle bursts, ovulation occurs </li></ul><ul><li>Ovulation refers to the release of the egg by the ovary </li></ul><ul><li>Oviducts carry the egg from the ovary to the uterus, and are the sight of fertilization if it is to occur </li></ul>
  4. 4. The Reproductive System of the Mare <ul><li>The oviduct is 8-12 inches long </li></ul><ul><li>The oviduct may also be called the fallopian tube </li></ul><ul><li>The uterus, or womb, is where the unborn fetus grows </li></ul><ul><li>The uterus may be divided into the uterine body, the right horn, and the left horn </li></ul><ul><li>The three layers of the uterine wall are the serous membrane, the myometrium, and the endometrium </li></ul>
  5. 5. The Reproductive System of the Mare <ul><li>The uterus and birth canal join at the cervix </li></ul><ul><li>An ovum=an egg, the plural is ova </li></ul><ul><li>Fertilization refers to the union of the egg and sperm </li></ul><ul><li>The period between fertilization and parturition is called gestation </li></ul><ul><li>In the mare gestation lasts about 340 days </li></ul><ul><li>Gestation lasts longer in the jenny (female donkey) </li></ul>
  6. 6. The Reproductive System of the Mare <ul><li>Immediately after fertilization, the offspring is known as a zygote </li></ul><ul><li>After 6-8 days, the zygote implants itself on the uterine wall, in either the right or left horn, and it is an embryo; after the first trimester it is called a fetus </li></ul><ul><li>Parturition=birth </li></ul><ul><li>The placenta is the structure which surrounds the unborn fetus, through which nutrients and oxygen are passed from the dam (mother) </li></ul>
  7. 7. The Reproductive System of the Mare <ul><li>The three layers of the placenta are the allantois, amnion, and chorion </li></ul><ul><li>After birth the mare nourishes her foal with milk </li></ul><ul><li>The mammary glands of the mare are found in the udder </li></ul><ul><li>Lactation means the production of milk </li></ul><ul><li>Colostrum is the antibody rich first milk of the mare, which provides passive immunity to the foal </li></ul>
  8. 8. The Reproductive System of the Mare <ul><li>Mastitis is a swelling of the udder </li></ul>
  9. 11. The Reproductive System of the Stallion <ul><li>The testicles, or testes are the gonads of the male animal, and are the primary organs of the stallion’s reproductive tract </li></ul><ul><li>The testes produce hormones and sperm cells </li></ul><ul><li>Sperm cells, or spermatozoa, are the male sex cells </li></ul><ul><li>In the male fetus, the testes are located on the upper abdominal wall </li></ul>
  10. 12. The Reproductive System of the Stallion <ul><li>Soon after birth, the testes drop down through the inguinal ring and into the scrotum </li></ul><ul><li>If only one teste drops into the scrotum, and the other is permanently retained, the horse is referred to as a cryptorchid </li></ul><ul><li>The normal adult stallion has two testes located in the scrotum </li></ul>
  11. 13. The Reproductive System of the Stallion <ul><li>The testes are suspended from the abdomen by the spermatic cord, which also contains nerves and blood vessels </li></ul><ul><li>The blood vessels in the spermatic cord are arranged so that the blood is cooled before it reaches the testes, since heat inhibits sperm production </li></ul><ul><li>The muscles in the spermatic cord and scrotum control testicular temperature by positioning the testes close to the body in cold weather and farther away when they are warm </li></ul>
  12. 14. The Reproductive System of the Stallion <ul><li>The muscles within the spermatic cord are called the cremaster muscles </li></ul><ul><li>The muscles within the scrotum are called the tunica dartos muscles </li></ul><ul><li>The tissue which separates the two testes is the septum scroti </li></ul><ul><li>Each teste is surrounded by a fibrous capsule called the tunica albuginea </li></ul>
  13. 15. The Reproductive System of the Stallion <ul><li>Each teste is divided into several lobules called lobuli testis </li></ul><ul><li>Within each lobuli testis are the seminiferous tubules, which contain the primary germ cells, which are eventually to become viable spermatozoa </li></ul>
  14. 16. The Reproductive System of the Stallion <ul><li>Sperm production (spermatogenesis): </li></ul><ul><ul><li>The change from germ cell to spermatid (immature sperm cell) lasts about 60 days </li></ul></ul><ul><ul><li>Begins in the seminiferous tubules, where germ cells reproduce by meiosis, or sex cell division </li></ul></ul><ul><ul><li>An immature spermatid migrates from the seminferous tubules to the epididymis </li></ul></ul><ul><ul><li>As the spermatid migrates it gains maturity, losing cytoplasm and gaining a tail, or flagellum </li></ul></ul><ul><ul><li>Final maturation occurs within the epididymis </li></ul></ul>
  15. 17. The Reproductive System of the Stallion <ul><li>The epididymis is a long, U-shaped structure attached to the top (long axis) of each teste </li></ul><ul><li>While in the epididymis, sperm are nourished by the fluid around them, and chemicals prevent them from moving their flagellum while they mature, thus enforcing energy conservation </li></ul><ul><li>The vas deferens, or ductus deferens, is the duct which carries mature sperm from the epididymus to the urethra </li></ul>
  16. 18. The Reproductive System of the Stallion <ul><li>The accessory sex glands secrete seminal fluid into the vas deferens, forming semen </li></ul><ul><li>The accessory sex glands of the stallion are the seminal vesticles, the ampulla, and the prostrate gland </li></ul><ul><li>The seminal vesticles, or vesicular glands, secrete a large portion of acidic seminal fluid, which contains high levels of protein and potassium </li></ul>
  17. 19. The Reproductive System of the Stallion <ul><li>The ampulla is the the enlarged glandular portion of the vas deferens, and secretes a large amount of fluid very similar to that of the seminal vesticles </li></ul><ul><li>The prostrate gland produces alkaline fluid that contains proteins, compounds that break up proteins, citric acid, and zinc </li></ul><ul><li>The bulbourethral glands produce a clear fluid that flushes the urethra of urine and bacteria before ejaculation </li></ul>
  18. 20. The Reproductive System of the Stallion <ul><li>Semen, carrying sperm, exits the body through the urethra </li></ul><ul><li>Ejaculation is the forcing of semen from the body </li></ul><ul><li>The urethra is found within the penis </li></ul><ul><li>The male copulatory organ is the penis, which rests in the sheath, or prepuce </li></ul><ul><li>The path of a sperm cell: </li></ul><ul><ul><li>From the seminiferous tubules (within the testes) </li></ul></ul><ul><ul><li>To the epididymis </li></ul></ul><ul><ul><li>To the vas deferens </li></ul></ul><ul><ul><li>To the urethra and out of the body </li></ul></ul>
  19. 21. The Reproductive System of the Stallion <ul><li>Geldings are not capable of reproduction </li></ul>