 The following organs make up the mare’s reproductive tract  2 Ovaries  2 Fallopian Tubes  Uterus  Cervix  Vagina  Vulva  Mammary glands are accessory organs

 Exterior opening to reproductive canal  Consists of:  Labia  Clitoris  Vestibule  Pneumovagina (windsucking)  Poor conformation  Vulva collects feces  Air and debris can be sucked into the reproductive tract  Can be inherited  Can be sealed with a caslick (episolasty)

 6 to 8 inch long muscular, mucous membrance – lined tube which connects the vestibule of the vulva to the cervix  Can change in color and vascularity due to hormonal changes during a mare’s estrous cycle

 Acts as a barrier between the vagina and uterus  During a point of estrus it will become flaccid allowing the passage of semen and breeding instruments

 Multilayer, hollow, Y-shaped organ with a uterine body and 2 branches (Horns)  Suspended in the body by 2 ligaments called broad ligaments  Myometrium  Muscular tissue  Provides contractions that expel foal during birth  Endometrium  Innermost layer  Containing a rich blood supply and many glands

 AKA Fallopian Tubes  Connects the tip of the uterine horn with an ovary  Infundibulum  Ovarian end of the oviduct  Enlarged and shaped like a catchers mitt with finger-like projections called fimbriae  Fertilization of the ovum occurs here  Isthmus  Final portion of the oviducts  Narrows and joins the uterus

 Both unique in shape and makeup  Kidney bean shaped  Ovulation Fossa  Concave side of the ovary  Follicles 35 millimeters or larger are considered capable of ovulating  Corpus Luteum  Forms after the follicle has ruptured  Secretes progesterone

 Estrous  Cycle  Estrus  Actual Heat  Anestrous  Not cycling  Winter Seasons

 Reproductive seasons  Spring & Summer  Series of estrous cycles  Estrous Cycle  days  Since it only happens in certain months they are considered seasonal polyestrus

 Estrus  Actual Heat  5-7 Days  Characterized by receptivity to stallion  Diestrus  days  Mare will reject stallion Bite or kick

 Endocrinology  Study of hormones  Hypothalamus  Controls ovaries, oviducts, and uterus  Located in the mid-brain  Environmental Cues  Start the reproductive season with a release of the hormone GnRH Gonadotrophic Releasing Hormone Released by the hypothalamus Stimulates the pituitary gland  Located at the base of the brain

 In response to GnRH, the pituitary releases to gonadotrophic hormones  Follicle Stimulating Hormone Stimulates follicle growth  Luteinizing Hormone Stimulates ovaries  When follicles reach approx mm in diameter  Secrete Estradiol Specific form of estrogen Peak immediately prior to ovulation

 High concentrations of estradiol stimulate the release of LH  Stimulating ovulation  Support the initial stages of the corpus luteum (CL) development  Ovulation occurs at the end of estrus  Follicles undergo rapid conversion to form a CL  Luteal cells with the CL secrete progesterone

 Progesterone  Inhibits the release of LH  Changes mare behavior to diestrus  If mare does not conceive, production is halted Accomplished through the action of prostaglandin F2 (PGF2) Released by the uterus days after ovulation Causes destruction of CL  Luteolysis