Reproductive Anatomy of Mares

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Reproductive Anatomy of Mares

• ABAS 4090 Breeding Management

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Mare reproduction topics

• Mare anatomy and physiology
• Endocrinology of the estrous cycle
• Manipulation of the estrous cycle
• Mare management
• Anatomy of pregnancy
• Management of pregnancy
• Factors affecting fertility

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The Hypothalamus

• Gonadotropin Releasing Hormone (GnRH or LHRH)
• Oxytocin Synthesis
• Dopamine

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Pituitary Gland
Anterior Pituitary

• Follicle Stimulating Hormone (FSH)
• Lutinizing Hormone (LH)
• Prolactin

Posterior Pituitary

• Oxytocin Release

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Ovarian Anatomy

• Suspended from broad ligament but separate from
  the uterus
• Bean shaped with ovulation fossa at the eye
  (ovulation site)
• Varies greatly in size according to degree of
  activity

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Ovaries
Follicle

• Estrogen
• Inhibin
• Activin

Corpus Luteum

• Progesterone

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Ovarian Anatomy

• Follicles--
• 1o Source of Estrogen
• Contains the oocyte
• Two cell types
• granulosa
• inhibit premature maturation of ova
• synthesize estrogen precursor
• theca
• convert precursor to estrogen

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Ovulation

• Corpus Hemorragicum
• Blood Clot
• Develops after about 50 of ovulations

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Ovarian Anatomy

• Corpus Luteum
• Progesterone source
• Comprised of differentiated thecal and granulosal
  cells
• Sensitive to regression by PGF2a by 7 days after
  ovulation

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Common Ovarian Problems

• Hemorrhagic Follicles
• develops when follicle fails to luteinize
• produces neither estrogen or progesterone
• interferes with ovarian activity
• no effective treatment
• usually regresses after about 45-50 days

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Common Ovarian Problems

• Persistent Corpus Luteum
• Occurs when CL fails to regress in an open mare
• Diagnosed with ultrasound by Day 14
• with palpation, around Day 35-45
• Regresses with PGF2a treatment

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Common Ovarian Problems

• Granulosa Cell Tumor
• Produces testosterone
• Interferes with normal ovarian activity of either
  ovary
• Normal cyclicity eventually resumes after removal
  of the affected ovary

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Oviduct Anatomy

• Infundibulum
• Collects ova from ovulation fossa
• Ampulla
• Passage of ova to fertilization site
• Isthmus
• Capacitation of sperm
• Passage of the EMBRYO to the uterus

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Uterine Anatomy

• Broad Ligament
• Suspends Uterus and Ovaries
• Blood, Lymph, Nerves
• Enlarges during Pregnancy

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Uterine Anatomy

• Mesometrium
• Physical Support
• Blood, Lymph,
• Nerves
• Perimetrium
• Physical Support
• Encases Uterus

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Uterine Anatomy

• Myometrium
• Outer Longitudinal
• Inner circular
• Clearance of fluid during estrus
• Mobility and fixation of embryo
• Expulsion of fetus

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Uterine Anatomy

• Endometrium
• Stroma
• vascular
• Glands
• histotrophe production
• Luminal Epithelium
• prostaglandins
• embryonic support

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Uterus/cervix
Synthesis of

• Prostaglandin F2a

Target organ for

• Estrogen
• Progesterone
• Oxytocin
• Prostaglandins

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Estrus Uterus/Cervix

• Uterus
• Increased Edema
• Increased Contractility
• Cervix
• Edematous (open)
• Increased Mucus Secretion

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Diestrus Uterus/Cervix

• Uterus
• Edema Subsides
• Lower Contractility
• Cervix
• non-edematous (closed)
• Lower Mucus Secretion

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Cross Section of the Uterus
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ESTRUS ENDOMETRIUM
DIESTRUS ENDOMETRIUM
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Vagina

• Region between the cervix and vulva
• Middle of the three seals
• Estrus- secretes slippery mucus
• Diestrus- secretes sticky mucus

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Vulva

• Conformation
• Worsens with age and repeated pregnancies
• May permit passage of air and feces
• Caslicks procedure
• Urethral position
• Urine pooling
• Urethral extension
• Clitoral fossa
• Horbors pathogens

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Gonadotropin Release

• Estrogen
• () LH
• (-) FSH

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Uterine Anatomy

• Endometrium
• Stroma
• vascular
• Glands
• histotrophe production
• Luminal Epithelium
• prostaglandin
• embryonic support

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