Female Reproductive System — Overview

Parts

• Ligaments

• Ovaries

• Oviducts

• Uterus

• Cervix

• Vagina

• Vulva

• The estrous cycle

Female Reproductive System — Functions

• More complex than the male reproductive system

• Functions:

  • Produces sex hormones

  • Develops gametes

  • Receives male gametes

  • Furnishes a site for gametes to fertilize the ovum

  • Provides environment for embryo to grow and develop

  • Carries embryo for entire pregnancy

  • Pushes offspring out when fully developed

Left and Right Broad Ligaments

• Broad sheets of peritoneum from the abdominal cavity

  • Mesovarium supports the ovary

    • Ovarian end = suspensory ligament of the ovary

  • Mesosalpinx supports the oviduct

  • Mesometrium supports the uterus

    • Tip of uterine horn caudally to inguinal ring = round ligament of the uterus

The Ovaries

• The female gonads — female equivalent of the male testes

• Shape varies among species

• 2 main functions:

  • Produce gametes in follicles = oogenesis

  • Produce hormones: estrogens, progestins, relaxin

The Ovarian Cycle

• Uniparous species — ovaries produce one mature ovum per cycle (horses, cattle, humans)

• Multiparous species — ovaries produce multiple ova per cycle (cats, dogs, sows give birth to a litter)

• Ova are not constantly produced in ovaries

• Cyclical sequence of events under influence of FSH and LH

Follicle Development Stages

1. Primary Follicle — immature oocyte surrounded by a single layer of flattened follicular cells; follicular activation

2. Growing Follicle — oocyte starts to grow in size; glycoprotein zona pellucida layer forms; granulosa cells multiply; antrum is formed

3. Mature Follicle — oocyte sits in mound of cumulus oophorus; zona pellucida surrounded by corona radiata; estrogen at peak level

4. Ovulation — mature follicle ruptures; gamete released into oviduct, now called an ovum; empty follicle fills with blood to form corpus hemorrhagicum

5. Corpus Luteum — formed from cells lining corpus hemorrhagicum; produces the progestins needed to maintain pregnancy if ovum is fertilized

Ovulation

• Occurs spontaneously in most species (result of rising levels of LH)

• Induced ovulators — ovulation occurs after breeding (cats, camels, rabbits, ferrets)

Follicular Atresia

• Not all follicles activated in a single ovarian cycle will fully develop and ovulate

• Follicles may degenerate at any stage of development

• Normal part of each ovarian cycle

Oviducts = Fallopian Tubes = Uterine Tubes

• Guide ova from ovary to uterus

• Serve as the usual site for fertilization of ova by spermatozoa

• Extend from tips of uterine horns

• Fimbriae "catch" ova in the infundibulum

The Uterus

• Hollow muscular organ, usually Y-shaped

• Forms part of placenta and afterbirth

• 3 layers: endometrium, myometrium, perimetrium

The Cervix

• Smooth muscle sphincter between the body of the uterus and the vagina

• Normally tightly closed, except:

  • During estrus

  • During parturition

The Vagina and the Vulva

• Vagina

  • Muscular tube that receives penis during breeding time

  • Acts as birth canal at parturition

• Vulva

  • Vestibule — urethra opens on floor of vestibule

  • Clitoris — homologous to the penis of the male

  • Labia