Uterus Anatomy Quiz

Female Reproductive System

• The female reproductive system consists of:
  • Ovaries (bilateral)
  • Oviducts (Fallopian/uterine tubes)
  • Uterus
  • Cervix
  • Vagina
  • External genitalia (vestibule, vulva)
  • Associated glands
  • Mammary gland (covered in integumentary system)

Ovaries

• Produce the female gametes (ova) through oogenesis
• Have an endocrine function, producing sex hormones (mainly estrogens and progesterone)
• Structure:
  • Cortex: broad peripheral zone containing follicles in various stages of development
  • Medulla: contains connective tissue, nerves, blood, and lymph vessels
• Species differences:
  • In the mare, the cortical tissue is focused around the ovulation fossa

Ovarian Follicles

• Contain an oocyte surrounded by specialized epithelial cells
• Structure varies depending on stage of development
• Types:
  • Primordial follicles: primary oocyte enclosed by flattened, simple squamous follicular cells
  • Primary follicles: primary oocyte enclosed by a simple cuboidal layer of follicular cells
  • Secondary follicles: oocyte enclosed by several layers of follicular cells
  • Tertiary follicles: follicle becomes larger, with small liquid-filled areas (antrum) between granulosa cells

Oviduct (Uterine Tube)

• Muscular tube from ovary to uterus
• Functions:
  • Receives the ovum and directs it into the oviduct lumen
  • Provides a favorable environment for fertilization
  • Transports the zygote to the uterus for implantation
• Structure:
  • Tunica muscularis: inner circular and outer longitudinal smooth muscle layers
  • Serosa: contains blood vessels and nerves
  • Mucosa: epithelium is columnar with motile cilia on most cells, and non-ciliated cells with secretory granules

Uterus

• Functions:
  • Provides a sterile and inert environment for development of the conceptus
  • Enables nutrient/oxygen/waste exchange via the placenta
• Structure:
  • Endometrium: mucosa divided into two zones (functional and basal)
  • Myometrium: smooth muscle layers (inner circular and outer longitudinal)
  • Perimetrium: serosa

Cervix

• Thick-walled, muscular structure
• Functions:
  • Provides a seal that prevents organisms and substances from entering the cranial vagina
  • Acts as a gatekeeper, holding the products of conception within the uterus until parturition
• Structure:
  • Endocervix: lined by simple columnar epithelium with mucus-secreting cells
  • Ectocervix: lined by stratified squamous epithelium

Vagina

• Fibro-muscular tube with three layers: mucosa, muscularis, and serosa/adventitia
• Mucosa:
  • Epithelium is stratified squamous with patches of simple columnar epithelium and mucus-producing cells
  • Rugae: numerous folds separated by channels of variable depth
• Cyclical changes in vaginal epithelium:
  • Height of epithelium and degree of keratinization vary with hormonal fluctuations during the estrous cycle

Ovaries

• Ovaries have two major functions: producing female gametes and sex hormones
• Ovarian structure consists of cortex (broad peripheral zone containing follicles) and medulla (connective tissue, nerves, blood, and lymph vessels)
• Species differences exist in ovarian structure, such as the mare having reversed cortical and medullary tissue

Ovary Cortex

• Lined by a low cuboidal epithelium (germinal/surface epithelium)
• Tunica albuginea: a layer of connective/fibrous tissue
• Contains numerous follicles with oocytes in different stages of development

Follicular Development

• Folliculogenesis occurs upon sexual maturity, with one or more primordial follicles maturing during each reproductive cycle
• Follicular growth and maturation depend on follicular stimulating hormone (FSH) from the adenohypophysis (pituitary gland)

Ovarian Follicles

• Contain an oocyte surrounded by specialized epithelial cells
• Size, content, and wrapping of the follicle vary depending on the stage of development

Follicle Stages

• Primordial follicles: primary oocyte enclosed by flattened, simple squamous follicular cells; retained in a resting stage since fetal ovary formation
• Primary follicles: primary oocyte enclosed by a simple cuboidal layer of follicular cells; start forming after puberty (FSH, LH)
• Secondary follicles: oocyte enclosed by several layers of follicular cells; oocyte completes meiosis; follicular cells proliferate through mitosis and are called granulosa cells
• Tertiary follicles: follicle becomes larger, with small liquid-filled areas appearing between granulosa cells (antrum); granulosa cells acquire receptors for FSH
• Mature (Graäfian) follicle: secondary oocyte detaches from the cumulus oophorus and floats free in the follicular fluid; ready to ovulate

Corpus Luteum (CL)

• Forms from the follicle after ovulation; blood into antrum forms corpus hemorrhagicum
• Granulosa and theca cells transform into luteal cells (hypertrophy and hyperplasia)
• CL is a temporary endocrine organ that secretes progesterone and estrogens in response to FSH and LH
• In some species, luteal cells contain a yellow pigment (lutein)

Corpus Albicans (CA)

• Involution of the corpus luteum results in a fibrous scar called corpus albicans

Follicular Atresia

• Majority of follicles do not ovulate and degenerate; oocyte, zona pellucida, and follicular cells degenerate and are resorbed

Oviduct (Uterine Tube)

• Muscular tube from ovary to uterus with 3 sections: infundibulum with fimbriae, ampulla, and isthmus
• Functions include transporting the oocyte and providing a site for fertilization

Female Reproductive System

• Consists of ovaries, oviducts, uterus, cervix, vagina, external genitalia, and associated glands
• Major functions include production of female gametes, endocrine function, reception of male gametes, provision of a suitable environment for fertilization and fetal development, and nutrition of the newborn through the mammary gland

Test your knowledge of the uterus anatomy, including the different layers and their functions. Learn about the muscles of the uterus and their role in childbirth.