Cervix - Anatomy & Physiology

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()Map REPRODUCTIVE SYSTEM (Map)
FEMALE REPRODUCTIVE TRACT



Introduction

Structure

  • The anatomy of the cervical canal is adapted to suit a particular pattern of reproduction
  • Thick-walled
  • Non-compliant (firm)
  • Mare and carnivores have a simple cervix bulging into the vagina to form a distinc recess (vaginal fornix).
  • Lumen is the cervical canal
  • Folds surround the lumen
    • Single fold and smooth surface in the queen and bitch
    • Multiple folds protruding into the cervical canal in the cow, ewe, sow and mare

Cow and Ewe

  • High volume of mucous production
  • Multiple folds
  • Cervical rings form interlocking finger-like projections known as interdigitating prominences.
  • Elaborate system of folds and crypts to provide a site of storage where sperm are protected from the spermicidal environment of the vagina and uterus in the ewe.
  • Allows semen to be ejaculated directly into the uterus for rapid transport to the oviducts in the cow.

Sow

  • Less mucous secretion
  • Multiple folds
  • Cervical folds form rings (cervical rings)
  • Ensures a tight coupling of the penis with the cervix to ensure that the large volume of semen produced by the boar is deposited in the uterus.

Mare

  • Low volume mucous secretion
  • Multiple folds
  • Many longitudinal folds of mucosa that protrude into the vagina (fornix vagina)
  • Soft during oestrus

Bitch

  • Single fold
  • Relatively smooth surface
  • A portion protrudes into the cranial vagina (fornix vagina).

Queen

  • Small
  • Thick walled compared to the uterus or vagina
  • Single fold
  • Smooth surface

Function

  • Provides a physical barrier to the uterus therefore preventing abortion due to infection by isolating the foetus from the external environment. It does this by creasing a highly viscous mucous plug. Closure is via the mucosal folds.
  • Barrier to sperm transport in the ewe, cow, bitch and queen, but not in the sow and mare.
  • Assists with the storage and survival of sperm by admitting sperm to the genital tract at a time when fertilisation is possible (around ovulation).
  • Mucus production for lubrication and to prevent microorganisms from entering the uterus.
  • Remodels itself at the end of gestation to allow birth and to stimulate the development of maternal behaviour.

Anatomical Boundaries

  • Located between the Uterus and the Vagina.

Histology

Histological Section of the Cervix of a Ewe- Courtesy of J.Bredl, Copyright RVC 2008
Histological Section of the Cervical Lumen of a Ewe- Courtesy of J.Bredl, Copyright RVC 2008


  • The lumen of the cervix is lined by a simple columnar epithelium containing many mucous producing cells. Some cilia may be seen on these cells.
  • Uterine cervix protrudes into the upper vagina and contains the endocervical canal that links the uterine cavity with the vagina.
  • The endocervical canal is lined by a single layer of tall columnar mucus-secreting cells.
  • Where the cervix is exposed to the vagina (the ectocervix), it is lined by thick stratified squamous epithelium.
    • Cells of the ectocervix often have clear cytoplasm due to their high glycogen content.
  • The junction between the vaginal and endocervical epithelium is abrupt, normally located at the external os. This is the point where the endocervical canal opens into the vagina.
  • The main bulk of the cervix is composed of tough, collagenous tissue with relatively little smooth muscle.
  • Under the squamocolumnar junction, the cervical stroma is infiltrated with leukocytes which defend against microorganisms.
  • It is the cervical stroma that is influence by the ovarian hormones.

Vascularisation

  • Uterine artery off the Internal Iliac artery (External Iliac artery in the Mare).

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