Cervix

CERVIX

  • Cervix is thick walled sphincter like structures
    • Separates vagina from the uterus
    • Connective tissue is the major component
    • Some smooth muscles also found
    • Lumen is narrow and exhibits annular rings
      • Very prominent in cow and ewe – form interlocking rings
      • Less prominent in the mare
      • In the sow the rings are cork screw shaped
    • Corresponding spiral twisting in the tip of penis of the boar
    • Epithelial lining
    • Columnar cells and goblet cells
    • Secrete mucus
    • Mucosa is intricately folded that increases secretory surface
    • Mucus is composed of glycoproteins
    • Mucus has unique biophysical properties
      • Ferning, elasticity, viscosity and stickiness
    • Physical and chemical properties of the mucus change during different phases of the estrous cycle
      • Ex: estrogens increase the intermolecular space to 2-5 µm
      • Progesterone reduces it

Functions of cervix

  • Transport of sperm
    • Ejaculation into vagina near the cervix in most species
    • Sperm oriented towards cervix
    • Hydrolytic enzymes in the semen digest back bone protein in the cervical mucus and remove cross linkages of mucin
    • Channels for sperm passage appear
  • Sperm reservoir
    • Large number of sperm lodged into cervical crypts
    • Released slowly later
    • Prevents inundation of uterus by sperm
    • Makes the sperm available at the site of fertilization for up to 24h after mating
  • Sperm selection center
    • Several sperm lodged in cervical crypts never get released
    • Particularly those that are less motile
    • Thus cervix selects only vigorously motile sperm for transport to the site of fertilization
  • Protection of upper reproductive tract
    • Cervical mucus becomes thick and viscous during the luteal phase and seals the URT
    • This seal persists till next estrus or parturition
  • Helps in parturition
    • Gross biochemical changes increase the size of the cervix enormously to allow the passage of the calf

Cervix during pregnancy

  • During pregnancy a tightly viscid, non ferning thick and turbid mucus occludes, the cervical canal, acting as a effective barrier against sperm transport and invasion of bacteria in the lumen, thus preventing the uterine infections.
  • The only other time cervix is open before parturition, at this time the cervical plug liquefies and the cervix dilates to permit the expulsion of the fetus and the fetal membranes.
Last modified: Saturday, 7 January 2012, 6:35 AM