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Cervix, Vagina and Vestibule

The cervix is a site with special clinical significance, since it is both susceptible to cancer and also relatively accessible for routine diagnostic examination.

The cervix is also prone to inflammation; see WebPath for an illustrative example.

The cervix includes the opening (os) from the uterus into the vagina.  The tissues associated with this opening are capable of extreme stretching during childbirth.  

In the vicinity of the os is a transition from the simple columnar, endometrial-type epithelium of the endocervix to the stratified squamous (nonkeratinized) epithelium of the ectocervix, which is continous with that of the vagina.  The endocervical mucosa contains many epithelial crevices which confer a glandular appearance.

Before puberty, the epithelial transition occurs near the os.  However, enlargement of the uterus and cervix during puberty cause the endocervical mucosa to evert, resulting in a transitional zone of columnar epithelium on the outer surface of the cervix, called the ectropion.  Squamous metaplasia eventually converts this zone into stratified squamous epithelium, but in the process some invaginations of columnar epithelium may lose their connection to the surface.  Continuing secretion at such sites results in the formation of small Nabothian cysts.

The epithelial changes which occur around the cervical os seem to predispose this site to malignant transformation.  For examples of cervical dysplasia, see WebPath and WebPath.

The cervical stroma is largely fibrous, with a high proportion of elastic fibers, interwoven with smooth muscle.  The stroma is also highly vascularized and richly innervated.

The vagina is lined by non-keratinized stratified squamous epithelium.  The epithelial cells accumulate glycogen as they approach the surface.  

With H&E stain, these glycogen-loaded cells appear "empty", with unstained cytoplasmic spaces.  With PAS stain the vaginal epithelium stains bright pink/violet.  

Supporting fibromuscular tissue is highly vascular and richly innervated, with no clear differentiation of mucosa and submucosa (unlike esophagus, which has a superficially similar epithelium).  Trichrome stain facilitates observation of smooth muscle.

The vulvar vestibule (between labia majora and labia minora) is lined by stratified squamous epithelium, non-keratized to thinly keratinized.  Opening into the vestibule are Bartholin's glands (lined by columnar mucus-secreting cells) and highly variable Skene's glands (analogous to the male prostate).



Comments and questions: dgking@siu.edu

SIUC / School of Medicine / Anatomy / David King

http://www.siumed.edu/~dking2/erg/cervix.htm
Last updated:  13 April 2010 / dgk