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Anatomy & Physiology Anatomy & Physiology

of Pelvic Organsof Pelvic Organs

Median Section Of Female PelvisMedian Section Of Female Pelvis

External Female Genitalia External Female Genitalia - vulva - vulva

Female Reproductive TractFemale Reproductive Tract- Anterior View- Anterior View

UTERUSUTERUS• Located centrally

within pelvic cavity• Hollow muscular organ• 7.5cm long• Consists of:

– Upper body– Lower neck (Cervix)

• Walls separated by slit like space (uterine cavity)

Body

CervixUterineCavity

Uterine cavityUterine cavity

• Lined by endometrial epithelium

• Undergoes cyclical changes in thickness

• Upper third of epithelium will shed during menstruation

CERVIXCERVIX• Neck of the womb• Has an internal and external os• Can be divided into 2 parts

– Endocervix– Ectocervix– These are lined by different types of cells

Endocervix

Ectocervix

EndocervixEndocervix

Tall columnar surface epithelium arranged into folds (crypts)

EctocervixEctocervix

•

Ectocervix: Covered by a multi-layered Squamous EpitheliumEctocervix: Covered by a multi-layered Squamous Epithelium

Squamo-columnar junctionSquamo-columnar junction

Endocervical cells - delicate

Squamous cells - protective

Squamo-columnar junction

EndocervixEndocervix EctocervixEctocervix

Squamo-columnar JunctionSquamo-columnar Junction

Squamo-columnar junctionSquamo-columnar junction

VAGINAVAGINA

• Covered by protective stratified squamous epithelium (epithelium is continuous with ectocervix)

The Menstrual CycleThe Menstrual Cycle• 28 days

• 4 phases:– Menstruation– Proliferative phase– Ovulation– Secretory phase

• Oestrogen & progesterone levels fluctuate

The menstrual cycleThe menstrual cycle

Squamous EpitheliumSquamous Epithelium

Fully mature if high levels of Oestrogen

Clinical dataClinical data

• Different cells may be seen depending on hormone levels (oestrogen & progesterone).

CervixCervix• Changes to the position of the

cervical epithelia occur especially at puberty and during pregnancy

• The uterus increases in size and this pushes down on the cervix

• Ectropion can occur at these times

• The endocervical cells are pushed out to lie on the ectocervix

EctropionEctropion

Normal Ectropion

Ectropion/’Erosion’Ectropion/’Erosion’

MetaplasiaMetaplasia• The endocervical cells are

transformed into squamous cells through the process of squamous metaplasia, a protective mechanism.

Squamous MetaplasiaSquamous Metaplasia

•Delicate endocervical epithelium is replaced by squamous epithelium through a process called metaplasia.

•The area where metaplasia takes place is called the transformation zone

Squamous MetaplasiaSquamous Metaplasia

New squamo-columnarjunction

Old squamo-columnar junction

Endocervical crypts remain beneath the ‘new’ squamous epithelium

Nabothian follicles can sometimes develop

Transformation ZoneTransformation Zone• The area where metaplasia occurs is

called the TRANSFORMATION ZONE• This is an unstable area where

Cervical Abnormalities can arises• The whole of the TZ must be

sampled when a cervical smear is taken

MetaplasiaMetaplasia

Squamous epithelium

Crypt openings in transformation zone

Squamo-columnar junction

Everted columnarepithelium (‘ectropion’)

Transformation zone

Transformation Zone CellsTransformation Zone Cells• Endocervical cells• Metaplastic cells

• Can be identified on cytology sample• Indicates good quality• Should be present in most samples

from women aged 25-50

Post-menopausal cervixPost-menopausal cervix

TransformationZone

SCJ

Transformation zone may not be visible in a post-menopausal cervix. Tip of broom may reach it in some cases.