Tuesday, October 3, 2017

Basic modalities of Transitional Zone

Hey Awesomites

Squamocolumnar junction ( the transitional zone ) is a junction formed by merging of squamous epithelium of the vagina with the columnar epithelium of endocervix.

Squamous non keratinized epithelium lining the vaginal mucosa has three distinct layers -
- Basal layer of cuboidal cells
- Middle layer of prickle cells
- Superficial layer of cornified cells

Embryologically, the junction consists of columnar epithelium that spreads over the external os and only the basal and middle layer of squamous epithelium lining the vaginal mucosa.

After attaining puberty, hormonal effects of oestrogen and progesterone induce metaplastic changes in columnar epithelium. Therefore, the squamous epithelium comes in close vicinity to the external os.

During reproductive age, growth of uterus, hypertrophy of cervical cells and associated hormonal changes and in females exposed to DES in utero, the transitional zone extrudes well out of the external os.

Due to high cellular activity and sensitivity to certain irritants and mutagens, there is high risk of dysplastic changes in the squamocolumnar epithelium and eventually carcinoma cervix. So, scrapings for PAP smear are done without difficulty from this exposed area to screen the patients.

In menopausal women, the atrophy of cervix leads to in drawing of SCJ into the canal. Hence the junction is not easily accessible and this ill exposure is the reason for high rates of false negative findings in PAP smear in older women! Hormonal therapy in such patients improves the positivity of results.


That's all
Jaskunwar Singh

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