Normal histology	Histopathology	Pathological basis of disease	Clinical findings	
•	The endocervixis lined by a single layer of tall columnar mucus-secreting cells.
•	The ectocervix is lined by thick stratified squamous, non-keratinizing epithelium.
•	The main bulk of the cervix is composed of tough, collagenous tissue containing little smooth muscle.
•	Beneath the squamo-columnar junction, the cervical stroma is often infiltrated with leukocytes.	Abnormal histology:
•	Marked dysplasia from basal to superficial layer.
•	Atypical cells in entire thickness of cervical epithelium.
•	There is no morphological differentiation between the deeper & superficial layers.
•	The lesion is confined within the epithelial layer as the basement membrane is still intact with no evidence of breach by dysplastic cells. 

Cellular characteristics:
•	Increased nuclear-cytoplasmic ratio.
•	Hyperchromatic nuclei
•	Nuclear pleomorphism
•	Increased abnormal mitoses
•	Loss of polarity	Classification of CIN:
•	CIN I: mild dysplasia
•	CIN II: moderate dysplasia
•	CIN III: carcinoma-in-situ	•	Precursor of invasive cancer.
•	Generally asymptomatic, shedding of abnormal cells from cervix is usually detected by routine PAP smear.