The ectocervix is the part of uterus which plunges into apex vagina. A stratified squamous epithelium covers it. endocervical canal, establishes communication between vagina and endometrial cavity, paved with a mucous secreting glandular epithelium. Because acidity vagina, these two epithelia undergo metaplasia. Some oncogenic factors do ignite instead dysplasia. CIN1, CIN2, CIN3 correspond to ...