Hidden obstruction: A rare case of hematometrocolpos in a young adolescent with vaginal atresia.

Hematometrocolpos is a condition characterized by the accumulation of menstrual blood in the uterus and vagina due to an obstruction, often caused by congenital malformations such as vaginal atresia or imperforate hymen. A 12-year-old girl presented with acute pelvic pain and absence of menarche. Ultrasound ruled out ovarian pathology but revealed distension of the cervix and vagina.

Mutation studies in ascidians: a review.

Historically, mutations have had a significant impact on the study of developmental processes and phenotypic evolution. Lesions in DNA are created by artificial methods or detected by natural genetic variation. Random mutations are then ascribed to genetic change by direct sequencing or positional cloning.