1. A reference to a woman's uterus and peritoneum (the membrane that lines the abdominal cavity and covers most of the abdominal organs): When Jenny was at the gynaecologist's, she was told that the metroperitoneal area in her body was totally healthy and that she could have a child whenever she wanted to!
2. Etymology: from the Greek peri-, meaning "around" + tonos, "a stretching" = "a stretching around".