Twin birth--identical or fraternal twins?
D005321:Extraembryonic Membranes / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D010920:Placenta / Q000033:anatomy & histology*; D010922:Placenta Diseases / Q000175:diagnosis / Q000473:pathology; D011247:Pregnancy; D014427:Twins