“…The origin of these cells has not been completely clarified although detailed studies of amniotic fluid cell cytology have been made and several classifications of amniotic fluid cells have been suggested primarily on the basis of morphology [1][2][3][4][5][6]. Investigations into the origin and differentiation of amniotic fluid cells using cultured amniotic fluid cells and antibodies against several tissue-specific antigens [7][8][9][10] have demonstrated that the majority of amniotic fluid cells are derived from the exfoliating fetal surfaces such as the skin, mucosa (oral, nasal, vaginal), respiratory tract, and umbilical cord [1]. A large proportion of the cells in amniotic fluids from normal fetuses and fetuses affected with genodermatoses was found to be Manuscript received February 19, 1994; revised June 21, 1994; accepted for publication June 27, 1994. Part of this work was presented at the 2nd Tricontinental Meeting of the JSID, SID, and ESDR, Kyoto, October 28-31, 1993 comprised of periderm cells and epidermal keratinocytes although a small number of nonkeratinocytic cells such as macrophages were included in amniotic fluid cells [11 -16].…”