TRISOMY-21 PLACENTAS - HISTOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL FINDINGS USING PROLIFERATING CELL NUCLEAR ANTIGEN

Objective: The cause of growth retardation in trisomy 21 and other aut osomal trisomies is not known, but may be the result of defective cell proliferation, slowing of the cell cycle, or placental structural abn ormalities. Abnormalities of the fetal cell cycle may be reflected in placental growth and can be detected using proliferating cell nuclear antigen (PCNA). Methods: Twelve second-trimester and six third-trimest er trisomy 21 placentas were examined histopathologically and stained immunohistochemically using antibodies to PCNA. Normal age-matched pla centas were used as controls. Results: The second-trimester trisomy 21 placentas all exhibited many large irregular hypovascular villi. The third-trimester trisomy 21 placentas showed two patterns: (i) many lar ge, irregular hypovascular villi, and (ii) relatively normal-appearing villi with only a few abnormal villi and focal hypervascularity, PCNA staining was significantly greater in second-trimester placentas when compared to third-trimester placentas for both trisomy 21 and control s. There was no significant difference in PCNA staining in trisomy 21 placentas when compared to the normal age-matched controls, Conclusion s: PCNA staining indicates no significant differences in proliferation between normal and trisomy 21 placentas, Trisomy 21 placentas show vi llus abnormalities, including hypovascularity.