Amyloid P component in normal human placentae.

The presence of tissue amyloid P component was determined by using a direct immunofluorescence technique on frozen sections of normal human placentae and umbilical cords from gestations of various durations. Amyloid P component was first detected at the 16th week of gestation and appeared to increase progressively in amount so as to be present in abundance in the term placenta. Placental amyloid P component was present in the perifetal capillary zone where basement membrane-like material and reticulin fibres are also found. Amyloid P component may be related to the maturation of the placenta.