Trophoblast cells in first trimester decidual veins: a mechanism of normal placentation?

OBJECTIVE: In normal pieguaun, svncvtioirophoblasts (SCTB) are found in uterine venous blood and circulate to tin1 lungs. The- function ot these SCTB is unknown, hm presumably they gain access to the- matei ual circulation through decidual veins. This smd\ was undertaken to evaluate the presence of'S(]TB in first trimester decidnal veins. STUDY DESIGN: Decidua from 17 elective abortions (H-li> week) wenstained with antibodies to cuokeratin, u- smooth muscle antigen, Factoi \ 111 and human placental laetogen (ÜAKO immunologie reagents), and examined using liglit microscop\. RESULTS: All 17 cases showed SCTB in decidual veins. Venous SCTB were present in decidua a distance 1 cm awa\ from the placental bed. No evidence of direct imasion ol SCTB into decidual stroma was seen. In 17/17, SCTB in veins were entrapped in ( oagulum. In 4 ' 1 7 of specimens', placental viiu weie also seen in the veins, distant from the placental bed and from the shell ol extravillous SCTB. CONCLUSION: SCTB was present in decidual veins but did not imade into sunounding siioma. We speculate that SCTB entrapped in venous cloi max have a paracrine etfect enhancing locali/ed tiophobbstic modification of endomc-irium. Furthermoie. Placental giouih may occur by villous extension inio decidual veins.