Figure 5.

GABRP expression in human placenta samples over gestation. (A–D) Human blastocyst developmental age 16 days. (A) GABRP expression is most prominent in primitive syncytium highlighted in dashes. GABRP is also expressed by emerging STB from the secondary villus (SV). (B) CGA is strongly expressed in areas of primitive syncytium while KRT7 (B) is expressed at a low level in these areas. (E–H) Six weeks 6 days human placenta was immunostained for STB markers CGA (E, G) and CTB/EVT marker KRT7 (F, H) in floating (E, F) and anchoring (G, H) villi. G) Solid arrow = STB; arrowhead = CTB; line arrow = EVT. I–O are placental villi from the first trimester at gestational ages (I) 5 weeks 5 days, (J) 6 weeks 6 days, (K) 7 weeks 6 days, (L) 8 weeks 2 days, (M) 13 weeks, (N) 20 weeks 6 days, (O) Term. Signal detected within the mesenchymal villous core at term is erythrocyte autofluorescence. (P) Corrected total cell fluorescence (CTCF) quantification of positive CTB/STB regions. First trimester samples showed higher fluorescence intensity values than second trimester and term. Best fit line is y = x + x². R² = 0.83. Scale bars = 100 µm.