Fig. 7. Comparison of E18.5 wild-type (WT), Xaf1o and Xaf2o placentas. (a,b) Halved placentas from the same litter fixed in glutaraldehyde. (c-d) Histological sections from paraffin-embedded placentas. (e-h) Semithin sections: labyrinthine trabeculae consist of three layers of trophoblast cells (designated I, II and III counting from the maternal towards the fetal blood spaces) and of the endothelium lining fetal capillaries; the trabecular thickening in Xaf2o placenta affects mainly layers I and II. E, nuclei of endothelial cells; F, fetal (allantoic) capillary; L, labyrinthine zone; M, maternal blood sinuses; S, spongiotrophoblast; T, nuclei of trophoblast cells; TI, nuclei of trophoblast cells from layer one; I, II and III, first, second and third layer of labyrinthine trabeculae. The green brackets delimit the placental barrier. Modified Mallory’s trichrome (c,d), Toludine Blue (e,f) and periodic acid-schiff (g,h). (a) and (b) are displayed at the same magnification. Scale bar: 500 µm (c,d); 25 µm (e,f); 12 µm (g,h).