Fig. 2. Allantoic dysmorphogenesis and absence of endothelialization in T^C/T^C allantoises. (A-F) Hematoxylin and eosinstained sections of allantoises (al) in +/+ (A-C) and T^C/T^C (D-F) conceptuses. Mesothelial cells (arrowheads) were observed in +/+ and T^C/T^C allantoises. The dense core of +/+ allantoises (black outline, A-C) was not clearly established or maintained in T^C/T^C. By 1-s, +/+ allantoises exhibited signs of endothelialization in distal regions (inset, C, arrow), a feature that was not readily apparent in T^C/T^C. Abbreviations as in Fig. 1. Scale bar in F: 100 µm for A-F.