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. Author manuscript; available in PMC: 2009 Feb 15.
Published in final edited form as: Dev Biol. 2007 Dec 15;314(2):362–375. doi: 10.1016/j.ydbio.2007.12.007

Fig. 8. Determination of the onset of trophoblast cell invasion following hypoxia-activation.

Fig. 8

Maternal hypoxia exposure (equivalent to 11% oxygen) was initiated on gestation day 6.5 and continued to days 10.5, 11.5, 12.5, or 13.5 of gestation when animals were sacrificed. Gestationally matched pair-fed rats exposed to ambient conditions were used as controls. Invasive trophoblast cells were monitored by cytokeratin immunostaining. Panels A-H, show representative cytokeratin-immunostained sections from placentation sites from gestation day 10.5 (panels A and B), day 11.5 (panels C and D), day 12.5 (panels E and F), and day 13.5 (panels G and H). Panels A, C, E, and G show representative cytokeratin-immunostained sections from placentation sites of pair-fed controls. Panels B, D, F, and H show representative cytokeratin-immunostained sections from hypoxia exposed placentation sites. Chromogen: AEC; counterstain: hematoxylin; scale bar = 0.5 mm. Panel I, quantification of the depth of cytokeratin positive cell penetration into the uterine mesometrial vasculature. Values are means ± the standard error of each mean (n=5 for each group). The asterisk indicates a significant difference between pair-fed normoxia controls and maternal hypoxia exposed placentation sites, P<0.0001. Abbreviations: PF-N, pair-fed normoxia; HYP, maternal hypoxia; Invasion Index, see Materials and Methods or legend to Fig. 3. Please note that hypoxia stimulated trophoblast invasion into the uterine mesometrial compartment is initiated between days 12.5 and 13.5 of gestation.