Fig. 14. TEM of the polar trophoblast of a mid blastocyst, stage 3 embryo, 96-120 hours post-insemination (original magnification x3,100). SL, secondary lysosome-like bodies; V, vacuole; ZP, zona pellucida. Arrowheads indicate apical tight junction regions. Left inset: Enlargement of an apical tight junction region (original magnification x12,800). Right inset: Thick section of the mid blastocyst showing the inner cell mass and the blastocystic cavity (original magnification x440).
(From: Gualtieri, Santella, and Dale, 1992. Reproduced with permission of the publisher, John Wiley & Sons.)