Ectoplacental cone

Evaluate the yolk sac, the ectoplacental cone, and the chorionic-allantoic membrane, and their morphological integrity. 

The integrity of the ectoplacental cone and chorionic-allantoic membrane are considered when assigning the yolk sac score. The ectoplacental cone should be attached to the base of the... 

Reduced scores are assigned when the caudal region deviates from this position. For instance, when there is a subtle to mild alteration of rotation, the caudal region can flare laterally towards the ectoplacental cone. 

If the degree of abnormal flaring is <50% of the distance to the ectoplacental cone, or there is a slight caudal bend, the embryo is scored a 4. >50% distance is scored a 3 (Fig. 2c, arrow). Also, if there is an obvious bend in the caudal region (Fig. 2d, arrow), or in cases when the embryo rotates in the opposite orientation (Fig. 2e, arrow) the score is assigned a 3. 

Abnormal expansion Ectoplacental cone inside YS Ectoplacental cone—Small Ectoplacental cone—Swollen Tachycardia Bradycardia No heartbeat Arrhythmia Embryo lethal NOT SCORED—Embryo damaged or missing... 

Fig. 7. (continued) The embryos are shown dissected free of the extraembryonic membranes with which they are cultured. (C) E7 embryos before and after culture. An E7 conceptus (including the visceral yolk sac and ectoplacental cone with, which it would be cultured) is shown on the left. This was refrigerated while littermates (center—with membranes as cultured right—dissected free of membranes) were cultured for 48 h. Scale bars for A, B, and C are all 1 mm. 

Fig. 9. As the decidua of the E7 conceptus is pulled apart, the ectoplacental cone of the embryo within can be seen.

Use the finer 5 forceps to snip open each deciduum and free the embryo Once free of the decidual tissue, remove the ectoplacental cone of embryos up to... 

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