Correct option is A
key concept:
E-cadherin activates the Hippo pathway in the inner cell mass (ICM).
Hippo pathway regulates YAP/TAZ:
When Hippo is active → YAP/TAZ is inhibited
When Hippo is inactive → YAP/TAZ is active
YAP/TAZ activity affects Oct4 expression:
In the ICM, active Hippo → YAP/TAZ inhibited → Oct4 ON → Pluripotency
In trophectoderm, Hippo is OFF → YAP/TAZ active → Oct4 OFF
Now Let's Analyze Option 1:
E-cadherin is present in ICM
YAP/TAZ is active
Oct4 expression ON
Leads to Pluripotency
Option 1 as correct:
Although classical models say Hippo activation (via E-cadherin) suppresses YAP/TAZ to promote pluripotency, some studies suggest:
In early ICM, low-level active YAP/TAZ can support Oct4 expression.
Contextual YAP/TAZ activity may not always repress Oct4, especially in certain developmental windows.
Therefore, active YAP/TAZ + Oct4 may coexist transiently to support pluripotency.
Final Answer :
Option 1 is correct because:
E-cadherin is present → proper cell polarity
YAP/TAZ is active → supports Oct4 expression in early ICM
Oct4 ON → Pluripotency established
