Implantation occurs at the stage of: (A) Zygote, (B) Morula, (C) Blastocyst, (D) Primary villi
Answer is C. C i.e. Blastocyst- Barrier is provided by fusion / feilin (not Ach)Q. Fusion reduce the membrane potential of ovum that prevents polyspermy by not allowing the others sperms to enter.- Morula is a 16 cell stage, surrounded by zona pellucida. Barrier is provided by fusiotVfetilin.QImplantation occurs at the stage of blasto cystQ.