The extra-embryonic membranes of mammalian embryo are derived from
Trophoblast
Follicle cells
Formative cells
Inner cell mass
Which type of placenta is present in the early human embryo?
How many cleavages are completed in $16$ celled stage of egg.
$A$ : In human, ovum is alecithal type.
$R$ : It is almost free of yolk
Human eggs are
Zona pellucida of mammalian egg serves which of the following purpose