Question

How are the reproductive characteristics of mammals different from those of aves?

Answer 1

	Mammals	Aves
1.	Mammals have paired sex organs, eggs are small with little or no yolk.	They are oviparous and lay eggs.
2.	They are viviparous and give birth to young ones.	The formation of the placenta is not seen. The embryo is nourished, by egg yolk. The egg has an abundant quantity of yolk.
3.	Formation of placenta is a special feature. The tissue connects the foetus to maternal tissues.