Question

Which of the following is common to both avian and mammalian development?

Options

• Holoblastic cleavage

• Primitive streak

• Trophoblast

• Yolk plug

Answer 1

Primitive streak

Explanation:

The primitive streak is a structure that forms during early embryonic development and is common to both avian and mammalian development. It marks the beginning of gastrulation and the formation of germ layers. In contrast, holoblastic cleavage is typical in mammals but not all birds; trophoblast is specific to mammals; thus, primitive streak is common to both groups.