The spleen develops from which embryonic germ layer?

Identify the tissue shown in the diagram and match it with its characteristics and location.

Structural organisation in animals attains different levels as cell-organ-organ system. What is missing in this chain? Mention the significance of such an organisation.

Identify the correctly matched pair/pairs of the germ layers and their derivatives.
$A$. Ectoderm-Epidermis
$B$. Endoderm-Dermis
$C$. Mesoderm-Muscles
$D$. Mesoderm-Notochord
$E$. Endoderm-Enamel of teeth

In rabbit,the uterus is

Cockroach and earthworm have a common type of: