Stalk with which ovules remain attached to placenta is called

In the diagram given above, parts labelled as $\text{'}\mathrm{A}\text{'}, \text{'}\mathrm{B}\text{'}, \text{'}\mathrm{C}\text{'}, \text{'}\mathrm{D}\text{'}, \text{'}\mathrm{E}\text{'}$ and $\text{'}\mathrm{F}\text{'}$ are respectively identified as

Caruncle is derived from-