mostly collagen and some calcium phosphate
Answer:
Companion cell is a type of specialized parenchyma cell, which is located in the phloem of the flowering plants.
Each of the companion cell is usually associated with the sieve element. The main function of the companion cell is uncertain but it regulates the activity of sieve tube.
It plays a major role in the loading and unloading of the sugar molecules into the sieve element. As the sieve tubes do not have nucleus and ribosomes so they need companion cell to help in the transportation of sugar molecules.
I'd have to go with the first option, stags have more prominent antlers than does
Marker/Recognition proteins extend across the cell membrane and serve to identify the cell. The immune system uses these proteins to tell good cells from foreign invaders.
