He returned the sword to its sheath.

Please look at my new bow case.

This insect's elytron has a very beautiful pattern.

When the myelin sheath of nerve cells is damaged, nerve transmission slows down.

This seed has a well-developed coleoptile.

The sarcolemma covers the muscle cells.

The leaf sheath of this plant is very long.

He has tendonitis and says his wrist hurts.

Do you know which insect this egg casing belongs to?

The myelin sheath protects nerve cells and helps transmit nerve signals.