Unmyelinated nerve fibre is enclosed by a/an ‘X’ that does not form a myelin sheath around the ‘Y’, and is commonly found in ‘Z’ and the somatic neural systems. Identify ‘X’, ‘Y’ and ‘Z’.

	X	Y	Z
1.	Schwann cell	axon	autonomous
2.	mast cell	cell body	central
3.	oligodendrocytes	axon	sympathetic
4.	goblet cell	dendrite	parasympathetic