4. PROPERTY AND EQUIPMENT (Details) - USD ($)	Jul. 31, 2015	Apr. 30, 2015
Property, Plant and Equipment [Abstract]
Leasehold improvements	$ 1,564,000	$ 1,538,000
Laboratory equipment	6,112,000	5,965,000
Furniture, fixtures, office equipment and software	4,023,000	3,991,000
Construction-in-progress	15,119,000	11,819,000
Property, gross	26,818,000	23,313,000
Less accumulated depreciation and amortization	(8,423,000)	(8,189,000)
Property and equipment, net	$ 18,395,000	$ 15,124,000