CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($)	Jan. 31, 2018	Apr. 30, 2017
Current assets:
Cash and cash equivalents	$ 17,938,000	$ 46,799,000
Trade and other receivables	7,967,000	7,742,000
Inventories	14,218,000	33,099,000
Prepaid expenses	906,000	1,460,000
Total current assets	41,029,000	89,100,000
Property and equipment, net	26,325,000	26,515,000
Restricted cash	1,150,000	1,150,000
Other assets	1,353,000	1,347,000
Total assets	69,857,000	118,112,000
Current liabilities:
Accounts payable	1,911,000	5,779,000
Accrued clinical trial and related fees	5,503,000	4,558,000
Accrued payroll and related costs	3,876,000	6,084,000
Deferred revenue	6,633,000	28,500,000
Customer deposits	17,602,000	17,017,000
Other current liabilities	749,000	993,000
Total current liabilities	36,274,000	62,931,000
Deferred rent, less current portion	2,064,000	1,599,000
Commitments and contingencies
STOCKHOLDERS' EQUITY:
Preferred stock - $0.001 par value; authorized 5,000,000 shares; 1,647,760 issued and outstanding at January 31, 2018 and April 30, 2017, respectively	2,000	2,000
Common stock - $0.001 par value; authorized 500,000,000 shares; 45,257,180 and 44,014,040 issued and outstanding at January 31, 2018 and April 30, 2017, respectively	45,000	44,000
Additional paid-in-capital	593,621,000	590,971,000
Accumulated deficit	(562,149,000)	(537,435,000)
Total stockholders' equity	31,519,000	53,582,000
Total liabilities and stockholders' equity	$ 69,857,000	$ 118,112,000