CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($)	Oct. 31, 2016	Apr. 30, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 49,055,000	$ 61,412,000
Trade and other receivables	6,066,000	2,859,000
Inventories	25,924,000	16,186,000
Prepaid expenses and other current assets	1,711,000	1,351,000
Total current assets	82,756,000	81,808,000
Property and equipment, net	23,957,000	24,302,000
Restricted cash	600,000	600,000
Other assets	2,624,000	2,333,000
TOTAL ASSETS	109,937,000	109,043,000
CURRENT LIABILITIES:
Accounts payable	11,572,000	8,429,000
Accrued clinical trial and related fees	3,639,000	7,594,000
Accrued payroll and related costs	5,280,000	5,821,000
Deferred revenue	17,980,000	10,030,000
Customer deposits	26,928,000	24,212,000
Other current liabilities	1,012,000	1,488,000
Total current liabilities	66,411,000	57,574,000
Deferred rent, less current portion	1,347,000	1,395,000
Commitments and contingencies
STOCKHOLDERS' EQUITY:
Preferred stock - $0.001 par value; authorized 5,000,000 shares; 1,647,760 and 1,577,440 issued and outstanding at October 31, 2016 and April 30, 2016, respectively	2,000	2,000
Common stock-$0.001 par value; authorized 500,000,000 shares; 251,765,279 and 236,930,485 issued and outstanding at October 31, 2016 and April 30, 2016 , respectively	252,000	237,000
Additional paid-in-capital	566,314,000	559,111,000
Accumulated deficit	(524,389,000)	(509,276,000)
Total stockholders' equity	42,179,000	50,074,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 109,937,000	$ 109,043,000