4.Inventories

Inventories are comprised of unprocessed tissue, work-in-process, Avance® Nerve Graft, AxoGuard® Nerve Connector, AxoGuard Nerve Protector, Avive® Soft Tissue Membrane, AcroVal Neurosensory and Motor Testing System, AxoTouch® Two-Point Discriminator and supplies and are valued at the lower of cost (first-in, first-out) or net realizable value and consist of the following:

For the three months ended March 31, 2019 and 2018, the Company had inventory write-downs of $444 and $354 respectively.