FIG. 4.

(A) Schematic illustration of the design of microfluidic chip that has three parallel gel regions, six gel filling ports, and two medium channels connected to four medium reservoirs. The device also contains a surrounding vacuum channel. Scale bar, 2 mm. (B) The device comprises a microfluidic layer on a polydimethylsiloxane membrane featuring two sets of two capped pillars (inset). The membrane is itself bonded to a coverslip. (C) Schematic illustration showing the final coculture arrangement: embedded in a hydrogel, muscle bundles that are wrapped around and exerted force to the pillars. They are innervated by neurospheres, which are placed in the opposite gel chamber separated by a 1-mm-wide gel region. (D) Schematic illustration showing the differentiation process of the ESCs into motor neurons (MNs). Row 2: Schematic illustration displaying the top and front views of the tissue in the microfluidic device. Row 3: Three-dimensional illustrations showing the version of the device used at the corresponding days. ChR2, and Channelrhodopsin-2; CNTF, ciliary neurotrophic factor; EBs, embryoid bodies; ESCs, embryonic stem cells; GDNF, glia-derived neurotrophic factors; HS, horse serum; RA, retinoic acid; SAG, smoothened agonist. Reproduced from Uzel et al.,⁴³¹ which is an open-access article distributed under the terms of the Creative Commons Attribution license. Color images are available online.