The highly orchestrated processes that generate the vertebrate inner ear from the otic placode provide an excellent and circumscribed testing ground for fundamental cellular and molecular mechanisms of development. The recent pace of discovery in developmental auditory biology has been unusually rapid,with hundreds of papers published in the past 4 years. This review summarizes studies addressing several key issues that shape our current thinking about inner ear development, with particular emphasis on early patterning events,sensory hair cell specification and planar cell polarity.

The formation of spherical aggregates of cells called embryoid bodies (EBs) is an indispensable step in many protocols in which embryonic stem (ES) cells are differentiated to other cell types. Appropriate morphology and embryo size are critical for the sequential developmental stages of naturally conceived embryos. Likewise, regulating the size of EBs and the timing of their formation is crucial for controlling the differentiation of ES cells within the EB. Existing methods of formation of EBs, however, are tedious or provide heterogeneously-sized EBs. Here we describe a microfluidic system for straightforward synchronized formation of uniform-sized EBs, the size of which can be controlled by changing the cross-sectional size of microchannels in the microfluidic device. The device consists of two microchannels separated by a semi-porous polycarbonate membrane treated to be resistant to cell adhesion. ES cells introduced into the upper channel self-aggregate to form uniformly-sized EBs. The semi-porous membrane also allows subsequent treatment of the non-attached EBs with different reagents from the lower channel without the need for wash out because of the compartmentalization afforded by the membrane. This method provides a simple yet robust means to control the formation of EBs and the subsequent differentiation of ES cells in a format compatible for ES cell processing on a chip.

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Alzheimer's disease is accompanied by progressive, time-dependent changes of three moieties of amyloid beta. In vitro models therefore should provide same conditions for more physiologic studies. Here we observed changes in the number of fibrils over time and studied the correlation between amyloid beta moieties and neurotoxicity. Although the number of fibrils increased dramatically, the change in neurotoxicity with time was small, suggesting that fibrils make little contribution to neurotoxicity. To study the neurotoxicity of diffusible moieties by regulating microenvironments, we created a bio-mimetic microfluidic system generating spatial gradients of diffusible oligomeric assemblies and assessed their effects on cultured neurons. We found amyloid beta exposure produced an atrophy effect and observed neurite extension during the differentiation of neural progenitor cells increased when cells were cultured with continuous flow. The results demonstrate the potential neurotoxicity of oligomeric assemblies and establish a prospective microfluidic platform for studying the neurotoxicity of amyloid beta.

Methods to detect immuno-labelled molecules at increasingly higher resolution, even when present at low levels, are revolutionizing immunohistochemistry (IHC). These technologies can be valuable for management and examination of rare patient tissue specimens, and for improved accuracy of early disease detection. The purpose of this mini-review is to highlight recent multiplexing methods that are candidates for more prevalent use in clinical research and potential translation to the clinic. Multiplex IHC methods, which permit identification of at least 3 and up to 30 discrete antigens, have been divided into whole section staining and spatially-patterned staining categories. Associated signal enhancement technologies that can enhance performance and throughput of multiplex IHC assays are also discussed. Each multiplex IHC technique, detailed herein, is associated with several advantages as well as tradeoffs that must be taken into consideration for proper evaluation and use of the methods.