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The inner ear of the mouse develops from a roughly spherical epithelial vesicle, the otocyst, which undergoes a series of complex shape changes to produce the functionally important parts of an adult inner ear; in particular, a coiled cochlea--which houses the auditory apparatus, a saccule and utricle containing sensors of gravity and linear acceleration,(More)
The epithelium lining the inner ear contains a large number of differentiated cell types, arranged in precise patterns. Once the otocyst has closed, do the cells differentiate according to mechanisms intrinsic to the epithelium or are they dependent on external influences? In particular, are they governed by signals from the surrounding periotic mesenchyme?(More)
How is the timing of nerve outgrowth controlled during development? This question has been examined by grafting early limb buds between chick embryos of different ages, before innervation, and assessing the morphological pattern of nerves at later stages. Grafted limbs continued to develop according to their own timetable and were invaded by nerves from the(More)
The possible role of calcium and a calcium-activated neutral protease (CANP) in the reorganisation of mature mammalian neuromuscular junctions was studied in the sternocostalis muscle in rats. After the well-documented loss of polyneuronal innervation has occurred, the remaining single mature nerve ending continues to change its terminal branching pattern(More)
To what extent do motor and sensory nerve fibres depend on one another for guidance during the development of peripheral nerve patterns? This question has been examined by looking at the paths taken by sensory nerve fibres growing into the embryonic chick wing in the absence of motor axons. The precursors of the motoneurones were destroyed by irradiating(More)
Coherent laser beam addition offers the potential for extremely bright optical sources by combining the power from many individual lasers. Binary-optical elements-surface-relief structures etched into optical substrates by integrated-circuit techniques-have been successfully employed in three optical beam addition systems. The techniques can produce(More)
Using in situ hybridisation we have determined the distribution of expression of 2ar (also known as osteopontin, bone sialoprotein 1 or 44-kDa bone phosphoprotein) in the developing mouse inner ear. We have identified several discrete sites, both osteogenic and non-osteogenic, that express 2ar from embryonic day 16.5 (E16.5). In addition to the regions of(More)
What constrains growing nerves to follow the paths they take during the development of peripheral nerve patterns? This paper examines two, related, topics concerning the pathways taken by sensory nerve fibres in the embryo chick wing: the constraints imposed on the nerves by limb tissues; and the timing of axon outgrowth. Sensory ganglia from 7-day-old(More)