Synapse formation on quail trochlear neurons transplanted in duck embryos before naturally occurring motor neuron death

Abstract

About half of the trochlear motor neurons in duck and quail embryos die during normal development. In a previous study the role of target muscle in controlling the number of surviving motor neurons was investigated by reducing the number of neurons innervating the muscle. This was accomplished by removing the midbrain of the duck embryo and grafting in its place the midbrain of the quail embryo before motor neuron death begins. It was observed that the number of surviving trochlear motor neurons in the quail-duck chimera embryos was not significantly different from that of the normal quail. The present investigation was undertaken to determine whether trochlear motor neurons in the chimera embryos received afferent synapses. Brains of duck, quail and chimera embryos on days 16 and 20 were processed for electron microscopical observations. Synapses formed on motor neurons of the chimera embryos. Surprisingly, synapses on motor neurons of quail differed from those of duck, both qualitatively and quantitatively. Synapses on the motor neurons of the chimera embryos developed in a fashion similar to that for the duck motor neurons. Our failure to rescue trochlear motor neurons in the chimera embryos suggests that the developing motor neurons may respond to a larger target muscle only if they received a normal complement of afferent synaptic input.

Naturally occurring motoneuron cell death in rat upper respiratory tract motor nuclei: A histological, fast dil and immunocytochemical study in the nucleus ambiguus

“…This period of increase in afferent neuronal input to NA coincides with the occurrence of MCD. As MCD is responsive, in part, to signals from afferent neurons (Furber et al, 1987;Sohal et al, 1990;Clarke, 1992), the observed proliferation of afferent input to NA motoneurons at this time may play a modulatory role in the course of cell death.…”

The Cells that Fill the Bill: Neural Crest and the Evolution of Craniofacial Development

“…One of the newly emerging avian models for analyzing the distinct functions of neural-crest-derived mesenchyme during craniofacial development is the quail-duck chimeric transplantation system (Schneider and Helms, 2003;Tucker and Lumsden, 2004;Eames and Schneider, 2005;Schneider, 2005). The domestic duck has a long history of being included in avian chimeras as a way to study those patterning mechanisms that make embryos morphologically distinct (Waddington, 1930(Waddington, , 1932Hampe, 1957;Zwilling, 1959;Dhouailly, 1967Dhouailly, , 1970Pautou, 1968;Sohal, 1976;Sohal et al, 1985Sohal et al, , 1990Sohal, 1986, 1987). But the combination of Japanese quail (Coturnix coturnix japonica) and White Pekin duck (Anas platyrhynchos) as donors and/or hosts adds value for at least four reasons (Lwigale and Schneider, 2008).…”

“…The domestic duck has a long history of being included in avian chimeras as a way to study those patterning mechanisms that make embryos morphologically distinct (Waddington, 1930(Waddington, , 1932Hampe, 1957;Zwilling, 1959;Dhouailly, 1967Dhouailly, , 1970Pautou, 1968;Sohal, 1976;Sohal et al, 1985Sohal et al, , 1990Sohal, 1986, 1987). But the combination of Japanese quail (Coturnix coturnix japonica) and White Pekin duck (Anas platyrhynchos) as donors and/or hosts adds value for at least four reasons (Lwigale and Schneider, 2008).…”

Neural crest and the origin of species‐specific pattern

“…Moreover, determining mechanisms of species‐specific pattern was not really the primary goal of most studies that employed quail‐chick chimeras. In contrast, other experiments using avian chimeras have included domestic duck as a way to identify those patterning mechanisms that generate species‐specific differences (Dhouailly, ; Hampe, ; Lwigale & Schneider, ; Pautou, ; Schneider & Helms, ; Sohal, ; Sohal et al, ; Sohal et al, ; Tucker & Lumsden, ; Waddington, ; Waddington, ; Yamashita & Sohal, , Yamashita & Sohal, ; Zwilling, ). Additional studies on species‐specific size and control of scaling have also included chimeras between quail and emu (Hall et al, ), quail and zebra finch (Chen, Balaban, & Jarvis, ), and chick and zebra finch (Uygur et al, ).…”