MP1:

MP1 (Midline Precursor 1) forms as an unpaired precursor from the mesectodermal cells along the ventral midline of the CNS.

In grasshoppers, the MP1 precursor is observed to divide once, producing two bilaterally symmetrical intersegmental interneurons; these neurons are involved in pioneering medial fascicles of the longitudinal connectives (Goodman and Spitzer, 1979; Goodman et al., 1979; Bate and Grunewald, 1981; Goodman et al., 1984).

In Drosophila, Bossing and Technau (1994) describe this clone as consisting of two bilateral neurons at the midline, anterior to the posterior commissure. Each neuron sends a bifurcating axon anterior and posterior for two to three segments in a medial fascicle of the longitudinal connectives. We generated 10 MP1 clones, 4 at stage 15, 2 at stage 16 and 4 at stage 17 (Fig. MP1). Our results are in agreement with Bossing and Technau (1994), but includes a projection anteriorly from the posteriorly projecting axon fascicle at stage 17 (Fig. MP1, and diagram).

References:

Bate, C. M., and Grunewald, E. B. (1981). Embryogenesis of an insect nervous system II: a second class of neuron precursor cells and the origin of the intersegmental connectives. J Embryol exp Morph 61: 317-30.

Bossing, T., and Technau, G. M. (1994). The fate of the CNS midline progenitors in Drosophila as revealed by a new method for single cell labeling. Development 120: 1895-1906.

Goodman, C. S., and Spitzer, N. C. (1979). Embryonic development of identified neurones: differentiation from neuroblast to neuron. Nature 280: 208-14.

Goodman, C. S., O'Shea, M., McCaman, R., and Spitzer, N.C. (1979). Embryonic development of identified neurons: temporal pattern of morphological and biochemical differentiation. Science 204: 1219-22.

Goodman, C. S., Bastiani, M., Doe, C. Q., du Lac, S., Helfand, S. L., Kuwada, J. Y., and Thomas, J. B. (1984). Cell recognition during neuronal development. Science 225: 1271-79.