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The establishment of the sensory nervous system of the antenna of the grasshopper Schistocerca gregaria was examined using immunocytochemical methods and in the light of the appendicular and articulated nature of this structure. The former is demonstrated first by the expression pattern of the segment polarity gene engrailed in the head neuromere(More)
 We have studied the embryonic development of the pars intercerebralis/central complex in the brain of the grasshopper using immunocytochemical and histochemical techniques. Expression of the cell-surface antigen lachesin reveals that the neuroblasts of the pars intercerebralis first differentiate from the neuroectoderm at around 26% of embryogenesis.(More)
The grasshopper antenna is an articulated appendage associated with the deutocerebral segment of the head. In the early embryo, the meristal annuli of the antenna represent segment borders and are also the site of differentiation of pioneer cells which found the dorsal and ventral peripheral nerve tracts to the brain. We report here on another set of cells(More)
The central body is a prominent neuropilar structure in the midbrain of the grasshopper and is characterized by a fan-shaped array of fiber columns, which are part of a chiasmal system linking anterior and posterior commissures. These columns are established during embryogenesis and comprise axons from cell clusters in the pars intercerebralis, which(More)
We have investigated the ontogenetic basis of locustatachykinin-like expression in a group of cells located in the pars intercerebralis of the grasshopper midbrain. These cells project fibers to the protocerebral bridge and the central body via a characteristic set of fiber bundles called the w, x, y, z tracts. Lineage analyses associate the immunoreactive(More)
Our analysis of head segmentation in the locust embryo reveals that the labrum is not apical as often interpreted but constitutes the topologically fused appendicular pair of appendages of the third head metamere. Using molecular, immunocytochemical and retrograde axonal staining methods we show that this metamere, the intercalary segment, is innervated by(More)
Embryonic development in the median domain of the brain of the grasshopper Schistocerca gregaria was investigated with immunohistochemical, histological, and intracellular dye injection techniques. The early head midline is divisible into a dorsal median domain and a ventral median domain based on the orientation of cell somata in each region. At 25% of(More)
The central complex is a major neuropilar structure in the insect brain whose distinctive, modular, neuroarchitecture in the grasshopper is exemplified by a bilateral set of four fibre bundles called the w, x, y and z tracts. These columns represent the stereotypic projection of axons from the pars intercerebralis into commissures of the central complex.(More)
The clypeo-labrum, or upper lip, of insects is intimately involved in feeding behavior and is accordingly endowed with a rich sensory apparatus. In the present study we map the temporal appearance of all major clusters of sensory cells on this structure in the locust during the first half of embryogenesis. The identities of these sensory cell clusters were(More)
We have studied the morphogenetic reorganization that occurs in the grasshopper brain during embryogenesis. We find that morphogenetic movements occur at three organizational levels during brain development. First, the entire developing brain changes its orientation with respect to the segmental chain of ventral ganglia. A 90 degrees shift in the attitude(More)