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Neurite morphogenesis of identified visual interneurons and its relationship to photoreceptor synaptogenesis in the flies, Musca domestica and Drosophila melanogaster.
- Source :
-
The European journal of neuroscience [Eur J Neurosci] 2000 Apr; Vol. 12 (4), pp. 1342-56. - Publication Year :
- 2000
-
Abstract
- The first neuropile, or lamina, of the fly's optic lobe comprises a model set of identified neurons that are arrayed in cylindrical modules, called cartridges. The cartridge acquires adult form only in the second half of the fly's pupal life. All cells are by then correctly located within each of the lamina's cartridges (Drosophila, Musca), becoming invested by glial cells after 75% of pupal development (P + 75%). In adult cartridges, two lamina cells, L1 and L2, receive input from photoreceptor terminals R1-R6, at so-called tetrad synapses that form in the pupa when these cells' dendrites contact R1-R6. Single-section electron microscopy (EM, Drosophila) and serial-EM reconstructions of L1 and L2 (Musca) reveal relationships between the morphogenesis of L1/L2 dendrites and the formation of tetrads. Neurite outgrowth is initially (P + 55%) random and neurites are unbranched; many neurites invaginate surrounding terminals of R1-R6 but, later, embrace the outer surfaces of these. The maximum profusion of neurites at P + 74% coincides with peak numbers of nascent tetrads; neurites then branch vertically, in the lamina's depth. Later, neurites failing to reach R1-R6's outer surfaces regress. Down the length of their axons, L1 and L2's neurites initially form a random sequence, L1 partnering L1 as often as L2, etc., but beginning at P + 74%, L1 partners L2, and L2 partners L1, with progressive strictness. L1 has more neurites overall than L2. These observations are consistent with the following hypotheses: a neurite only survives if it contacts a presynaptic site; a synapse only survives if it progressively acquires the appropriate number and combination of postsynaptic neurites, culminating in a tetrad; an interaction exists between the neurites of L1 and L2, so that the growth of one respects the pattern of growth of the other.
- Subjects :
- Animals
Cell Size physiology
Dendrites physiology
Dendrites ultrastructure
Drosophila melanogaster
Growth Cones physiology
Growth Cones ultrastructure
Houseflies
Image Processing, Computer-Assisted
Interneurons physiology
Microscopy, Electron
Neurites physiology
Neuropil ultrastructure
Optic Lobe, Nonmammalian cytology
Photoreceptor Cells, Invertebrate physiology
Pupa cytology
Synapses physiology
Visual Pathways cytology
Visual Pathways growth & development
Interneurons ultrastructure
Neurites ultrastructure
Photoreceptor Cells, Invertebrate ultrastructure
Synapses ultrastructure
Subjects
Details
- Language :
- English
- ISSN :
- 0953-816X
- Volume :
- 12
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The European journal of neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 10762363
- Full Text :
- https://doi.org/10.1046/j.1460-9568.2000.00033.x