Growth cone morphology and trajectory in the lumbosacral region of the chick embryo

Abstract

We quantitatively analyzed several features of orthogradely labeled peripheral growth cones in the lumbosacral region of the chick embryo. We compared motoneuron growth cones in regions where they appear to express specific directional preferences (the plexus region and regions where muscle nerves diverge from main nerve trunks), which we operationally defined as "decision regions," to motoneuron growth cones in other pathway regions (the spinal nerve, nerve trunk, and muscle nerve pathways) which we termed, for contrast, "non-decision region." We found that motoneuron growth cones are larger, more lamellepodial, and have more complex trajectories in decision regions. Sensory growth cone populations, which are thought to be dependent upon motoneurons for outgrowth (Landmesser, L., and M. Honig (1982) Soc. Neurosci. Abstr. 8: 929), do not enlarge or become more lamellepodial in motoneuron decision regions, suggesting that this local environment does not affect all species of growth cones equally and that the alterations in motoneuron growth cones in these regions may be relevant to their specific guidance. In addition, the resemblance between the sensory population and other closely fasciculating growth cones lends support to the suggestion that sensory neurons utilize motoneuron neurites as a substratum. We suggest that the convoluted trajectories, enlarged size, and more lamellepodial morphology of motoneuron growth cones in decision regions is either related directly to the presence of specific cues that guide motoneurons or to some aspect of this environment that allows them to respond to specific cues.

Retinal axon divergence in the optic chiasm: dynamics of growth cone behavior at the midline [published erratum appears in J Neurosci 1995 Mar;15(3):following table of contents]

“…A large number of studies have demonstrated in fixed dyelabeled preparations that simple streamlined growth cones are seen in straight paths and complex spread forms bearing filopodia are seen in decision regions (e.g., Tosney and Landmesser, 1985;Caudy and Bentley, 1986;Bovolenta and Mason, 1987;Nordlander, 1987;Holt, 1989;Norris and Kalil, 1990;Bovolenta and Dodd, 1991;Kim et al, 1991;Yaginuma et al, 1991;Wang et al, 1993). In the present study, we correlated form with behavior, within the single locale of the chiasm, and observed that the simple forms were common during advance and the complex forms during a pause in growth, in agreement with two other recent studies using video time-lapse imaging (Kaethner and Stuermer, 1992;Halloran and Kalil, 1994).…”

“…These studies have shown that in following precise trajectories, growth cones display dramatic alterations in their forms, thought to reflect the interactions that growth cones have with cellular and molecular cues in these regions. These analyses have also led to the conclusion that the variations in growth cone form are position specific, and that complex forms are more common in decision regions than in tracts, where streamlined forms predominate (e.g., Roberts and Taylor, 1983;Tosney and Landmesser, 1985;Caudy and Bentley, 1986;Bovolenta and Mason, 1987;Nordlander, 1987;Holt, 1989;Bovolenta and Dodd, 1990;Norris and Kalil, 1990;Kim et al, 199 1;Yaginuma et al, 1991;Wang et al, 1993).…”

Cellular Strategies of Axonal Pathfinding

“…These studies provided an index for analyzing growth cone morphology and behaviors in vivo. In the mid 1980s, numerous studies based on dye-labeling, static and dynamic imaging, and EM of growth cones in invertebrates and vertebrates convincingly showed that growth cone morphology mirrors three general behaviors that are related to substrata and cellular environments through which they grow (e.g., Tosney and Landmesser 1985;Caudy and Bentley 1986;Bovolenta and Mason 1987;Norris and Kalil 1990;Kim et al 1991). Torpedo-shaped growth cones, often with convex and concave lamellar "wings" extending from a central shaft, are observed during extension on axon bundles in tracts in vivo.…”

Regeneration of Vestibular Otolith Afferents after Ototoxic Damage

“…3c,e,g,h,j-n,r-t), digitiform appendages (Fig. 3g,l,n-p,r-v), or, more rarely, filamentous filopodia at the end of the fiber (Retzius, 1884;Ramon y Cajal, 1908;Fink and Morest, 1977;Tosney and Landmesser, 1985;Caudy and Bentley, 1986;Skaliora et al, 2000).…”