Kathryn W. Tosney

      Methods Developed

We have developed methods as we needed them to examine developing tissues, their interactions, and the molecular basis of guidance. For instance, to analyze general guidance cues at both cellular and molecular levels, we developed hybrid culture preparations that retain embryonic tissue relationships but provide greater accessibility for observations and for interventions with surgery and exogenous chemicals.

For analysis at the cellular level, we have used our culture systems to distinguish between two classes of axonal guidance cues, diffusible and contact-mediated. These two classes differ cellularly and implicate different types of molecules. Diffusible cues emanate from a distant source and attract or repel axons. In contrast, contact-mediate interactions implicate molecules on cellular surfaces or in the extracellular matrix.

Using our culture preparations, we have shown that sensory and motor axons are guided by both diffusible and contact-mediated interactions (Hotary and Tosney, 1996).

    illustrates a culture preparation that retains embryonic tissue relations but supplies great accessibility. We explant portions of embryos large enough to simulate a real embryonic environment but simple enough to support detailed analysis. Living neurons can be dissociated and sprinkled on such preparations, and their subsequent behavior assessed, thereby using the neurons themselves as the probes for neuronal guidance cues.


  • Krull, C. and K. Tosney (2008). Embryo Slices and Strips: Guidance and Adhesion Assays in the Avian Embryo. In Methods in Cell Biology: New Methods in Avian Embryology. Vol 87. ed.: M. Bronner-Fraser, pp. 99-115

  • Tosney KW, Oakley R, Champion M, Bodley L, Sexton S and Hotary K (1996) Somite strips: An embryo fillet preparation. In Methods in Cell Biology: Methods in Avian Embryology. 51:93-108 ed: M. Bronner-Fraser.

  • Hotary KB, Landmesser LT and Tosney KW (1996). Embryo slices. In Methods in Cell Biology: Methods in Avian Embryology. 51: 109-124. ed: M. Bronner-Fraser.

  • Tosney KW (1988). How to dissect an egg. Fine Sci.Points 2: 1-4.

  • Tosney KW and Landmesser LT (1986). Neurites and growth cones in the chick embryo: enhanced tissue preservation and visualization of HRP-labeled subpopulations in serial 25 µm plastic sections cut on a rotary microtome. J. Histochem. Cytochem. 34:953-957.