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Inquiry about a long-lasting, local anaesthetic
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trees. The neurons of Fig. 2 are of the type I observed most frequently; I regard them as the 'cellulas estrelladas' of Lorente de Nb [3] and as the neurons belonging to classes Ia and Ib described by Woolsey et al. [ 5]. They send most of their dendrites into the hollow of the barrel and give rise to a descending axon with several collaterals that tend to ramify within their 'home-barrel' (C and D). I t h a n k Professor H. Van der Loos for his help with the identification of the barrelfield. I am very grateful to Miss A. Schiiz for the negative of the left photo of Fig. 1 and to Mrs D. Stoll for the excellent preparations. (Received January 15th, 1976) (Accepted February 6th, 1976)
HANS STEFFEN Max-Planck-Institut ffir b!ologische Kybernetik, Spemannstr. 38, D-74 TUBINGEN, G.F.R.
1 Colonnier, M., The tangential organization of the visual cortex, J. Anat. (Lond.), 98 (1964) 205--242. 2 Killackey, H.P., Anatomical evidence for cortical subdivisions based on vertically discrete thalamic projections from the ventral posterior nucleus to cortical barrels in the rat, Brain Res., 51 (1973) 326--331. 3 Lorente de N5, R., La corteza cerebral del ratSn, Trab. Lab. Invest. Biol. (Madrid), 20 (1922) 41--78. 4 Woolsey, T.A., Dierker, M.L., and Wann, D.F., Mouse SmI cortex: qualitative and quantitative classification of Golgi-impregnated barrel-neurons, Proc. nat. Acad. Sci. (Wash.), 72 (1975) 2165--2169. 5 Woolsey, T.A., and Van der Loos, H., The structural organization of layer IV in the somatosensory region (SI) of the mouse cerebral cortex, Brain Res., 17 (1970) 205--242.
Inquiry about a long-lasting, local anaesthetic Sir, I am writing to inquire about means of reversibly blocking the function of sensory nerves in small laboratory animals for periods of several days to weeks. A local anaesthetic called Zyljectin (Abbott), which seemed to meet our demands, is no longer available. Presently, we are trying to achieve the desired functional block with Xylocaine but fear that the necessary repeated injections may cause accidental damage or infection of the nerves. We would greatly appreciate any suggestions from y o u r readers. (February 10th, 1976)
F R A N K L. RICE Institut d 'Anatomie Universit$ de L a u s a n n e rue d u B u g n o n 9 CH 1011 Lausanne, S w i t z e r l a n d
trees. The neurons of Fig. 2 are of the type I observed most frequently; I regard them as the 'cellulas estrelladas' of Lorente de Nb [3] and as the neurons belonging to classes Ia and Ib described by Woolsey et al. [ 5]. They send most of their dendrites into the hollow of the barrel and give rise to a descending axon with several collaterals that tend to ramify within their 'home-barrel' (C and D). I t h a n k Professor H. Van der Loos for his help with the identification of the barrelfield. I am very grateful to Miss A. Schiiz for the negative of the left photo of Fig. 1 and to Mrs D. Stoll for the excellent preparations. (Received January 15th, 1976) (Accepted February 6th, 1976)
HANS STEFFEN Max-Planck-Institut ffir b!ologische Kybernetik, Spemannstr. 38, D-74 TUBINGEN, G.F.R.
1 Colonnier, M., The tangential organization of the visual cortex, J. Anat. (Lond.), 98 (1964) 205--242. 2 Killackey, H.P., Anatomical evidence for cortical subdivisions based on vertically discrete thalamic projections from the ventral posterior nucleus to cortical barrels in the rat, Brain Res., 51 (1973) 326--331. 3 Lorente de N5, R., La corteza cerebral del ratSn, Trab. Lab. Invest. Biol. (Madrid), 20 (1922) 41--78. 4 Woolsey, T.A., Dierker, M.L., and Wann, D.F., Mouse SmI cortex: qualitative and quantitative classification of Golgi-impregnated barrel-neurons, Proc. nat. Acad. Sci. (Wash.), 72 (1975) 2165--2169. 5 Woolsey, T.A., and Van der Loos, H., The structural organization of layer IV in the somatosensory region (SI) of the mouse cerebral cortex, Brain Res., 17 (1970) 205--242.
Inquiry about a long-lasting, local anaesthetic Sir, I am writing to inquire about means of reversibly blocking the function of sensory nerves in small laboratory animals for periods of several days to weeks. A local anaesthetic called Zyljectin (Abbott), which seemed to meet our demands, is no longer available. Presently, we are trying to achieve the desired functional block with Xylocaine but fear that the necessary repeated injections may cause accidental damage or infection of the nerves. We would greatly appreciate any suggestions from y o u r readers. (February 10th, 1976)
F R A N K L. RICE Institut d 'Anatomie Universit$ de L a u s a n n e rue d u B u g n o n 9 CH 1011 Lausanne, S w i t z e r l a n d