MICROCUTTING OF LIVING BRAIN-SLICES BY A PULSED ULTRAFINE WATER-JET WHICH ALLOWS SIMULTANEOUS ELECTROPHYSIOLOGICAL RECORDINGS (MICROMINGOTOME)

Up to now microsurgical dissections in living nervous tissue (e.g. in slices or cell cultures) are performed either by micro-scalpels or by laser beams. As an alternative technique a device for cutting with an ultrafine pulsed water jet was developed to allow precise, visually co ntroled dissections in neuronal circuits even during electrophysiologi cal recordings. Water is ejected by pressure (20-30 bar) from patch pi pettes with tip diameters of 10-12 mu m. By means of a piezo-element t he pipette and the water jet are forced to oscillate vertically with a frequency of 200-400 Hz with an adjustable amplitude. These oscillati ons facilitate the transsection of neuronal connections even in thick slice preparations. Best results were obtained when the tip of the pip ette was about 500 mu m above the surface of the submerged slice tissu e. This micromingotome offers the following advantages: (i) histologic al studies show that the water jet cleans the cutting surface, thus av oiding debris and its uncontrolable effects on cells underneath; (ii) the arrangement enables ongoing electrophysiological recordings from h ippocampal slices during the cutting procedure and thus facilitates st udies of the functions of neuronal connections; (iii) the device allow s even disconnection in cultured nervous tissue overgrowing polyamid g rids with 50 mu m wide meshes. (C) 1998 Elsevier Science B.V. All righ ts reserved.