Microinjection arrangement

The spectral and topographic analysis of fluorescence associated with biologically active compounds (1-11) is of great interest in the study of cell metabolism (12,13,14) and cell-to-cell interactions (15,16,17). The dynamics of intracellular metabolism (]8,19,20,21") are better unraveled if transient shifts from steady state are"triggered via microinjections of metabolites, which requires instrumental arrangements allowing micro-manipulatory techniques (22,23,24). 

A representative arrangement for microdialysis sampling in anesthetized rats is shown in Figure 6.3. The microinjection pump should include features such as a pulse-free electronically controlled dc motor and should be precali-... 

Fig. 5. A typical arrangement of the equipment needed for the microinjection of fertilized one-cell eggs. A Agla micrometer S5ringe. B Liquid-paraffin-filled tube. C Left-hand micromanipulator. D Inverted microscope. E Base plate. F Camera (optional). G Left-hand instrument tube for holding pipet. H Microinjection chamber (depression slide) sitting on fixed stage. I Right-hand instrument tube for injection pipet. J Air-filled tube. K Glass 50-mL syringe. L Right-hand micromanipulator. M Video system (optional).

After the fourth (meridional) and fifth (equatorial) cleavages, the embryo comprises 32 cells, arranged in four tiers of eight cells (stage 6 of Nieuwkoop and Faber). The fates of these cells have been determined by microinjection of cell lineage markers (8,9), and the fate map of Dale and Slack is shown in Fig. 2. Notice that individual cells at this stage are far from restricted to a single fate, and that there may be considerable variation from embryo to embryo. 

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