The Zeiss Axiovert 200 Inverted Microscope is built for examination of tissue culture flasks, Petri dishes, microtiter plates, etc., in transmitted and reflected light. It can be used for bright field, phase contrast, differential interference contrast, and epi-fluorescence techniques. We use it in our laboratory primarily for microinjection of DNA into the syncytial germ line in the distal gonads of
C. elegans in order to generate transgenic worms, and to inject dsRNA to induce RNAi. We have accessories for microinjection connected to this microscope. This microscope has a sturdy stand providing multiple attachment possibilities for micro-manipulation. In our case, we have the Narishige 3D Hydraulic Coarse/Fine Micromanipulator (a joystick-controlled hydraulic coarse/fine micromanipulator for positioning of our Eppendorf microinjector under the microscope), the Eppendorf FemtoJet (for injection), and a small Sony television so others can view while a person does the manipulation.
It is a relatively large microscope. The dimensions are 295 x 805 x 707 mm and the weight is approximately 26 kg. As for objectives, we have two of them on this instrument. One of them has the 10X (objective magnification) and 0.25 (numerical aperture), allowing overall visual magnification of 160X (10X objective magnification x 10X eyepiece magnification x 1.6X Optovar magnification). The second objective is the 40X/1.3 oil objective. We use the small 10X objective to locate the worm and the 40X objective for the microinjection of DNA into the worm gonads. The image quality is superb, with great contrast and brightness. At the 40X objective, we can clearly see the syncytial gonads with amazing contrast.
Some of the major features of this microscope are: ICS optics for image creation; a very nice LCD display located at the top of instrument (a two line display showing objective position, magnification and contrasting technique, and lamp brightness); an amazing, high quality 25 mm field of view; 6-position nosepiece; 5-position reflector turrent for epifluorescence; 6-position condensor turrent (phase and interference contrast); changeable aperture diaphragm and luminous-field diaphragm sliders in reflected light; fluorescence shutter; and an illuminator (a 100 W Halogen light bulb). Other features include a toggle switch for brightness control of the halogen illuminator, and a focusing drive which consists of a big knob for coarse adjustment and a small knob for fine adjustment.
The microscope stage is very spacious and includes a specimen holder for microscope slides. We have our worms immobilized on cover slips with a thin layer of agarose; the slips sit on top of the slides. Another unique feature of the stage is that it can be rotated 360 degrees, making manipulation very easy without having to actually move the slides themselves. Another unique feature is the Light Manager, which automatically sets the illumination intensity of the halogen illuminator to the most recently saved value for each objective position. Also, when changing objectives, the lamp voltage is reduced automatically to avoid glare.