Alain Briot is our resident master printer. Until he responds let me try. In fact, indulge me.
Let me stray far from you particular case of B&W to the B&W prints derived from making monochromatic images of our colored world.
Let's start by seeing an image. Here, in the world of sight, light of various wavelengths excite the retina to form an image which the brain converts to a concept of color. Our cameras attempt to also capture that same light and also convert the resultant image in a representation that approximates what we perceive through our own eyes.
With digital cameras, this information is stored in a file within the limited colors of the devices manufactured world of color (Gamut). So some colors we see, such as some blues or purples, might not be represented so well in the files generated by the camera.
Now when this file goes to the computer the color data is in one world (or gamut), but the monitor may not mechanically be able to generate and display very well, or at all, all those hues present in the image captured in the camera's (gamut or) unique world of color.
So software allows some perceptual remapping of colors so that to the eye, the picture taken by the camera ultimately appears identical to that seen with the naked eye.
Still there's one further step: the picture can't stay just in the computer.
We want a print. Trouble is that the printer also has its own unusual and unique gamut, (or particular world of color), and even can print hues, fore example some greens perhaps, that the monitor can never show. So once again, translation and remapping of colors is done to create in the final print, a vivid life-like image.
Well, with most B&W images, one is actually creating a set of artificial tones in an image that really was much more limited in variation of blackness or whiteness. It is like creating in an object an extra patina of brilliantly fine shading that adds detail to the already profound shading of the luminance values in the picture.
Every different color can be made to appear as bright or dark as you happen to wish. you can convert to B&W in CMYK, RGB or LAB and have slightly different elements of control as to what becomes dark, grey and white and everything in between. All one is doing is changing how one perceives the some brightness values of an image (i.e. it's amount of black or white) by making your own choices on how should the pink of the skin be represented: a brightness of 200 or perhaps a darkness of 60? It is entirely your choice. The great advantage is that a dress, for example with flowers having identical brightness, would show as an almost uniform grey with hardly any definition of the pattern. By assigning to the flower and leaves different luminance values, suddenly the flower pattern pops out and the dress looks pretty again.
Now lets jump to the electron microscope picture. Here, as I understand it, there is only a grey scale image, the points are all somewhere between say 20 and 200 in brightness. There is however no color information at all.
All you can do is record that image and then try not to add more noise before printing. There is no color to take advantage of to enhance your picture. Still there are several things you can do which you would do with any image: define black point, white point and mid point so as to utilize the dynamic range of your printer effectively. Just doing this can already make your image, yes even an E.M. image come to life. Next one might consider a curve adjustment to make the picture "pop". A modest "S" shaped curve would be tried, Then the percent of this layer would be decreased to get the optimum result.
All this can be done in any color space or in monochrome. I would use adobe RGB but make a note with the submission.
I went through a lot just to say it doesn't make any difference for your E.M. picture, but this was an opportunity to introduce to some the concepts of machine specific worlds of color, or "gamuts" and our need to have colors remapped between these worlds in order to create a lifelike image in any machine: monitor, projector or printer.
Having said that, let's go back to your image from the electron microscope which is sitting there monochromatic. You might very well choose to apply a "hint of tint". Since you are in RGB it is easy to do that with any one of the color adjusting layers of photoshop. There is no reason not to do so, since the various membranes or particles imaged most like are not gray in the first place.
The next manipulation is more subtle. If you go to Reindeer Graphics, you could download, at a price, some image analysis software which could create pseudo colors according to, for example, the rate at which an edge or a junction changes density or even the rate at which the rate of change changes. (ie 2cd derivative). Now they have many more subtle and sophisticated image enhancing tricks which you can apply.
This can sometimes make detail, otherwise obfuscated by granularity for example, to suddenly be revealed. The results can be delivered in color or, (as in the case of assigning the real color information of RGB images to B&W), you can assign the new derived detail to be overlaid on to your grayscale image, to appear as various shades of grey.
So, your original simple question about color space was used to indicate a myriad of ways of delivering a more useful image.
Asher