The strongest dissecting microscope that I have been able to locate in our department is x20 (apparently I’m the only person who isn’t just running PCRs of computer data…). I’ve now acquired a fog mutant strain, and have suddenly become aware of the fact that all of the images on the internet of the differences between male and female worms are taken at much higher magnifications!
Is x20 powerful enough to differentiate between L4s/ young adults or male/ female-hermaphrodite worms? If so, does anyone know where I can find images illustrating the visible differences at lower magnifications? If not, what is the minimum magnification thought to be suitable for this purpose?
Thanks.
The Fitch lab does a lot of work with the male tail, and you can probably look up some publications.
Here’s a pic i found on their website:
http://www.nyu.edu/projects/fitch/Wildtyp.gif
At L4 the male tail will start to retract and it’ll sort of look like he’s wearing a sock on the tail. Adult males are generally a bit shorter (because of the retracted tail tip) and a bit slimmer than the hermaphrodites.
I just checked with my own dissecting scope and you can tell adult males from hermaphrodites with 20x (10x eyepiece and 2x zoom). However, it would be difficult to learn the differences, especially with larvae, using this magnification. You might want to start by going back and forth between a dissecting scope and a real microscope (even a crummy one from a teaching lab) to help yourself learn how to pick out the males at low mag.
Good luck, Janet
I agree that 20X should be sufficient, even for sexing L4s, but the illumination is pretty important - you need good oblique angle transmitted light to see worms clearly. If you have an adjustable mirror under the stage, and a diffuser, you should be able to get something decent. The male tail in L4 larvae looks like a bulge.
Abby