In order to work efficiently with extracted worms you, first and foremost, need a high quality compound microscope. Ideally it should have interference contrast (DIC or Nomarski) and if possible also phase contrast (good to observe sensory hairs and cilia, and also sperm cells). The microscope should have a range of objectives (e.g. 4x, 10x, 20x, 40x, and 100x oil immersion), to observe details at different scales. These creatures are very small (usually only about 1mm long), so high magnification is essential to reveal anatomical details.

A good squeeze preparation is essential to immobilize the worms and to visualize the various internal structures (see pictures), especially in bigger species. I generally use plasticine (or children's modeling clay) to make small feet on the corners on a cover slip (my favorite size is 21x26 mm). Then I place the cover slip down on a drop containing a worm on a microscope slide, and gently press down the corners. Be sure to put enough water initially, so that the worm does not get squeezed too much by the capillary force on the cover slip. Then use a corner of a filter paper to remove excess water, while you observe the worm in a binocular (preferably under transmitted light). Once the worms is lightly squeezed you can place it under the compound microscope and start observing and documenting the worm.

making a squeeze preparation (the brown bar is a piece of plasticine)

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith