Is there anyone who knows how to identify the newly fertilized embryo, and how to measure the diameter of pronucleus of male?
I would highly recommend reading a paper by McNally et al. (2005), Dev Bio 282 (218-230). They very carefully detail all of the events which occur at this timepoint. The easiest way to view this process is either by Nomarski at 40X, or by using a gfp or rfp conjugated to the histones. The newly fertilized embryo will have just passed out of the spermatheca. With a marked histone strain you can observe the progression of meiosis I and II, and then observe directly the decondensation to pronuclei. Failing that, you can observe under Nomarski, the first or second embryo out of the spermatheca and wait for the appearance of the pronuclei. In order to make measurements, we generally take a picture of the DIC image, then take a pic at the same magnification of a haemocytometer, then overlay the two images.