Figure 3.—

Cytology of meiotic maturation in M. hapla. (A–F) Successive images from the same gonad stained with Hoescht 33258 that represent progression from oocytes just posterior to the spermatheca. The gonad was from a culture of strain VW9 infected with a low nematode innoculum. No sperm were seen in the spermatheca of this gonad. (A) Multiple oocytes arrested in metaphase I. (B) The last metaphase I oocyte (labeled M) is followed by an oocyte that appears to be in anaphase II. The following oocyte (C) appears to be arrested in telophase II with two pronuclei and a condensed polar body or polar nucleus. As the oocytes move toward the vagina, the two pronuclei are seen progressively closer and merge together (D–F). The polar nucleus or polar body from meiosis I is indicated by an arrowhead. In E, the polar body appears to be extruded from the cell and no polar body is apparent in F. Bar in A–F, 0.02 mm.