LM of a stage 1b embryo in vitro with two pronuclei of approximate equal size. Nucleoli begin to align at adjacent areas within each pronucleus. The pronuclei have not yet aligned in the polar axis.
From: Veeck and Zaninovic´, 2003. Reproduced with permission of the publisher, Taylor & Francis Group.
Keywords: nucleolus, pronucleus, stage 1b embryo
Source: The Virtual Human Embryo.