LM of a stage 2 embryo on day 4 in vitro showing disappearing cell membranes (compaction 5). Nine to ten nuclei and a variable number of nucleoli are visible. This morula did not complete further cell divisions until after compaction was finished and cavitation had begun.
From: Veeck and Zaninovic´, 2003. Reproduced with permission of the publisher, Taylor & Francis Group.
Keywords: blastomere nucleolus, blastomere nucleus, cavitation, compacting embryo, disappearing cell membranes of blastomeres, exterior part of blastomere cell membrane, morula, stage 2 embryo, subzonal space, zona pellucida
Source: The Virtual Human Embryo.