Very high power TEM of a stage 2, 2-cell embryo in vitro showing details of mitochondria (original magnification x35,000). Mitochondria are unchanged from those of mature oocytes.
S = smooth endoplasmic reticulum
From: Sathananthan and Trounson, 2000. Reproduced with permission of the publisher, Oxford University Press.
Keywords: mitochondria, oocyte, smooth endoplasmic reticulum, stage 2 embryo, two-cell embryo
Source: The Virtual Human Embryo.