Very high power TEM of the interpronuclear zone in a stage 1b embryo in vitro, 17 hours post-insemination (original magnification x33,810). The narrow region of cytoplasm contains mitochondria (M) associated with smaller elements of the smooth endoplasmic reticulum. The mitochondria have dense stromae and few cristae.
PnM = pronuclear membrane
Pn = pronucleus
From: Sathananthan and Trounson, 1985. Reproduced with permission of the publisher, John Wiley & Sons.
Keywords: cristae, interpronuclear zone, mitochondria, smooth endoplasmic reticulum, stroma(e)
Source: The Virtual Human Embryo.