High power SEM of the inside of a stage 3 embryo in vitro resulting from intracytoplasmic sperm injection of an ovum that was cultured for five days (original magnification x30,000). The elongated cells on the right are trophoblast cells.
From: Makabe et al., 2001. Reproduced with permission of the publisher, the Italian Journal of Anatomy & Embryology.
Keywords: stage 3 embryo, trophoblast cells
Source: The Virtual Human Embryo.