Figure 6.

Examples of mitochondria and endoplasmic reticulum (ER) arrangements in human oocytes. The atypical mitochondria with transversal or arc-like cristae forming small clusters in immature oocytes (A–C). Overview (D, G, H) and details (E, F, I) of the mitochondria-ER complexes in mature oocytes. Besides characteristic “necklace-like” complexes formed by variable-sized sacs of ER decorated by several mitochondria (E, F), enlarged tubular aggregates of ER surrounded by only a few mitochondria could be are found also in metaphase II oocytes (G–I). Scale bar, 1 μm (A, B, C, E, F, I) and 5 μm (D, G, H).