Figure 1
From: Dual roles for ubiquitination in the processing of sperm organelles after fertilization
Fertilization in C. elegans. Oocytes are arrested in prophase of meiosis I. Fertilization occurs in the spermatheca of the adult hermaphrodite. A single, mature spermatozoon fuses with the oocyte. After fusion, the maternal genome completes meiosis I resulting in the formation of the first polar body. Meiosis II ensues immediately and leads to the formation of the second polar body. During this time, the sperm DNA remains in a highly condensed state. The sperm organelles stay closely associated with the sperm DNA. Immediately following the completion of meiosis II, the sperm DNA decondenses and the maternal and paternal pronuclei are formed. The maternal pronucleus migrates to the sperm pronucleus and upon joining, the first mitotic cell division commences. This entire process occurs within the first half hour after fertilization. DNA is shown in blue, MOs are green, and mitochondria are red.