Eukaryotic Histones are basic and water soluble nuclear proteins that form hetero-octameric nucleosome particles by wrapping 146 base pairs of DNA in a left-handed super-helical turn sequentially to form chromosomal fibers. Two molecules of each of the four core Histones (Histone H2A, H2B, H3, and H4) form the octamer, which consists of two H2A-H2B dimers and two H3-H4 dimers that are nearly symmetrical by tertiary structure. Over 80% of nucleosomes contain the linker Histone H1, derived from an intronless gene, that interacts with linker DNA between nucleosomes and mediates compaction into higher order chromatin. H1FOO (H1 histone family, member O, oocyte-specific), also known as OSH1, is a 346 amino acid oocyte-specific Histone that localizes to both the nucleus and the cytoplasm. Expressed as multiple alternatively spliced isoforms, H1FOO is thought to play an important role in gene control during oogenesis and early embryogenesis and is crucial for meiotic maturation of germinal vesicle-stage oocytes.