4,4-Dimethyl-5 ␣ -cholesta-8,14,24-trien-3  -ol ( I ) from human follicular fluid and 4,4-dimethyl-5 ␣ -cholesta-8,24-dien-3  -ol ( II ) from bull testes have been reported to activate meiosis in mouse oocytes (Byskov et al., 1995. Nature. 374: 559-562). Described herein are new chemical syntheses of I, II , and the ⌬ 8(14),24 analog XXII . A critical step in these syntheses was a remarkably high yield side chain oxidation of 3  -acetoxy-4,4-dimethyl-5 ␣ -cholest-8(14)-en-15one to the corresponding C 24 24-hydroxy compound VI . Oxidation of VI to the aldehyde, followed by Wittig olefination gave 3  -acetoxy-4,4-dimethyl-5 ␣ -cholesta-8(14),24dien-15-one. Reduction with sodium borohydride to the 15  -hydroxysteryl ester, dehydration with sulfuric acid in CHCl 3 , and saponification furnished I in high purity. Reduction of VI with sodium borohydride to the 15-hydroxysteroid followed by dehydration gave 3  -acetoxy-4,4-dimethyl-5 ␣ -chola-8,14-dien-24-ol. Hydrogenation over Raney nickel gave the monounsaturated ⌬ 8(14) and ⌬ 8 compounds.Oxidation to the corresponding aldehydes followed by Wittig olefination and saponification gave II and XXII . Chromatographic, mass spectral, and 1 H and 13 C nuclear magnetic resonance spectral data have been presented for the synthetic sterols and their derivatives. I, II, XXII , and their ⌬ 8,14 and ⌬ 7,14 analogs, at 3 g per ml, caused a resumption of meiosis in mouse oocytes in the presence of hypoxanthine (3.5 m m ). Under the same conditions, ⌬ 5 and ⌬ 5,7 sterols were inactive. -