Abstract Development of fertilizable female gametes involves characteristically nuclear and cytoplasmic transformations during the processes of oocyte growth and meiotic maturation. Present evidence concerning the nature and intra- and extra-oocytic origin of molecules regulating selected aspects of oocyte differentiation are discussed. Particular attention is given to the manner in which specific signals or triggers of oocyte maturation are transduced to change the properties of the oocyte. Data concerning the synthesis and local action of steroid hormones with the amphibian ovary and oocyte are discussed. The effects of secondary cytoplasmic factors, produced in response to steroids, on oocyte growth and maturation as studied in intact and enucleated oocytes are described. The results suggest that the developmental program underlying growth, meiotic arrest, reinitiation of meiosis and subsequent cell division is closely linked to morphological and molecular events occurring in the oocyte membrane and cortex.