The present invention relates to a method of modulating apoptosis of a granulosa cell. The method includes one or more of the following steps: (i) modulating the concentration and/or activity of BMP-15 and/or BMP-6 that the granulosa cell is exposed to; (ii) modulating activity of a BMP-15 dependent signalling pathway in the granulosa cell; and (iii) modulating activity of a BMP-6 dependent signalling pathway in a granulosa cell.