Follicular growth is described as a continuum. It goes on at all times, at all ages, uninterrupted by pregnancy or other periods of non-ovulation. A distinction is made between the continuum at the beginning of follicular growth and events concerning the cyclicity at the end of follicular growth, i.e. ovulation. Follicles grow sequentially. Also large follicles continue to grow until they become atretic or ovulate. No evidence for a pool of large follicles held in reserve could be found. Examination of the effect of PMSG on the growth of large follicles showed that this hormone provented the degeneration of large follicles, thus allowing more follicles to grow further. As in the mouse, follicular growth occurs during human infancy and is the normal event during childhood. Ovaries without signs of follicular growth are uncommin in the child and are apparently connected with certain systemic diseases.