Luteinising hormone (LH) stimulates the Leydig cells of the testes to produce testosterone but does not have a significant effect on the ovary until after ovulation first occurs. In contrast, follicle-stimulating hormone (FSH) stimulates ovarian oestrogen production in the female, but has little effect on the testes in males until the time of puberty, when seminiferous tubules enlarge under FSH stimulation and cause enlargement of the size of the testes.
