For girls, the observable changes of puberty usually begin with nipple growth. Soon a few pubic hairs are visible, then peak growth spurt, widening of the hips, the first menstrual period (menarche), full pubic-hair pattern, and breast maturation. For boys, the usual sequence is growth of the testes, initial pubic-hair growth, growth of the penis, first ejaculation of seminal fluid, appearance of facial hair, peak growth spurt, deepening of the voice, and final pubic-hair growth.