<prompt> Period of adolescent growth in boys is:3 years3.5 years4 years5 years  <response>: Key Concept:The stages of sexual development in boys are more difficult to specifically define than in girls. Puberty begins later and extends over a longer period-about 5 years compared with 3 12 years for girls.Adolescent Growth Stages Versus Secondary Sexual Characteristics:Girls:Total Duration of Adolescent Growth: 3 12 years Stage 1 Beginning of adolescent growth Appearance of breast buds, initial pubic hair.Stage 2 About 12 months laterPeak velocity in height Noticeable breast development, axillary hair, darker and more abundant pubic hair.Stage 3 12-18 months laterGrowth spurt endingMenses, broadening of hips with adult fat distribution, breasts completed.Boys:Total Duration of Adolescent Growth: 5 yearsStage 1 Beginning of adolescent growthFat spurt weight gain, feminine fat distribution.Stage 2 About 12 months laterHeight spurt beginning Redistribution and reduction in fat, pubic hair, growth of penis.Stage 3 8-12 months laterPeak velocity in height Facial hair appears on upper lip only, axillary hair, muscular growth with harder, more angular body form.Stage 4 15-24 months laterGrowth spurt ending Facial hair on chin and lip, adult distribution and color of public and axillary hair, adult body form.Ref: Contemporary orthodontics Proffit 6th ed page 150 