Human Growth and Development / Unit 9 HGD 1220 worked example, 60 to 90 seconds
Primary and Secondary Sex Characteristics
The idea
Primary sex characteristics are directly involved in reproduction: the ovaries and uterus, and the testes and penis. Menarche is the first menstrual period. Spermarche, also called semenarche, is the first ejaculation, often a nocturnal emission. Secondary sex characteristics are not directly reproductive: breast development, called thelarche; pubic and underarm hair, called pubarche; and facial hair and a deeper voice in males.
In practice
A girl's breast development beginning well before her first period, and a boy's testicular growth beginning well before his voice deepens.
Where people slip
In girls, ovarian and breast growth come early; in boys, testicular growth comes first, and spermarche arrives mid-puberty rather than at its start. Pubic hair growth is pubarche; adrenarche is the earlier rise in adrenal hormones, from about six to eight. Exam items ask which characteristics are primary: only those directly involved in reproduction.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
Something wrong in this lesson? Flag it · Sources for Human Growth and Development