What are primary and secondary sexual characteristics?

Primary sexual characteristics are the reproductive organs present at birth (e.g. ovaries/uterus, testes/penis) that directly enable reproduction.

Secondary sexual characteristics are the features that develop at puberty under sex hormones - e.g. breast development, pubic/axillary hair, the menstrual cycle (girls), and voice deepening, facial hair, muscle growth (boys).

Clinical relevance. Distinguishing primary (birth) from secondary (pubertal) sexual characteristics frames the assessment of normal and abnormal puberty.

More Detail

Primary and secondary sexual characteristics

These distinguish the reproductive organs from the pubertal features.

Primary sexual characteristics

• The reproductive organs present from birth - e.g. ovaries, uterus, and vagina (female); testes and penis (male) - directly involved in reproduction.

Secondary sexual characteristics

• Features that develop at puberty under the influence of sex hormones (oestrogen, testosterone).
• Female - breast development, pubic and axillary hair, widening of the hips, and onset of menstruation.
• Male - deepening of the voice, facial/body hair, increased muscle mass, and growth of the genitalia.

Significance

• The development and timing of secondary sexual characteristics reflect normal pubertal progression - their absence, delay, or early onset can indicate an endocrine problem.