Question

The presence of breast buds and the development of breast tissue occur at a specific time during gestation and are reliable indicators of gestational age, as is the development of genitalia, which also occurs at a specific time during gestation?

Answer 1

While breast bud development is not a definitive gestational age marker, genitalia development between weeks 9 to 15 is, allowing for nearly 100% accurate sex determination through ultrasound. The testes in males start in the abdomen and descend later.

Step-by-step explanation:

The presence of breast buds and the development of breast tissue in the fetus are not specifically reliable indicators of gestational age, as they do not occur at a clearly defined time during gestation. However, the development of genitalia is a more precise marker. Between weeks 9 to 15 of gestation, the fetus undergoes rapid development of reproductive organs. By week 12, the external genitals of male and female fetuses can be clearly differentiated, and the biological sex of the fetus can be determined with nearly 100 percent accuracy through an obstetric ultrasound.

Regarding the development of the gonads, both male and female fetuses initially have biopotential gonads that can develop into either male or female sexual organs. For male fetuses, the testes are initially located inside the abdomen and only descend into the scrotum later in gestation, usually by the 26th to 28th week. Before week 9, the genitalia of both sexes appear similar and only after this period does sexual differentiation occur.