Final answer:
The presence of breast buds indicates a girl has entered Tanner stage II of puberty, which typically starts around age 10 and is completed by about age 14. This stage includes the initial development of breast tissue and pubic hair.
Step-by-step explanation:
The presence of breast buds corresponds to Tanner stage II of puberty in females. The Tanner stages are a scale reflecting physical development in children, adolescents, and adults. Changes in these traits are traditionally divided into five stages. Tanner stage I is the child stage before the onset of puberty, while Tanner stage V is the adult stage at the end of puberty. The development of breast buds and pubic hair begins around age 10 and is typically completed by about age 14. This stage of puberty occasions a visible transformation in the growth and development of the breasts and reflects the overall biological and physical developments occurring during this time.
During normal hormonal fluctuations in the menstrual cycle, the breast tissue responds to changing levels of estrogen and progesterone which may cause swelling and tenderness, especially during the secretory phase. Further development and enlargement of the breasts occur if pregnancy ensues, in response to the increase in hormones leading to further development of the mammary tissue.