The Sages created a metaphor for [the developmental stages of] a woman: a green fig, a small fig, and tzemel.  [At the stage when she is likened to] “a green fig,” she is still a child. [The stage of] “a small fig” [alludes to] the days of her naarus [period]. During [both] this [stage] and that [stage], her father is entitled to her finds and to her earnings and to the annul-ment of her vows. “Tzemel” [alludes to a stage of full adulthood;] once she reaches full adulthood, her father no longer has authority over her.

What are her signs?  R’ Yose HaGlili says: From when a crease forms under the breast.  R’ Akiva says: From when the breasts hang down.  Ben Azzai says: From when the areola darkens.  R’ Yose says: [From when the breast is large] enough that one shall put his hand on the nipple and it sinks in and delays returning [to its original position].

[In the case of a] 20-year-old [female] who has not brought two [pubic] hairs —- she shall bring proof that she is 20 years old, and she [must also exhibit the signs of] an aylonis, [and then,] she neither performs chalitzah nor is taken as a yibum wife.  [In the case of a] 20-year-old [male] who has not produced two [pubic] hairs —- he shall bring proof that he is 20 years old, and he [must also exhibit the signs of] a saris, [and then,] he neither performs chalitzah nor takes [his brother’s widow as] a yibum-wife; these are the words of Beis Hillel.  Beis Shammai say: [The aforementioned rulings apply to] this [female] and that [male when they are] 18 years old.  R’ Eliezer says: [The law of] the male accords with the opinion of Beis Hillel, and [the law of] the female accords with the opinion of Beis Shammai, for the woman hastens to come [to physical maturity] before the man.

[When] the lower sign comes before the upper [sign] comes, [a girl] performs either chalitzah or yibum. [When] the upper [sign] comes before the lower [sign] comes —- even though this is not possible —- R’ Meir says: She performs neither chalitzah nor yibum. But the Sages say: She performs either chalitzah or yibum, because they have said: It is possible for the lower [sign] to come before the upper [sign] has come, but it is not possible for the upper [sign] to come before the lower [sign] has come.