One example of a woman who, according to the baraita, will not receive a payment if she is seduced or raped, is an ailonit – a sexually underdeveloped woman whose physical makeup will not allow her to have children (the term stems from the word ayil – a male ram – alluding to her lack of femininity).
From the detailed discussions in the Gemara – mainly in Massekhet Yevamot – it appears that an ailonit suffers from a genetic defect that does not allow her to have children, as distinct from an akarah – a barren woman – whose physical and sexual development is ordinarily normal, but cannot have children because of some other deficiency or impediment. From those descriptions it appears that an ailonit can be recognized by certain unique physical traits, including a lack of secondary sex characteristics, like pubic hairs. Furthermore, it appears from the Gemara that there are different types of ailonit, ranging from women who have an overabundance of male hormones to those who suffer from Turner syndrome, where only one X chromosome is present and fully functioning. Approximately 98% of all fetuses with Turner syndrome spontaneously abort; the incidence of Turner syndrome in live female births is believed to be about 1 in 2500.
Within Jewish law there are many discussions about the status of an ailonit, mainly because of the lack of secondary female sex characteristics and because they develop at a relatively advanced age. Thus we find questions about when an ailonit is considered to have reached the age of adulthood, which halakha ordinarily defines as physical maturity.
With regard to the question of the monetary payment in a case of seduction or rape, our Gemara explains that the reason the baraita suggests that an ailonit does not receive payment is because she is perceived to be a ketana – a minor – according to Rabbi Meir. The hakhamim, who disagree with him and rule that a ketana receives these payments, would rule that an ailonit does, as well.