de graaf's position in the history of reproduction is unique, summarising the work of anatomists before his time, but unable to benefit from the advances about to be made by microscopy, although he reported its use by antonie van leeuwenhoek in 1673. his personal contributions include the description of testicular tubules, the efferent ducts, and corpora lutea. de graaf may have been the first to understand the reproductive function of the fallopian tube, described the hydrosalpinx, linking its development to female infertility. de graaf also invented a practical syringe, described in his third treatise.