Willem Vrolik, a Dutch anatomist and pathologist who is a pioneer in the field of vertebrate teratology, published teratological works oncyclopia, thepathogenesisof congenital anomalies, and a treatise onconjoined twins as well as Handboek der ziektekundige ontleedkunde (Handbook of pathological anatomy); however, these were later on stopped in production.
Willem Vrolik (29 April 1801  22 December 1863) was a Dutch anatomist and pathologist who was a native of Amsterdam. He was a pioneer in the field of vertebrate teratology. Willem Vrolik published teratological works on cyclopia, the pathogenesis of congenital anomalies, and a treatise on conjoined twins. In the 1840s he published Handboek der ziektekundige ontleedkunde (Handbook of pathological anatomy), as well as Tabulae ad illustrandam embryogenesin hominis et mammalium tam naturalem quam abnormem. 
