The Kyoto Collection of Human Embryos and Fetuses: History and Recent Advancements in Modern Methods.

The Kyoto Collection of Human Embryos and Fetuses, the largest collection of human embryos worldwide, was initiated in the 1960s, and the Congenital Anomaly Research Center of Kyoto University was established in 1975 for long-term storage of the collection and for the promotion of research into human embryonic and fetal development. Currently, the Kyoto Collection comprises approximately 45,000 specimens of human embryonic or fetal development and is renowned for the following unique characteristics: (1) the collection is considered to represent the total population of fetal specimens nationwide in Japan, (2) it comprises a large number of specimens with a variety of external malformations, and (3) for most specimens there are clinical and epidemiological data from the mothers and the pregnancies concerned. Therefore, the specimens have been used extensively for morphological studies and could potentially be used for epidemiological analysis. Recently, several new approaches such as DNA extraction from formalin-fixed specimens or geometric morphometrics have been adopted and it is to be expected that further technological advances will facilitate new studies on the specimens of the Kyoto Collection as well as of other human embryo collections worldwide. Permanent preservation of the Kyoto Collection is, therefore, of paramount importance so that it will continue to contribute to human embryological studies in the future.