WS-1 Harmonization of terminology and classification in reproductive and developmental toxicology in experimental animals 1. Categorization into malformations or variations for skeletal findings in fetuses in reproductive and developmental toxicity studies What structures cannot be observed/identified in fetal skeletal specimens?

摘要

The Terminology Committee of the Japanese Teratology Society (JTS) recommended classification of external and visceral findings in fetuses under 3 categories of "Malformation", "Variation" or "Not categorized" in the Workshop of the 55th Annual Meeting of the JTS in 2015. In this Workshop in 2016, classification of the skeletal findings will be discussed. A survey for classification of fetal skeletal findings using harmonized terminology (Version 2) was conducted in Japan, and responses were received from 18 facilities and one authority. Among 18 facilities, 11 were pharmaceutical companies, five were companies handling medical and agricultural chemicals, one was a company handling agricultural chemicals, and one was listed as other facility. The number of skeletal findings listed in the Version 2 Terminology is approximately 1000, because detailed observation can be conducted based on about 50 years of experience in evaluating these findings, covering about 70 regions in the body. Among the findings listed, there are those that are less clear in their descriptions to other ones that cannot be easily observed or identified in fetal specimens. In this Workshop, we will propose to classify 11 skeletal structures into "Not categorized". Auditory ossicles, Ethmoid, Meckel's cartilage, Presphenoid, and Vomer cannot be easily observed. Lacrimal, Carpal bone, Patella, and Tarsal bone generally cannot be identified even in double-stained specimens. With regards to "Suture" and "Intersternebral cartilage", other terms may be used to better describe these findings.