Theiler Stage

Theiler stages (TS) define mouse development by a set of morphological criteria ([Theiler, 1989](https://doi.org/10.1007/978-3-642-88418-4)). This staging scheme is used because embryos at the same gestational age can have developed at different rates and therefore exhibit different morphological characteristics. Theiler stages may in some cases correspond to a single gestation age, but more often cover a range of ages. (from [https://www.informatics.jax.org/glossary/theiler](https://www.informatics.jax.org/glossary/theiler))