prothyrocyte

The story

1. Proto-Indo-European*per-der.?
2. Proto-Indo-European*pér
3. Proto-Indo-European*pró
4. Ancient Greekπρό (pró)
5. Englishpro-
6. Proto-Indo-European*dʰwer-
7. Proto-Hellenic*tʰurā
8. Ancient Greekθῠ́ρᾱ (thŭ́rā)
9. Ancient Greekθῠρεός (thŭreós)
10. Proto-Indo-European*weyd-
11. Proto-Indo-European*wéydos
12. Proto-Hellenic*wéidos
13. Ancient Greekεἶδος (eîdos)
14. Ancient Greekθῠρεοειδής (thŭreoeidḗs)
15. New Latinthyreoīdēs
16. Englishthyroid
17. Englishthyro-
18. Ancient Greekκῠ́τος (kŭ́tos)
19. Latincyta
20. Englishthyrocyte
21. English todayprothyrocyte

From pro- + thyrocyte.