The development of the thyroid glands in anuran amphibians of Iraq


  • *This work was carried out during the stay of the first author at Mosul University, Iraq.


The development of the thyroid gland was studied in various larval and metamorphic stages of three Iraqi anurans of the genera Bufo, Hyla and Rana. At comparable stages of development, differentiation of the gland occurs earlier in the last two genera than in Bufo. It is suggested that the development of the thyroid during prometamorphosis is closely related to the histogenesis of the pronephric system in these genera.