Morphology and histogenesis of human fetal thyroid gland

Introduction: About 5% of the world population is affected from various thyroid disorders. The present study is undertaken to describe the morphological and morphometric variations in the fetal thyroid glands of thyroid at different stages of development in the intrauterine life. Methodology: Forty medically terminated fetuses of both sexes ranging from 15 to 36 weeks of gestation were included. The external parameters recorded were: Fetal weight; crown-rump length; foot Length; Location; Presence/absence of isthmus; Presence of pyramidal lobe; Presence of an accessory thyroid tissue were observed in situ. The length, width, and thickness of each lobe and the isthmus were noted. Results: The specimens were categorized into three gestational groups, i.e., 10–20 weeks, 21–30 weeks, and 31–40 weeks. The statistical analysis suggests that there is significant increase in fetal thyroid weight, lengths and widths of the right and left lobes, and length of the isthmus with increase in gestational age. There was no significant increase in width of isthmus with gestational age. There was no significant difference in all thyroid parameters by gender. Conclusion: The data regarding the various parameters collected and analyzed in the present study emphasized the significance of an insight into the morphological variations, morphometric dimensions, and histological findings of foetal thyroid glands in diagnosing various diseases.