Biology Reference
In-Depth Information
CHAPTER THIRTEEN
Is Thyroid Hormone Signaling
Relevant for Vertebrate
Embryogenesis?
G. Morvan-Dubois, J.B. Fini, B.A. Demeneix 1
Laboratoire d'Evolution des RĀ“gulations Endocriniennes, MusĀ“um National d'Histoire Naturelle, UMR 7221
CNRS, Department RDDM, Paris, France
1 Corresponding author: e-mail address: demeneix@mnhn.fr
Contents
1.
Introduction
366
2. Both TRs and Deiodinases are Expressed During Embryogenesis
367
2.1 TRs are differentially expressed during embryonic development
367
2.2 Both activating and inactivating deiodinases are present in embryos
370
2.3 Transporters are expressed in embryonic tissues
372
3. Both T 3 and T 4 are Present During Embryonic Stages
373
3.1 T 3 and T 4 are maternally provided in mammals
374
3.2 T 3 and T 4 are present in the egg and early embryo of vertebrates
375
4. What Roles Does TH Signaling Have During Early Development?
377
4.1 Reduced maternal TH levels affect neuromotor development in the child
377
5. Does TH Signaling During Early Development Represent a New Scenario for
Endocrine Disruption?
379
5.1 Epidemiological evidence for the presence of endocrine-disrupting
chemicals during the early development
379
5.2 PBDE effects on TH signaling
380
5.3 The case of TBBPA and its effects on TH signaling
381
6. Conclusion
383
Acknowledgments
387
References
387
Abstract
Classically, thyroid hormones (THs) have been primarily associated with postembryonic
development ( Tata, 1968 ), notably metamorphosis in anuran amphibians and flat fish.
This period is parallel to the perinatal period in man and many marked developmental
transitions in other species. As amply described in other chapters, metamorphosis is
characterized by a peak of thyroxine (T 4 ) and triiodothyronine (T 3 ) that is synchronous
with the metamorphic climax.
In contrast, the developmental period that characterizes embryonic development
prior to the significant production of TH by the endogenous thyroid gland has received
 
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