April - June 2006, Volume 2, Issue 2

Busuioc C, Raducanu-Lichiardopol C, Bold A, Mogoanta L, Georgescu C

Immunohistochemical aspects of the human foetal thyroid

Acta Endo (Buc) 2006, 2 (2): 139-150
doi: 10.4183/aeb.2006.139

Objective: Thyroid development was studied mainly on animal models and data in humans are scarce. Knowing that there are interspecies differences and a specific timing of thyroid development we aimed to reveal intimate aspects of the human foetal morphology and function.\r\nMaterial and method: Thyroids from 20 aborted fetuses of different gestational ages (8-16 weeks) were embedded in paraffin, sectioned, coloured and immunohistochemically processed using the Avidin-Biotin Complex–Peroxidase (ABC) method with a pannel of antibodies aimed to reveal the secretory activity (antithyroglobulin monoclonal and polyclonal and anti TITF1 antibodies), the differentiation of intermediate filaments (anti AE1/AE3, anti CK7 and antivimentin monoclonal antibodies), of C cells (anti CEA monoclonal antibodies) and of the thyroid vascular net (anti CD34 monoclonal antibodies).\r\nResults: Thyroglobulin expression was present in thyrocytes cytoplasm even before follicles are formed (8-10 weeks); after 12 weeks appeared also within the colloid and expression increased after 14 weeks showing a luminal pattern of distribution similar to the mature thyroid. TITF1 was present in the thyrocytes nuclei of all groups, weak till 14 weeks and intense thereafter and in the C cells nuclei. C cells appeared after 10 weeks and expressed CEA, vimentin and CK7. Immunostaining for keratins (AE1/AE3, CK7) was rarely positive in cordonal thyrocytes, but was present in follicular thyrocytes and increased with gestational age. Some thyrocytes of all groups were vimentin positive and showed coexpression with cytokeratins. CD 34 expression indicated an early vascular differentiation being present in isolated endothelial cells before 10 weeks and structured capillaries after 10 weeks of gestational age.\r\nConclusions: Immunohistochemistry proved to be a useful tool in our attempt to shed light on human thyroid development which would permit a better pathogenic understanding of thyroid dysgenesias and thyroid neoplasms.

Keywords: thyroid, foetal, immunohistochemistry, TITF1, AE1/AE3, CD34, CEA, vimentin, CK7

Correspondence: Cristina Busuioc, MD, Ph D, Departments of Histology, Universty of Medicine and Pharmacy, Craiova, Romania, e-mail: pan_med_ro@yahoo.com