Pyramidal lobe of the thyroid gland and the thyroglossal duct remnant: A study using human fetal sections

Takanashi, Yoshitaka; Honkura, Yohei; Rodríguez‐Vázquez, José Francisco; Murakami, Gen; Kawase, Tetsuaki; Katori, Yukio

doi:10.1016/j.aanat.2014.09.001

Cited by 14 publications

(21 citation statements)

References 12 publications

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“…The presence of analogous ectopic thyroid tissue has been described in humans; a pyramidal lobe of the thyroid is a common variation of human thyroid anatomy, estimated to occur in approximately 40% of individuals 62, 63 , and the ectopic thyroid tissue observed in our study bears a striking resemblance to the pyramidal lobe tissue observed in human embryos 64 . Additionally, lingual thyroid 65 , is a known congenital anomaly present in up to 10% of the population 66 .…”

Section: Discussionsupporting

confidence: 81%

Elevated levels of Wnt signaling disrupt thymus morphogenesis and function

Swann

Happe

Boehm

2017

Sci Rep

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All vertebrates possess a thymus, whose epithelial microenvironment is essential for T cell development and maturation. Despite the importance of the thymus for cellular immune defense, many questions surrounding its morphogenesis remain unanswered. Here, we demonstrate that, in contrast to the situation in many other epithelial cell types, differentiation of thymic epithelial cells (TECs) proceeds normally in the absence of canonical Wnt signaling and the classical adhesion molecule E-cadherin. By contrast, TEC-intrinsic activation of β-catenin-dependent Wnt signaling blocks the morphogenesis of the thymus, and overexpression of a secreted Wnt ligand by TECs dominantly modifies the morphogenesis not only of the thymus, but also of the parathyroid and thyroid. These observations indicate that Wnt signaling activity in the thymus needs to be precisely controlled to support normal TEC differentiation, and suggest possible mechanisms underlying anatomical variations of the thymus, parathyroid and thyroid in humans.

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Section: Discussionsupporting

confidence: 81%

Elevated levels of Wnt signaling disrupt thymus morphogenesis and function

Swann

Happe

Boehm

2017

Sci Rep

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“…The aortic arch (or the DA) originates from the 4 th (or 6 th ) pharyngeal arch artery. According to our studies on the pharyngeal arch structures [1,6,7,13], the initial vertebral levels of these arteries almost correspond to the second-third vertebral bodies. At the site, the larynx, parathyroid and thymus together develop from the pharyngeal pouches.…”

Section: Introductionmentioning

confidence: 76%

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sagittal sections

et al. 2019

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Background: At birth, the ductus arteriosus (DA) merges with the aortic arch in the slightly caudal side of the origin of the left subclavian artery (SCA). Since the SCAs (7 th segmental arteries) were fixed on the level of the 7 th cervical-first thoracic vertebral bodies, the confluence of DA should migrate caudally. We aimed to describe timing and sequence of the topographical change using serial sagittal sections of 36 human embryos and foetuses (CRL 8-64 mm; 5-10 weeks), Those made easy evaluation of the vertebral levels possible in a few section. Materials and methods: The DA or 6 th pharyngeal arch artery seemed to slide down in front of the sympathetic nerve trunk along 1.0-1.2 mm from the second cervical vertebral level at 5-6 weeks and, at 6 weeks (CRL 14-17 mm), the DA confluence with aorta reached the 7 th cervical level. Because of the highly elongated common carotid artery, the sliding of DA confluence seemed to be much shorter than the cervical vertebrae growing from 1 mm to 2.4 mm. Results: At the final topographical change at 6-7 weeks, the DA confluence further descended to a site 1-vertebral length below the left SCA origin. From 6 to 9 weeks, a distance from the top of the aortic arch to the left SCA origin was almost stable: 0.3-0.5 mm at 6 weeks and 0.4-0.6 mm at 9 weeks. Conclusions: The heart descent and the caudal extension of the trachea and bronchi, those occurred before the DA sliding, were likely to be a major driving force for the sliding. (Folia Morphol 2019; 78, 4: 720-728)

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“…Notably, at this late phase, the laterally-located thymus further descended to face the pericardium, in contrast to the medially-located thyroid and parathyroid, which maintained their higher positions. The thyroid was still fixed by the thyroglossal duct, while the parathyroid was likely to connect to the thyroid at an early stage [11]. The final descent of the heart to the lower thoracic level seemed to occur due to growth of the ventricles.…”

Section: Discussionmentioning

confidence: 99%

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sections

Abé

Yamamoto

Suzuki

et al. 2017

Okajimas Folia Anat. Jpn.

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Summary: At birth, the ductus arteriosus (DA) merges with the aortic arch in the caudal side of the origin of the left subclavian artery (ltSCA). Since the SCA (seventh segmental arteries) were fixed on the levels of the seventh cervical-first thoracic vertebral bodies, the confluence of the DA should migrate caudally toward the lower level. We aimed to describe the changing topographical anatomy of the DA and SCA using serial sections. First, we examined serial sagittal sections of 11 embryos (Carnegie stage 15−18), but the specimens were clearly divided into 2 groups with and without the lower confluence of the DA. Next, we examined serial horizontal sections of 40 specimens (Carnegie stage 14−16) and we chose 5 specimens (CRL 11 mm, 3 specimen; 1, 14 mm; 1, 15 mm) including the DA near (within 1-vertebral segment from) the ltSCA. The final approach of the DA occurred during the heart descent in which the apex of the heart migrated from the level of the first to the fourth thoracic vertebral body. Thus, the DA reached the SCA level before establishment of the heart descent. The right aortic arch maintained its entire course in 2 of the 5 specimens. Therefore, the positioning of the DA along the left aortic arch might occur independently of degeneration of the right arch. Notably, the tracheal bifurcation level was higher when the DA-ltSCA distance was greater. A contribution of the increased pulmonary volume was suggested for the final approach of the DA.

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Pyramidal lobe of the thyroid gland and the thyroglossal duct remnant: A study using human fetal sections

Cited by 14 publications

References 12 publications

Elevated levels of Wnt signaling disrupt thymus morphogenesis and function

Elevated levels of Wnt signaling disrupt thymus morphogenesis and function

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sagittal sections

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sections

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