Variations of the Circle of Willis at the End of the Human Embryonic Period

Furuichi, Kana; Ishikawa, Aoi; Uwabe, Chigako; Makishima, Hideki; Yamada, Shigehito; Takakuwa, Tetsuya

doi:10.1002/ar.23794

Cited by 10 publications

(7 citation statements)

References 17 publications

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“…The prosencephalon exponentially increases the volume after CS21, which may accelerate the blood supply to the brain. The circle of Willis, which consists of the main arteries supplying blood from the internal carotid arteries and vertebral‐basilar artery to the prosencephalon, is formed at CS21 . As for the region of the external carotid arteries, a subcutaneous capillary plexus is first detected at CS20, spreads upward at CS21, and reaches the vertex of the head at CS23 .…”

Section: Discussionmentioning

confidence: 99%

“…The circle of Willis, which consists of the main arteries supplying blood from the internal carotid arteries and vertebral-basilar artery to the prosencephalon, is formed at CS21. [20][21][22] As for the region of the external carotid arteries, a subcutaneous capillary plexus is first detected at CS20, spreads upward at CS21, and reaches the vertex of the head at CS23. 23 Similar to the development of the subcutaneous capillary plexus, the return of blood flow through the subcutaneous vein should increase.…”

Section: Discussionmentioning

confidence: 99%

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Vesicular swelling in the cervical region with lymph sac formation in human embryos

Ohga

Sakamoto

Yamada

et al. 2019

Congenital Anomalies

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Vesicular swelling in the cervical region (VSC) is occasionally observed among human embryos around Carnegie stage (CS) 21. However, its mechanism and significance in fetal development are unclear. The present study aimed to analyze the relation of development of VSC with jugular lymph sac (JLS) formation. Serial histological sections that were digitalized from 14 embryos at CS20 and CS21 stored at the Kyoto Collection were used for the analysis. Subcutaneous edema and enlargement of the subarachnoid space were found to cause VSC. No obvious abnormalities in cranial regions that may be related to the VSC were detected on histological sections. Three‐dimensional reconstructions revealed the following: (a) the JLS was located bilaterally at the levels between the first and fourth cervical vertebrae; (b) the JLS was pyramidal in shape; and (c) no severe deformity and/or malformation was found in all samples. The JLS was not connected to the subcutaneous tissue and subarachnoid space in all samples. The mean volume of the JLS increased nine‐times from CS20 (0.02 mm3 in VSC [−] group) to CS21 (0.18 mm3 in VSC [−] group). The mean volume of the JLS was comparable between the VSC [−] and VSC (+) groups at both CS20 and CS21. A moderate correlation was observed between VSCd and the mean volume of the JLS in both groups at CS20 (R2 = 0.75) and CS21 (R2 = 0.56). In conclusion, the dynamics of the lymphatic system at the cervical region may contribute to VSC observed around CS21. © 2019 Japanese Teratology Society

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Vesicular swelling in the cervical region with lymph sac formation in human embryos

Ohga

Sakamoto

Yamada

et al. 2019

Congenital Anomalies

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“…Serial transverse sections (10 μm thickness) of whole embryos were digitalized with an Olympus virtual slide system (VS120-S5-J; Olympus Corp., Tokyo, Japan) for histological observations and 3-D reconstructions [ 22 ]. Sequential 2-D images at 25× magnification were digitally cropped around the metanephros.…”

Section: Methodsmentioning

confidence: 99%

Branching morphogenesis of the urinary collecting system in the human embryonic metanephros

et al. 2018

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An elaborate system of ducts collects urine from all nephrons, and this structure is known as the urinary collecting system (UCS). This study focused on how the UCS is formed during human embryogenesis. Fifty human embryos between the Carnegie stage (CS) 14 and CS23 were selected from the Kyoto Collection at the Congenital Anomaly Research Center of Kyoto University, Japan. Metanephroses, including the UCS, were segmented on serial digital virtual histological sections. Three-dimensional images were computationally reconstructed for morphological and quantitative analyses. A CS timeline was plotted. It consisted of the 3-D structural morphogenesis of UCS and quantification of the total amount of end-branching, average and maximum numbers of generations, deviation in the metanephros, differentiation of the urothelial epithelium in the renal pelvis, and timing of the rapid expansion of the renal pelvis. The first UCS branching generation occurred by CS16. The average branching generation reached a maximum of 8.74 ± 1.60 and was already the twelfth in CS23. The total end-branching number squared between the start and the end of the embryonic period. UCS would reach the fifteenth branching generation soon after CS23. The number of nephrons per UCS end-branch was low (0.21 ± 0.14 at CS19, 1.34 ± 0.49 at CS23), indicating that the bifid branching occurred rapidly and that the formation of nephrons followed after. The renal pelvis expanded mainly in CS23, which was earlier than that reported in a previous study. The number of nephrons connected to the UCS in the expanded group (246.0 ± 13.2) was significantly larger than that of the pre-expanded group (130.8 ± 80.1) (P < 0.05). The urothelial epithelium differentiated from the zeroth to the third generations at CS23. Differentiation may have continued up until the tenth generation to allow for renal pelvis expansion. The branching speed was not uniform. There were significantly more branching generations in the polar- than in the interpolar regions (P < 0.05). Branching speed reflects the growth orientation required to form the metanephros. Further study will be necessary to understand the renal pelvis expansion mechanism in CS23. Our CS-based timeline enabled us to map UCS formation and predict functional renal capacity after differentiation and growth.

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“…The collateral cerebral blood flow is mainly dependent on the CoW, especially under ischemic conditions that require compensatory changes in the blood flow [ 38 ]. However, anatomical variations have been reported in the CoW among normal individuals [ 39 ].…”

Section: Discussionmentioning

confidence: 99%

The incomplete circle of Willis is associated with vulnerable intracranial plaque features and acute ischemic stroke

Wang

Shen

Zhao

et al. 2023

Journal of Cardiovascular Magnetic Resonance

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Background The circle of Willis (CoW) plays a significant role in intracranial atherosclerosis (ICAS). This study investigated the relationship between different types of CoW, atherosclerosis plaque features, and acute ischemic stroke (AIS). Methods We investigated 97 participants with AIS or transient ischemic attacks (TIA) underwent pre- and post-contrast 3T vessel wall cardiovascular magnetic resonance within 7 days of the onset of symptoms. The culprit plaque characteristics (including enhancement grade, enhancement ratio, high signal in T1, irregularity of plaque surface, and normalized wall index), and vessel remodeling (including arterial remodeling ratio and positive remodeling) for lesions were evaluated. The anatomic structures of the anterior and the posterior sections of the CoW (A-CoW and P-CoW) were also evaluated. The plaque features were compared among them. The plaque features were also compared between AIS and TIA patients. Finally, univariate and multivariate regression analysis was performed to evaluate the independent risk factors for AIS. Result Patients with incomplete A-CoW showed a higher plaque enhancement ratio (P = 0.002), enhancement grade (P = 0.01), and normalized wall index (NWI) (P = 0.018) compared with the patients with complete A-CoW. A higher proportion of patients with incomplete symptomatic P-CoW demonstrated more culprit plaques with high T1 signals (HT1S) compared with those with complete P-CoW (P = 0.013). Incomplete A-CoW was associated with a higher enhancement grade of the culprit plaques [odds ratio (OR):3.84; 95% CI: 1.36–10.88, P = 0.011], after adjusting for clinical risk factors such as age, sex, smoking, hypertension, hyperlipemia, and diabetes mellitus. Incomplete symptomatic P-CoW was associated with a higher probability of HT1S (OR:3.88; 95% CI: 1.12–13.47, P = 0.033), after adjusting for clinical risk factors such as age, sex, smoking, hypertension, hyperlipemia, and diabetes mellitus. Furthermore, an irregularity of the plaque surface (OR: 6.24; 95% CI: 2.25–17.37, P < 0.001), and incomplete symptomatic P-CoW (OR: 8.03, 95% CI: 2.43–26.55, P = 0.001) were independently associated with AIS. Conclusions This study demonstrated that incomplete A-CoW was associated with enhancement grade of the culprit plaque, and incomplete symptomatic side P-CoW was associated with the presence of HT1S of culprit plaque. Furthermore, an irregularity of plaque surface and incomplete symptomatic side P-CoW were associated with AIS.

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Variations of the Circle of Willis at the End of the Human Embryonic Period

Cited by 10 publications

References 17 publications

Vesicular swelling in the cervical region with lymph sac formation in human embryos

Vesicular swelling in the cervical region with lymph sac formation in human embryos

Branching morphogenesis of the urinary collecting system in the human embryonic metanephros

The incomplete circle of Willis is associated with vulnerable intracranial plaque features and acute ischemic stroke

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