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

Abstract

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)

Early Appearance of Epicardial Adipose Tissue through Human Development

“…We studied 41 embryos from 32 GD (5–7 mm, CS 14) to 8 GW (two months) (30 mm, CS 23) [ 29 ] at the end of the embryonic period and the onset of fetal life ( Table 1 ), and 23 fetuses from 9 GW until full term, i.e., 36 GW (320 mm CRL), as shown in Table 2 . This collection of embryos and fetuses has been studied in numerous doctoral theses and research woks on heart development and other structures (see [ 30 , 31 , 32 ], among others). From the large collection of specimens, we selected normal specimens without cardiac malformations.…”

Cavitation processes in a space filled with loose mesenchymal tissues: a comparison between the retrosternal space and the middle ear tympanic cavity in human fetuses

“…This study was approved by the Ethics Committee of Complutense University (B08/374). Development of the sternum in early fetuses [13] and sagittal section morphology of the thoracic region [8,9] are previously reported. Most images of histology were taken with a Nikon Eclipse 80, whereas photographs at ultra-low magnification (objective lens <1x) were obtained using a high-grade flat scanner with translucent illumination (Epson scanner GTX970).…”

Lung fusion with the liver in chick and quail embryos

“…We considered that a stable topographical relation between the lung and liver was required for the fusion. In human embryos at 5 weeks, a drastic change in the height of a confluence or terminal of the ductus arteriosus occurs in human embryos (Jin et al, 2019). When the descent of the heart was slightly delayed, the lung and liver were likely to attach tightly.…”