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Embryology, Anatomy, and Physiology of the Bladder
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Allan Johnston, Tarik Amer, Omar Aboumarzouk, Hashim Hashim
The cloaca is the terminal portion of the embryonic hindgut:Lined with endoderm.Forms a pit in contact with the embryonic surface ectoderm (proctodeum/anal pit).Receives the allantois ventrally.Divided into a dorsal and ventral part by the urorectal septum (Figure 10.1).
Placenta Throughout Gestation
Published in Mary C. Peavey, Sarah K. Dotters-Katz, Ultrasound of Mouse Fetal Development and Human Correlates, 2021
Mary C. Peavey, Sarah K. Dotters-Katz
In the mouse, there are initially three vessels (one artery and two veins) in the vitelline portion of the umbilical cord, which is closest to the placenta. However, at the fetal or allantoic portion, the umbilical cord contains one artery and one vein. Thus, most color Doppler of the umbilical cord in the mouse fetus has two vessels. The umbilical artery and the umbilical vein form at 9.5 dpc and are subsequently easy to identify on ultrasound.
The placenta and the umbilical cord
Published in Frank J. Dye, Human Life Before Birth, 2019
The surface of the umbilical cord is covered by a layer of amnion, which gives it a shiny appearance. Included within this outer layer is the long, attenuated yolk stalk. At the end of the yolk stalk at the level of the placenta is found the diminutive yolk sac (Figure 10.6A). A cross-section through the umbilical cord reveals the two smaller arterial cross-sections and the somewhat larger cross-section of the umbilical vein. In addition, the very tiny yolk stalk cross-section is present as well as that of the allantois (one of the four extraembryonic membranes). Although in humans the allantois is not the well-developed structure it is in the development of other mammals, its blood vessels become the umbilical blood vessels. Beneath the surface layer of amnion is found a special kind of connective tissue, Wharton's jelly, within which are embedded all the structures just mentioned in considering the cross-section of the cord (see Figure 10.6B).
Comparative study of umbilical cord cross-sectional area in foetuses with isolated single umbilical artery and normal umbilical artery
Published in Journal of Obstetrics and Gynaecology, 2022
Tian-Gang Li, Chong-Li Guan, Jian Wang, Mei-Juan Peng
UAs are the main vascular channels connecting the foetus and the placenta. The umbilical circulation provides the foetus with nutrients and gas exchange; therefore, haemodynamic changes in the umbilical cord suggest an intrauterine oxygen supply and placental pathological changes. The embryonic umbilical cord surrounds the allantois; thus, two of the allantoic arteries form the UA. If one of the UAs shrinks, an SUA is formed. Formerly, foetal umbilical blood flow was assessed mainly for pregnancy-induced hypertension and intrauterine hypoxia. The lack of a UA in isolated SUA may cause foetal UA haemodynamic changes and affect foetal intrauterine development (Battarbee et al. 2017). Monitoring the umbilical blood flow in foetuses with isolated SUA and the general condition of umbilical blood vessels may aid in early detection of the haemodynamic changes associated with isolated SUAs.
The Allantois and Urachus: Histological Study Using Human Embryo and Fetuses
Published in Fetal and Pediatric Pathology, 2022
Xuelai Liu, Xianghui Xie, Zhe-Wu Jin, Huan Wang, Yanbiao Song, Peng Zhao, Long Li
In conclusion, the allantois is a temporary organ in human embryos and fetuses. During development, the urinary bladder develops with shrinkage of the allantois, with the urachus forming from the distal end and the urogenital sinus forming from the proximal end of the allantois. The urachus develops into a closed fibrous cord in the extra-peritoneal space and is located between the base of the urinary bladder and the umbilicus after birth.