Body-stalk

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Body-stalk

Diagram showing the expansion of amnion and delimitation of the umbilicus.

Section through the embryo.
Gray's	subject #10 53
Dorlands/Elsevier	s_21/12755040

The caudal end of the embryo is at first connected to the chorion by a band of mesoderm called the body-stalk, but with the formation of the caudal fold the body-stalk assumes a ventral position; a diverticulum of the yolk-sac extends into the tail fold and is termed the hind-gut.

The function of the body-stalk is later replaced by the umbilical cord.

Additional images

Gray17.png

Human embryo—length, 2 mm. Dorsal view, with the amnion laid open. X 30.
Human embryo of 2.6 mm.
Diagram showing later stage of allantoic development with commencing constriction of the yolk-sac.
Model of human embryo 1.3 mm. long.
Section through ovum imbedded in the uterine decidua.
Embryo between eighteen and twenty-one days.
Human embryo about fifteen days old. Brain and heart represented from right side. Digestive tube and yolk sac in median section.

External links

Swiss embryology (from UL, UB, and UF) hdisqueembry/triderm0

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v • d • e Developmental biology > Human embryogenesis (development of embryo) and development of fetus (some dates are approximate - see Carnegie stages and a timeline)
Week 1	Fertilization - Egg activation - Zygote - Cleavage - Morula - Blastula (Blastomere) - Blastocyst - Inner cell mass
Week 2	Bilaminar disc (Hypoblast, Epiblast)
Week 3 (Trilaminar embryo, germ layers)	Archenteron/Primitive streak (Primitive pit, Primitive knot/Blastopore, Primitive groove) - Gastrula/Gastrulation - Regional specification Ectoderm: Surface ectoderm - Neuroectoderm - Somatopleure - Neurulation - Neural crest Endoderm: Splanchnopleure Mesoderm: Chorda- - Paraxial (Somite/Somitomere/Sclerotome/Myotome/Dermatome) - Intermediate - Lateral plate (Intraembryonic coelom, Splanchnopleure/Somatopleure)
Extraembryonic/uterus	Trophoblast (Cytotrophoblast, Syncytiotrophoblast) Blastocoele - Yolk sack/exocoelomic cavity - Heuser's membrane - Extraembryonic coelom - Vitelline duct Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Allantois Placenta - Decidua (Decidual cells) - Chorionic villi/Intervillous space - Gestational sac (Amnion/Amniotic sac/Amniotic cavity, Chorion)
Histogenesis	Programmed cell death - Stem cells - Germ line development
Organogenesis	Limb development: Limb bud - Apical ectodermal ridge/AER other structures: Eye development - Cutaneous structure development - Heart development - Development of the urinary and reproductive organs