Gestational sac
From Wikipedia, the free encyclopedia
The gestational sac is the only available intrauterine structure that can be used to determine if an intrauterine pregnancy (IUP) exists, until the embryo is identified. On ultrasound, it is an anechoic (dark) space surrounded by a hyperchoic (white) rim. It is spherical in shape, and usually located in the upper uterine fundus. The mean gestational sac diameter (MGD) is an effective estimate of gestational age between 5 and 6 weeks, with an accuracy of about +/- 5 days. The yolk sac and embryo should be readily identified when the gestational sac reaches a certain size and the yolk sac is 20 mm in size or the fetal pole is 25 mm in size..
 |
This developmental biology article is a stub. You can help Wikipedia by expanding it. |
| Mammalian development of embryo and development of fetus (some dates are approximate - see Carnegie stages) |
|---|
| Week 1: Zygote - Morula - Blastula/Blastomere/Blastosphere - Archenteron/Primitive streak - Blastopore - Allantois - Trophoblast (Cytotrophoblast - Syncytiotrophoblast - Gestational sac)
Week 2: Yolk sac - Vitelline duct - Bilaminar disc Week 3: Hensen's node - Gastrula/Gastrulation - Trilaminar embryo Branchial arch (1st) - Branchial pouch - Meckel's cartilage - Somite/Somitomere - Sclerotome - Myotome - Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm, Splanchnopleure, Somatopleure) Histogenesis and Organogenesis Uterine support: Placenta - Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Amniotic sac (Amnion, Chorion) |
