Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/20 02:26:05」(JST)

wiki en

The gestational sac is the large cavity of fluid surrounding the embryo. During early embryogenesis it consists of the extra-embryonic coelom, also called the chorionic cavity. By approximately 9 weeks of gestational age the amniotic sac has expanded to occupy the majority of its volume, eventually filling the entire space. The gestational sac is usually contained with the uterus. It is the only available structure that can be used to determine if an intrauterine pregnancy exists until the embryo is identified.

On obstetric ultrasound, the gestational sac is a dark ("anechoic") space surrounded by a white ("hyperchoic") rim.

Structure

The gestational sac is spherical in shape, and usually located in the upper part of the fundus of the uterus. By approximately 9 weeks of gestational age, the amniotic sac has expanded to occupy the majority of the volume of the gestational sac, eventually expanding to reduce the extraembryonic coelom to a thin layer between the amnion membrane and the mesoderm. By then, the gestational sac is usually simply called the "amniotic sac".

Development

The extraembryonic coelom (or chorionic cavity) that constitutes the gestational sac for most part of the embryogenesis is a portion of the conceptus consisting of a cavity between Heuser's membrane and the Trophoblast.

During formation of the primitive yolk sac, some of the migrating hypoblast cells differentiate into mesenchymal cells that fill the space between Heuser's membrane and the Trophoblast, forming the extraembryonic mesoderm. As development progresses, small lacunae begin to form within the extraembryonic mesoderm which become larger and form the extraembryonic coelom.

The extraembryonic coelom divides the extraembryonic mesoderm into two layers: extraembryonic splanchnopleuric mesoderm, which lies adjacent to Heuser's membrane around the outside of the primitive yolk sac, and extraembryonic somatopleuric mesoderm, which lies adjacent to the cytotrophoblast layer of the embryo.

The chorionic cavity is enclosed by the chorionic plate, which is composed of an inner layer of somatopleuric mesoderm and an outer layer of trophoblast cells.

Clinical significance

Ultrasound

Mean gestational sac diameter by gestational age. The blue line is the mean, and the green area delimits the 5th and the 95th percentiles.^[1]

A: Gestational sac (GS), B: Crown rump length (CRL) of embryo, C: Amniotic sac, D: Yolk sac

The mean sac diameter (MSD) can effectively estimate gestational age^[2] between 5 and 6 weeks, with an accuracy of about +/- 5 days.^[3]

The yolk sac and embryo should be readily identified when the gestational sac reaches a certain size — a yolk sac should be seen when gestational sac is 20mm and a fetal pole should be seen when the gestational sac reaches 25mm.

Gestational sacs can be identified via ultrasound and are generally identified by the following 4 characteristics:

The sac is round or elliptical shape in longitudinal and transverse views
Surrounded by a white echogenic rim (choriodecidual reaction)
The sac is present in the uterine fundus
The sac is not implanted on the midline, but eccentrically (to one side of the uterine cavity line, without displacing it).

References

^ Papaioannou, George I.; Syngelaki, Argyro; Poon, Leona C.Y.; Ross, Jackie A.; Nicolaides, Kypros H. (2010). "Normal Ranges of Embryonic Length, Embryonic Heart Rate, Gestational Sac Diameter and Yolk Sac Diameter at 6–10 Weeks". Fetal Diagnosis and Therapy 28 (4): 207–219. doi:10.1159/000319589. ISSN 1421-9964.
Crown rump length before a gestational age of 6 weeks is extrapolated by assuming a gestational sac diameter of 0 at a gestational age of 2 weeks, corresponding to a fertilization age of 0 weeks. This extrapolated part is blurred because of uncertain values.
^ Karki DB, Sharmqa UK, Rauniyar RK (2006). "Study of accuracy of commonly used fetal parameters for estimation of gestational age". JNMA; journal of the Nepal Medical Association 45 (162): 233–7. PMID 17189967.
^ "Basic Imaging > Ultrasound of Early Pregnancy". Archived from the original on 2007-08-14. Retrieved 2007-10-13.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 胎児腹壁欠陥の出生前超音波診断 prenatal sonographic diagnosis of fetal abdominal wall defects
2. 胎児腹壁破裂（body stalk anomaly）および総排泄腔奇形の
産科学的新生児マネージメント obstetrical and neonatal management of body stalk anomalies and cloacal abnormalities
3. 消化管閉鎖症および閉塞の出生前診断 prenatal diagnosis of gastrointestinal atresia and obstruction
4. 副腎の外科解剖学 surgical anatomy of the adrenal glands
5. マウス遺伝子：育種戦略と遺伝子工学 mouse genetics breeding strategies and genetic engineering

English Journal

First-trimester diagnosis of body stalk anomaly using 2- and 3-dimensional sonography.

Murphy A1, Platt LD.Author information 1Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA. amurphy@mednet.ucla.eduAbstractTo determine the sonographic features of body stalk anomaly in the first trimester using 2-dimensional (2D) and 3-dimensional (3D) sonography, we conducted a retrospective analysis of all nuchal translucency sonographic examinations performed between January 1, 2006, and January 1, 2010, at our institution. From a total of 6952 nuchal translucency sonographic examinations, 4 cases of body stalk anomaly were identified. All cases were characterized by an absent umbilical cord and a large ventral wall defect with herniation of the abdominal contents into the extraembryonic coelom. Associated features included kyphoscoliosis, limb defects, and enlarged nuchal translucency measurements. Three-dimensional sonography was a useful adjunct to 2D techniques in determining the precise relationship of fetal structures to the amniotic cavity. Our case series emphasizes the importance of a thorough anatomic survey at the time of nuchal translucency screening and the value of 3D sonography in the delineation of first-trimester anomalies.
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine.J Ultrasound Med.2011 Dec;30(12):1739-43.
To determine the sonographic features of body stalk anomaly in the first trimester using 2-dimensional (2D) and 3-dimensional (3D) sonography, we conducted a retrospective analysis of all nuchal translucency sonographic examinations performed between January 1, 2006, and January 1, 2010, at our inst
PMID 22124010

Intestinal atresia and ectopia in a bovine fetus.

Lejeune B1, Miclard J, Stoffel MH, Meylan M.Author information 1Clinic for Ruminants, Vetsuisse Faculty, Bremgartenstr. 109a, 3012 Berne, Switzerland. beatrice.lejeune@knp.unibe.chAbstractA 2-year-old Red Holstein cow was presented with uterine torsion at 235 days of pregnancy. The fetus extracted by cesarean section had weak vital signs and marked abdominal distention. An edematous pouch that contained tubular structures with peristaltic activity was associated with the umbilical cord. Because of poor prognosis, both dam and fetus were euthanized. At necropsy, the fetus had severe distention of the forestomachs, abomasum, and proximal small intestine; absence of distal small intestine, cecum, and proximal colon; atresia of the 2 blind ends of the intestine; and atrophy of distal colon and rectum. The tubular structures associated with the umbilical cord were identified as the segments of intestine that were absent in the fetus. Intestinal atresia combined with ectopia may be caused by local ischemia during temporary herniation and rotation of the fetal gut into the extraembryonic coelom. The close connection between ectopic intestine and amniotic sheath of the umbilical cord in this case may have facilitated vascularization and allowed development and viability of the ectopic intestine.
Veterinary pathology.Vet Pathol.2011 Jul;48(4):830-3. doi: 10.1177/0300985810383872. Epub 2010 Oct 6.
A 2-year-old Red Holstein cow was presented with uterine torsion at 235 days of pregnancy. The fetus extracted by cesarean section had weak vital signs and marked abdominal distention. An edematous pouch that contained tubular structures with peristaltic activity was associated with the umbilical co
PMID 20926733

Expression pattern of Popdc2 during mouse embryogenesis and in the adult.

Froese A1, Brand T.Author information 1Cell and Developmental Biology, Theodor-Boveri-Institute of Biological Sciences, University of Würzburg, Würzburg, Germany.AbstractThe Popdc2 gene is a member of the Popeye domain containing gene family encoding membrane proteins with prominent expression in striated and smooth muscle tissue. After introducing a LacZ reporter gene into the Popdc2 locus, expression was studied during embryonic development and postnatal life. At embryonic day (E) 7.5, expression was present in cardiac and extraembryonic mesoderm. At E10.5, expression was found in heart, somites, and mesothelial cells lining the coelom. At E12.5, expression was present in the coelomic mesothelium, pericardial and myocardial layer of the heart, skeletal muscle, bladder, gut, and umbilical vessels. Postnatal expression was found in cardiac and skeletal muscle and in the smooth muscle layer of colon, rectum, and bladder. In the stomach, Popdc2 was exclusively present in the pyloric epithelium. In conclusion, Popdc2 is expressed in various muscle and nonmuscle cell types during embryonic development and in postnatal life.
Developmental dynamics : an official publication of the American Association of Anatomists.Dev Dyn.2008 Mar;237(3):780-7. doi: 10.1002/dvdy.21431.
The Popdc2 gene is a member of the Popeye domain containing gene family encoding membrane proteins with prominent expression in striated and smooth muscle tissue. After introducing a LacZ reporter gene into the Popdc2 locus, expression was studied during embryonic development and postnatal life. At
PMID 18189275

Japanese Journal

DEVELOPMENTAL TOXICITY POTENTIAL OF GRAYANOTOXIN I IN MICE AND CHICKS

KOBAYASHI Takashi,YASUDA Mineo,SEYAMA Issei
The Journal of Toxicological Sciences 15(4), 227-234, 1990-11-26
… In chicks, a single injection of 0.1-1.0 μg GTX I per egg into the extraembryonic coelom on day 1.5 or 2 of incubation, or into the amnionic cavity on day 3 or 4 of incubation induced neither embryotoxic nor teratogenic signs, but 10μg GTX I per egg showed lethal effects when applied on eath of those days. …
NAID 110001804836

Mononuclear cells in the extraembryonic and intraembryonic coelom of mouse embryo : a semithin light microscopic cytometry

SASAKI K.
Arch. Histol. Cytol. 52, 421-426, 1989
NAID 80004848638

Related Pictures

★リンクテーブル★

リンク元	「胚外体腔」
関連記事	「extraembryonic」「coelom」

「胚外体腔」

Gestational sac
	Contents in the cavity of the uterus seen at approximately 5 weeks of gestational age by obstetric ultrasonography.
	Artificially colored, showing gestational sac, yolk sac and embryo (measuring 3 mm as the distance between the + signs).
Details
Latin	saccus gestationalis, coeloma extraembryonicum, cavitas chorionica
Carnegie stage	6a
Days	12
Precursor	Heuser's membrane
Identifiers
Code	TE E5.8.0.0.1.0.1
Dorlands; /Elsevier	s_01/12716747
	Anatomical terminology

　　[★]

英: extraembryonic coelom, extraembryonic celom, exocoelom, exocelomic cavity
ラ: coeloma extra-embryonicum

「extraembryonic」

　　[★]

胚外の、(発生)胚体外の

関: exocelomic、extraembryonal

「coelom」

　　[★]

体腔

関: celom、celomic、coelomic

[PapaioannouSyngelaki2010-1] Papaioannou, George I.; Syngelaki, Argyro; Poon, Leona C.Y.; Ross, Jackie A.; Nicolaides, Kypros H. (2010). "Normal Ranges of Embryonic Length, Embryonic Heart Rate, Gestational Sac Diameter and Yolk Sac Diameter at 6–10 Weeks". Fetal Diagnosis and Therapy 28 (4): 207–219. doi:10.1159/000319589. ISSN 1421-9964.
Crown rump length before a gestational age of 6 weeks is extrapolated by assuming a gestational sac diameter of 0 at a gestational age of 2 weeks, corresponding to a fertilization age of 0 weeks. This extrapolated part is blurred because of uncertain values.

[pmid17189967-2] Karki DB, Sharmqa UK, Rauniyar RK (2006). "Study of accuracy of commonly used fetal parameters for estimation of gestational age". JNMA; journal of the Nepal Medical Association 45 (162): 233–7. PMID 17189967.

[3] "Basic Imaging > Ultrasound of Early Pregnancy". Archived from the original on 2007-08-14. Retrieved 2007-10-13.

匿名

検索

案内

案内

extraembryonic coelom