Coelomic Cavity Development

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Coelomic Cavity cartoon
Intra-embryonic coelom week 3-4 (GA 5-6)
coelom - (Greek, koilma = cavity) Term used to describe a fluid-filled cavity or space. Placental vertebrate development have both extraembryonic (outside the embryo) and intraembryonic (inside the embryo) coeloms.

The extra-embryonic coeloms include the yolk sac, amniotic cavity and the chorionic cavity information on these spaces can also be found on placental development pages.

The intra-embryonic coelom is initially a single space located in the lateral plate mesoderm, that will later form the 3 major body cavities: pleural, pericardial and peritoneal.

All intra-embryonic cavities are fluid filled and developing organs push against a wall of the cavity, generating a double coat (serosal/adventital) surrounding an organ (for example the lungs). The serous membrane is the epithelium (squamous) and its associated underlying loose connective tissue.

Coelom Links: Introduction | Lecture - Week 3 Development | Lecture - Mesoderm Development | Placenta - Membranes | Category:Coelomic Cavity
Historic Embryology: 1891 peritoneal | 1897 human coelom | 1910 | 1924 serous

Some Recent Findings

  • Review - Coelomic epithelium-derived cells in visceral morphogenesis[1] "Coelomic cavities of vertebrates are lined by a mesothelium which develops from the lateral plate mesoderm. During development, the coelomic epithelium is a highly active cell layer, which locally is able to supply mesenchymal cells that contribute to the mesodermal elements of many organs and provide signals which are necessary for their development. ... Body wall, heart, liver, lungs, gonads, and gastrointestinal tract are populated by cells derived from the coelomic epithelium which contribute to their connective and vascular tissues, and sometimes to specialized cell types such as the stellate cells of the liver, the Cajal interstitial cells of the gut or the Sertoli cells of the testicle."
More recent papers  
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.

  • This search now requires a manual link as the original PubMed extension has been disabled.
  • The displayed list of references do not reflect any editorial selection of material based on content or relevance.
  • References also appear on this list based upon the date of the actual page viewing.

References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.

More? References | Discussion Page | Journal Searches | 2019 References

Search term: Coelomic Cavity Development | Amniotic Cavity Development | Yolk Sac Development | Cardiac Cavity Development | Pleural Cavity Development | Peritoneal Cavity Development

Older papers  
These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.

See also the Discussion Page for other references listed by year and References on this current page.

  • Embryo-fetal erythroid megaloblasts in the human coelomic cavity[2] "The coelomic cavity is part of the extraembryonic mesoderm, surrounding amniotic cavity, embryo, and yolk sac in the early gestation. It is now believed to represent an important transfer interface and a reservoir of nutrients for the embryo. Coelocentesis by ultrasound-guided transvaginal puncture offers an easier access to the early human embryo, from 28 days post-fertilization. However, despite some studies about its biochemical composition being reported, our knowledge about the presence of cellular elements and their quality in this compartment are still limited. Here we studied human coelomic fluids sampled from 6.6 (48 days) to 10 weeks of gestation, demonstrating the presence of functional embryonic erythroid precursors, that is, megaloblasts in the coelomic cavity."


  • Describe the development of the intra- and extra-embryonic coeloms.
  • Describe the processes involved in the development of the three divisions of the intra-embryonic coelom; pericardium, pleural cavities and peritoneum.
  • Describe the fate of the extra embryonic coelom.
  • Describe the development of the diaphragm.

Development Overview

Extraembryonic Coelom
cavity surrounding the developing embryo
coelomic portalstransient communication between extra/intracoelom
Intraembryonic Coelom
horseshoe shaped structure forms 3 main cavities
Neural Tube

pericardial cavity
Ventricular space
L/R pleural cavities
Spinal canal
peritoneal cavity
(More? Neural System Development)

Extraembryonic Coelom

Human embryo (week 4) extra embryonic coeloms.
Human embryo enclosed in extraembryonic membranes surrounding coeloms.

Amniotic cavity

The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then lined by ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to eventually fuse with the chorionic membrane during week 8 of development. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryonic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus. The presence of this membrane led to the description of reptiles, bird, and mammals as "amniotes".

Chorionic cavity

The fluid-filled extra-embryonic coelom (cavity) formed initially from trophoblast and extra-embryonic mesoderm that forms placenta. Chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange. In humans, this cavity is lost during week 8 when the amniotic cavity expands and fuses with the chorion.

Yolk sac

An extra-embryonic membrane which is endoderm origin and covered with extra-embryonic mesoderm. Yolk sac lies outside the embryo connected initially by a yolk stalk to the midgut with which it is continuous with. The endodermal lining is continuous with the endoderm of the gastrointestinal tract. The extra-embryonic mesoderm differentiates to form both blood and blood vessels of the vitelline system. In reptiles and birds, the yolk sac has a function associated with nutrition. In mammals the yolk sac acts as a source of primordial germ cells and blood cells. Note that in early development (week 2) a structure called the "primitive yolk sac" forms from hypoblast, this is an entirely different structure.


The allantois is present in reptiles, birds, acts in respiration and waste storage. In mammals, other than marsupials, associated with chorion blood vessel development and the urinary bladder.

The human allantois forms from Carnegie stage 7 forms an endoderm cloacal diverticulum adjacent to the yolk sac. It extends from the umbilicus into the connecting stalk. Vascular development occurs within the adjacent connecting stalk mesoderm associated with placental cord vessel development. Separate vascular development of the allantois occurs initially in the distal tip mesoderm.

Later septation of the cloacal has the allantois associated ventrally with the urogenital sinus. It lies at the superior end of the primitive urinary bladder and forms the urachus. Postnatally, the urachus degenerates to form a fibrous ligament (median umbilical ligament) between the urinary bladder to the umbilical region.

Intra-embryonic Coelom

peritoneal and retroperitoneal

Stage 13 image 073.jpg

Week 5 pericardial and peritoneal cavities

Pericardial Cavity

Links: Cardiovascular System Development

Pleural Cavity


Reflections of the Pleura

Links: Respiratory System Development

Peritoneal Cavity

Embryo Stage 13 Peritoneal Cavity

Stage 13 image 073.jpgStage 13 image 076.jpg

Links: Gastrointestinal Tract Development

Week 8


Stage 22 image 200.jpg


Stage 22 image 203.jpg

Carnegie stage 22

Mesentery and Retroperitoneal


Stages in the development of the bursa omentalis, the greater omentum, and the fusion of the latter with the transverse mesocolon.


Links: Gastrointestinal Tract Development


The epithelial covering of coelomic organs and also line their cavities.

  • Contribute to the vasculature of the heart and the intestinal tract.
  • Undergo epithelial-mesenchymal transition (EMT), migration, and differentiation into endothelial cells, vascular smooth muscle cells, and pericytes.
    • contribute most of the vascular smooth muscle to the respiratory and gastrointestinal tract. (Remainder derived from endothelium?)


  1. Ariza L, Carmona R, Cañete A, Cano E & Muñoz-Chápuli R. (2016). Coelomic epithelium-derived cells in visceral morphogenesis. Dev. Dyn. , 245, 307-22. PMID: 26638186 DOI.
  2. Renda MC, Giambona A, Fecarotta E, Leto F, Makrydimas G, Renda D, Damiani G, Jakil MC, Picciotto F, Piazza A, Valtieri M & Maggio A. (2010). Embryo-fetal erythroid megaloblasts in the human coelomic cavity. J. Cell. Physiol. , 225, 385-9. PMID: 20533375 DOI.


Ariza L, Carmona R, Cañete A, Cano E & Muñoz-Chápuli R. (2016). Coelomic epithelium-derived cells in visceral morphogenesis. Dev. Dyn. , 245, 307-22. PMID: 26638186 DOI.


Funayama N, Sato Y, Matsumoto K, Ogura T & Takahashi Y. (1999). Coelom formation: binary decision of the lateral plate mesoderm is controlled by the ectoderm. Development , 126, 4129-38. PMID: 10457021

Search PubMed

Search Pubmed: Coelomic Cavity Development | pericardial cavity development | pleural cavity development | peritoneal cavity development

Additional Images


Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)


  • atresia- obstruction.
  • eppiglottis- develops from hypobrachial eminence.
  • fistula- abnormal comunication.
  • hypopharyngeal eminence- fusion of 3rd pharyngeal arches, precursor of root of tongue.
  • laryngotracheal groove- forms on anterior (ventral) wall of pharynx, gives rise to larynx, trachea, respiratory tree.
  • larynx- lining from endoderm, cartilage from pharyngeal arch 4 and 6.
  • lung buds- primordia of lungs.
  • parietal pleura-outer lining of pleural cavity derived from epithelia of pericardioperitoneal canals from intra-embryonic coelom.
  • pleural cavity- walls derived from pericardioperitoneal canals -> intra-embryonic coelom ->coelomic spaces -> lateral mesoderm -> mesoderm.
  • pleuropericardial fold- restricts the communication between pleural cavity and pericardiac cavity, contains cardinal vein and phrenic nerve.
  • pleuroperitoneal membrane- forms inferiorly at transverse septum to separate peritoneum from pleural cavity.
  • septum transversum- mesoderm separating thoracic cavity and yolk sac, forms central tendon of diaphragm (and some of liver?).
  • stenosis- narrowing
  • surfactant- a detergent secreted by Type 2 alveolar cells between alveolar epithelium. Functions to lower surface tension, allowing lungs to remain inflated.
  • visceral pleura- inner lining of pleural cavity derived from contact epithelia with lung bud of pericardioperitoneal canals from intra-embryonic coelom.

System Links: Introduction | Cardiovascular | Coelomic Cavity | Endocrine | Gastrointestinal Tract | Genital | Head | Immune | Integumentary | Musculoskeletal | Neural | Neural Crest | Placenta | Renal | Respiratory | Sensory | Birth

Glossary Links

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Cite this page: Hill, M.A. (2019, December 10) Embryology Coelomic Cavity Development. Retrieved from

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G