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 extra-embryonic (outside the embryo) and intra-embryonic (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 placenta development pages.

The intra-embryonic coelom (coelomic cavity) forms within the lateral plate mesoderm early in embryonic development (week 3-4 (GA 5-6). This single space wall will undergo amesenchymal epithelial transition. The space then undergoes complex morphological changes of folding and partitioning during the development of the 3 major body cavities (pleural, pericardial and peritoneal). Portions of the coelomic cavity wall will also contribute to other organs (adrenal, ovary, testis).

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 - Coelomic Cavity  
1891 peritoneal | 1897 human coelom | 1910 Coelom and Diaphragm | 1924 serous

Some Recent Findings

  • Review - Mesothelial-mesenchymal transitions in embryogenesis[1] "Most animals develop coelomic cavities lined by an epithelial cell layer called the mesothelium. Embryonic mesothelial cells have the ability to transform into mesenchymal cells which populate many developing organs contributing to their connective and vascular tissues, and also to organ-specific cell types. Furthermore, embryonic mesothelium and mesothelial-derived cells produce essential signals for visceral morphogenesis. We review the most relevant literature about the mechanisms regulating the embryonic mesothelial-mesenchymal transition, the developmental fate of the mesothelial-derived cells and other functions of the embryonic mesothelium, such as its contribution to the establishment of left-right visceral asymmetries or its role in limb morphogenesis."
  • Human coelomic fluid investigation: A MS-based analytical approach to prenatal screening[2] "Coelomic fluid (CF) is the earliest dynamic and complex fluid of the gestational sac. CF contains maternal cells and proteins produced by embryonic cells, tissues and excretions. The biochemical composition of CF is modified throughout the first trimester of pregnancy and its protein profile reflects both physiological/pathological changes affecting the embryo and mother. Identification of variations in the balance of proteins might indicate particular types of pathologies, or ascertain specific genetic disorders. A platform utilizing protein enrichment procedures coupled with shotgun identification and iTRAQ differentiation provided the identification and quantitation of 88 unique embryonic proteins. It is relevant to note that chromosome X protein CXorf23 was found suggesting the embryo sex. Foetal sex was determined by Quantitative Fluorescent Polymerase Chain Reaction (QF-PCR) on coelomic cells, foetal tissues and maternal white blood cells, with a 100% concordance rate between iTRAQ-MS/MS and QF-PCR data."
More recent papers  
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More? References | Discussion Page | Journal Searches | 2019 References | 2020 References

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

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.

  • Review - Coelomic epithelium-derived cells in visceral morphogenesis[3] "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."
  • Embryo-fetal erythroid megaloblasts in the human coelomic cavity[4] "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

Coelomic Cavities
Extra-embryonic Coelom Intra-embryonic Coelom Other (fluid-filled spaces)
outside the embryo inside the embryo between and within embryo
chorionic sac pericardial coelomic portals - transient communication between extra and intra
amniotic sac pleural ventricular - cavities within and surrounding central nervous system
yolk sac peritoneal renal - cavities within the kidney and bladder

Extra-embryonic Coelom

Human embryo (week 4) extra-embryonic coeloms.
Human embryo enclosed in extra-embryonic 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. The 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.


Tammar Wallaby Embryo
Tammar Wallaby Embryo allantois[5]

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

The intra-embryonic coelom forms as a single cavity appearing in the lateral plate mesoderm during week 3. This single cavity (coelom) divides the lateral plate into the somatic and splanchnic mesoderm and will later be portioned into the three main body cavities: pericardial, pleural and peritoneal cavities.

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. Carmona R, Ariza L, Cano E, Jiménez-Navarro M & Muñoz-Chápuli R. (2018). Mesothelial-mesenchymal transitions in embryogenesis. Semin. Cell Dev. Biol. , , . PMID: 30243860 DOI.
  2. Aiello D, Giambona A, Leto F, Passarello C, Damiani G, Maggio A, Siciliano C & Napoli A. (2018). Human coelomic fluid investigation: A MS-based analytical approach to prenatal screening. Sci Rep , 8, 10973. PMID: 30030477 DOI.
  3. 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.
  4. 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.
  5. Menzies BR, Pask AJ & Renfree MB. (2011). Placental expression of pituitary hormones is an ancestral feature of therian mammals. Evodevo , 2, 16. PMID: 21854600 DOI.


Hall NJ, Drewett M & Burge D. (2019). Nutritional role of amniotic fluid: clues from infants with congenital obstruction of the digestive tract. Arch. Dis. Child. Fetal Neonatal Ed. , 104, F199-F201. PMID: 29666202 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.


Cindrova-Davies T, Jauniaux E, Elliot MG, Gong S, Burton GJ & Charnock-Jones DS. (2017). RNA-seq reveals conservation of function among the yolk sacs of human, mouse, and chicken. Proc. Natl. Acad. Sci. U.S.A. , 114, E4753-E4761. PMID: 28559354 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

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

Additional Images


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Pages where the terms "Historic" (textbooks, papers, people, recommendations) 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, interpretations and recommendations 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

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Cite this page: Hill, M.A. (2024, April 22) Embryology Coelomic Cavity Development. Retrieved from

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