Coelomic Cavity Development
- 1 Introduction
- 2 Some Recent Findings
- 3 Objectives
- 4 Development Overview
- 5 Extraembryonic Coelom
- 6 Intraembryonic Coelom
- 7 Week 8
- 8 Mesentery and Retroperitoneal
- 9 Mesothelium
- 10 References
- 11 Additional Images
- 12 Terms
- 13 Glossary Links
- 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 extraembryonic coeloms include the yolk sac, amniotic cavity and the chorionic cavity. The initial single intraembryonic coelom located in the lateral plate mesoderm will form the 3 major body cavities: pleural, pericardial and peritoneal.
The intraembryonic coelom is the primitive cavity that lies within the developing embryo that will form the 3 major body cavities: pericardial, pleural, peritoneal. The coelom forms very early in embryogenesis and is much later paritioned inferiorly by the diaphragm and pleuroperitoneal membrane; and superiorly initially by the pleuropericardial fold between the heart and lungs. The intraembryonic coelom communicated through coelomic portals (at the level of midgut herniation) with the extraembryonic coelom.
All 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|
|System Links: Introduction | Cardiovascular | Coelomic Cavity | Endocrine | Gastrointestinal Tract | Genital | Head | Immune | Integumentary | Musculoskeletal | Neural | Neural Crest | Placenta | Renal | Respiratory | Sensory | Birth|
Some Recent Findings
- 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.
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".
The fluid-filled extraembryonic coelom (cavity) formed initially from trophoblast and extraembryonic 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.
An extraembryonic membrane which is endoderm origin and covered with extraembryonic 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.
Mesentery and Retroperitoneal
Stages in the development of the bursa omentalis, the greater omentum, and the fusion of the latter with the transverse mesocolon.
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?)
- 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 intraembryonic coelom.
- pleural cavity- walls derived from pericardioperitoneal canals -> intraembryonic 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 intraembryonic coelom.
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Cite this page: Hill, M.A. (2020, June 4) Embryology Coelomic Cavity Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Coelomic_Cavity_Development
- © Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G