Coelomic Cavity and its
Derivatives - text only page
Embryo*Selected Human (high
1 | Introduction
2 | Questions
3 | Pig
4 | Human
5 | Selected
page | WWW
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
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.
- Human Embryology (2nd ed.) Larson Ch6
- The Developing Human: Clinically Oriented
Embryology (6th ed.) Moore and Persaud Ch9:
- Before we Are Born (5th ed.) Moore and
Persaud Ch10 p181-195
- Essentials of Human Embryology Larson Ch6
- Human Embryology Fitzgerald and Fitzgerald
Ch5 p29-32, Ch7 p47,48
- Additional References
- Search PubMed- Medline
- Describe the development of the intra- and
- 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
- Describe the development of the
- Review the development of the 3-layered
embryo, with particular reference to the
antero-posterior and lateral folding
- Examine the 6mm pig and 27mm human embryo
microfiche cards identifying the main features
of the developing coelom.
- Identify the diaphragm in the 27mm human
embryo and relate this to the development of the
- Discuss the developmental anomalies
associated with the formation of the
cavity surrounding the developing
transient communication between
horseshoe shaped structure forms 3
(not part of this section)
(see neural dev notes)
Database Online Mendelian
Inheritence in Man Database.
Internet Search OMIM database with the keyword
"coelom" "peritoneum" "pleural cavity" or the above
Note: This database is an external link,
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A is available for these computers.
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- A Selected List of References from March
1999 search results for and is available
for these computers.
1. What are the four main developmental
components of the diaphragm.
2. What is the septum transversum
3. Describe the developmental observations
associated with diaphragmatic hernia and its
consequences on the individual with the
4. How does the innervation of the diaphragm
Human (high power)
The extent of the coelomic cavity is best seen on
the sagittal sections of the pig embryo. G7:
identify the pericardial cavity and its
continuation posteriorly into the still small
pleural cavity (pleuroperitoneal canals).The
pleuroperitoneal (pericardio-peritoneal) canal.
one of the lung buds is seen embedded in the dense
tissue that is surrounded by the coelomic
cavity.The abdominal (peritoneal) cavity is clearly
continuous with the extra embryonic coelom and
parts of the intestinal loop and accompanying
mesentery are visible entering the umbilical
The most cranial part of the coelom visible in
cross sections is the pericardial cavity and from
this level caudally it can be seen extending to the
level of the liver, but anterior to it (D6). B7-C5:
Posteriorly and cranially this cavity communicates
with the primitive pleural cavity which are two
canals connecting the pericardial and peritoneal
cavities (C6-7, D1-6).
These two channels are separated from the
pericardium by a fold containing the common
cardinal veins either side. (Pleuropericardial
folds - see development of diaphragm).
The peritoneal cavity is extensive; it consists of
two, adjoining halves and a small cranial
outpocketing next to the stomach, the lesser sac.
Further caudally this cavity extends as far as the
region of the urorectal septum E7 (tail). Much of
the peritoneal cavity is occupied by the two parts
of the mesonephros, which reduce most of the cavity
to two crescent-shaped clefts.
In the human embryo, the separation of the three
cavities of coelom is complete.
: The pericardial cavity.
E1-7: The pleural cavity, almost the same
frames, indicating the nearby equal extent of the
two cavities at this stage, but also that
eventually the pleural cavities will become much
larger. E3-7: The diaphragm can be seen as a thin,
distinct membrane around the liver. Two derivatives
of the coelomic epithelium are to be observed
F1-3: The adrenal glands. Notice the large
fetal cortex, (most of the gland) and the narrow
(more compact and darker staining) early permanent
cortex encapsulating it.
The spleen develops in the dorsal mesogastrium and
appears as a dense body on it lateral to the left
adrenal gland and kidney. Review in Endocrine
G1: The gonads are also in part derivatives
of the coelomic epithelium but they will be
discussed with the rest of the genital system.
The caudal extent of the peritoneal cavity; this
appears as the rectovesical pouch in the male or as
the rectouterine pouch in the female.
Human Embryo- high
The histological appearance of the fetal adrenal
cortex is seen.
Fetal and permanent adrenal cortex. The medulla of
the adrenal gland is of neural crest origin and it
is not yet encapsulated by the cortex.
- Notes from the Embryology Program compiled and
written by Dr Mark Hill. Some notes derived from
- Note Links to OMIM Entries are copies of originals
for computers without internet access. Computers with
internet access can directly access the database.
Date Last Modified: 11/3/99
This site maintained by Dr M. Hill