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The Ceolomic or Body Cavity
The Ceolomic or body cavity develops from the intraembryonic coelom formed within the intraembryonic mesoderm.
Its formation begins with the appearance of intercellular clefts in the lateral mesoderm that gradually becomes the intraembryonic coelom and subdivides the mesoderm into two: the somatic and splanchnic mesodermal layers. The splanchnic layer is continuous with the mesoderm of the wall of the yolk sac.
Initially, the right and left sides of the intraembryonic coelom are in open connection with the extraembryonic coelom, but following embryonic folding, this connection is lost with a resultant enlargement of the intraembryonic coelom that now extends from the thoracic to the pelvic region.
The intraembryonic coelom has walls of skin, connective tissue, bone, muscles, and a serous membrane. The muscular diaphragm divides the coelom into an upper thoracic (chest) cavity that contains the heart and lungs and a lower abdomino-pelvic cavity that contains the intestines, liver, spleen, stomach, pancreas, kidneys, and reproductive organs.
SECTION B
DEVELOPMENTAL EVENTS
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What are the developmental events?
Events associated with human development include:
Gametogenesis
Release of the Gametes
The female Reproductive Cycles
Gamete transport
Gamete-in-transit modifications i.e. sp. cell activation
Fertilization
Cleavage
Morula and Blastocyst formation (Blastogenesis)
Differentiation of the cell masses of the Blastocyst (Embryogenesis)
Implantation
Development of Bilaminar germ cell
Gastrulation: the development of Trilaminar germ cell
Organogenesis: Development of primordial structures.
Neurulation
Somitogenesis
Embryonic folding
Development of the placenta.
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