Extra embryonic membranes
- During development of chick and other higher vertebrates,
certain tissue or structure temporarily or permanently do not
enter into the formation of embryo, but are devoted in one way
or another for care and maintenance of developing embryo.
These are called foetal membranes or extra embryonic sac or
extra embryonic membranes
- In higher terrestrial animals only
1. Amnion
- Surround embryo and forms amniotic sac which acts as
private aquarium
- Protect embryo from mechanical shock and desiccation
2. Chorion
- Outermost membrane surrounding the rest of membranes
- Helps in respiration
3. Yolk sac
- Yolk filled membrane
- First act as respiratory organ and then as digestive organ
- Also acts as haemopoetic organ
4. Allantois
- Acts as extra embryonic kidney and store nitrogenous waste
- Also act as respiratory surface
, Development of extra embryonic membranes (in telolecithal
egg)
- During neurulation lateral plate mesoderm splits into somatic
and splanchnic mesoderm.
- Somatic layer of mesoderm and ectoderm called somatopleure
- Splanchnic layer of mesoderm and endoderm called
splachnopleure
- During development, somatopleure and splanchnopleure
spread behind the boundry of embryo over yolk mass
A. Development of amnion and chorion
- Develops from extra embryonic somatopleure
Diag. Development showing formation of folds
- Somatopleure elevates around embryo as four folds (cephalic
amniotic fold-1, lateral amniotic fold-2 and caudal amniotic
fold-1)
- During development of chick and other higher vertebrates,
certain tissue or structure temporarily or permanently do not
enter into the formation of embryo, but are devoted in one way
or another for care and maintenance of developing embryo.
These are called foetal membranes or extra embryonic sac or
extra embryonic membranes
- In higher terrestrial animals only
1. Amnion
- Surround embryo and forms amniotic sac which acts as
private aquarium
- Protect embryo from mechanical shock and desiccation
2. Chorion
- Outermost membrane surrounding the rest of membranes
- Helps in respiration
3. Yolk sac
- Yolk filled membrane
- First act as respiratory organ and then as digestive organ
- Also acts as haemopoetic organ
4. Allantois
- Acts as extra embryonic kidney and store nitrogenous waste
- Also act as respiratory surface
, Development of extra embryonic membranes (in telolecithal
egg)
- During neurulation lateral plate mesoderm splits into somatic
and splanchnic mesoderm.
- Somatic layer of mesoderm and ectoderm called somatopleure
- Splanchnic layer of mesoderm and endoderm called
splachnopleure
- During development, somatopleure and splanchnopleure
spread behind the boundry of embryo over yolk mass
A. Development of amnion and chorion
- Develops from extra embryonic somatopleure
Diag. Development showing formation of folds
- Somatopleure elevates around embryo as four folds (cephalic
amniotic fold-1, lateral amniotic fold-2 and caudal amniotic
fold-1)
