MCAT Biology › Gastrulation and Embryonic Germ Layers
From which of the following germ layers does the circulatory system arise?
Mesoderm
Ectoderm
Endoderm
Neural crest
The circulatory system arises from the mesoderm. Other mesoderm structures include the muscles, bones, gonads, and kidneys.
The ectoderm gives rise to the epidermis, nervous system, and lens of the eye. The neural crest originates from ectoderm cells.
The endoderm gives rise to several internal organs, including the liver and pancreas, as well as the linings of the digestive and respiratory tracts.
From which of the following germinal layers does the retina of the eye originate?
Ectoderm
Mesoderm
Endoderm
Somites, which are not associated with a germ layer
The retina of the eye originates as an outpouching of the diencephalon. The diencephalon is one of the five secondary vesicles in the early development of the neural tube, which is derived from the ectodermal germ layer.
The ectoderm gives rise to the epidermis, central nervous system, inner ear, and the lens of the eye.
Somites are small regions of specialized mesoderm, which give rise to the skeletal muscles and bones of the body.
A new born is assesed to have congenital nerve conduction defects. From which germ layer would this problem originate?
Ectoderm
Endoderm
Mesoderm
Blastula
Gastrula
The correct answer is the ectoderm. The ectoderm is responsible for generating nervous tissue and glial cells, among other features.
Ectoderm differntiates into the epidermis, nervous system, eye lens, and hair.
Mesoderm differentiates into muscle, cardiac and skeletal systems, blood, and spleen.
Endoderm differentiates into the lining of internal organs, like the digestive tract and respiratory tract.
A newly born child is having difficulty breathing and digesting food. A close medical examination has revealed an improperly formed inner lining to the digestive and respiratory systems. Which of the following is the most likely cause of the medical problem?
An abnormality has occurred in the development of the endoderm
There is not enough information to determine a likely cause
A disease affecting the ectoderm germ layer
A disruption of the mesoderm during development
Genetic abnormalities in both the mesoderm and ectoderm
Gastrulation is the formation of the three layers of the embryo: ectoderm, endoderm, and mesoderm. The endoderm gives rise to the lining of the digestive system and respiratory system. A defect in these tissues suggests a problem of that germ layer during development. The ectoderm gives rise to the nervous system and epidermis. The mesoderm gives rise to the muscle and skeletal systems.
Which of the following structures does not arise from the endoderm?
Muscles
Liver
Lungs
Pancreas
The endoderm gives rise to most of the internal organs, including the lining of the digestive tract, the liver and pancreas, and the respiratory system.
Muscles and bones are derived from the mesoderm.
Which of the following is NOT a major germ layer formed during gastrulation?
Cytoderm
Mesoderm
Endoderm
Ectoderm
The correct answer is cytoderm.
There are three major germ layers formed during gastrulation: the ectoderm, mesoderm, and endoderm. Major structures form from these germ layers over the course of embryogenesis and development.
Which of the following structures does not arise from the mesoderm?
Respiratory system
Musculoskeletal system
Circulatory system
Genitourinary system
The mesoderm gives rise to muscles, bones, the circulatory system, the gonads, and the kidneys. Think of the mesoderm as the means by which your body gets around on a daily basis: muscles and bones, heart to pump blood, and kidneys to excrete waste.
The respiratory system arises from the endoderm.
The mesoderm germ layer eventually gives rise to the formation of the __________.
muscles
lining of the respiratory system
lining of the digestive system
nervous system
epidermis
The mesoderm gives rise to the muscles among other structures. The other answers are derived from the ectoderm or endoderm.
The kidneys arise from which of the three embryonic germ layers?
Mesoderm
Ectoderm
Endoderm
Notochord region
None of these choices are correct
The three embryonic germ layers are the ectoderm, mesoderm, and endoderm. The mesoderm gives rise to bone, muscle, the urinary system, and the kidneys. Ectoderm develops into the nervous system, dermis, hair, nails, eyes, and ears. The endoderm develops into the lining of internal organs, such as the lungs and the gastrointestinal tract. The notochord is not an embryonic layer and, like the kidneys, arises from the mesoderm.
Which embryonic structure is a precursor to the spinal cord?
Neural tube
Notochord
Spemann's organizer
Blastocoel
The neural tube is a structure derived from the ectoderm that is found in chordates. The neural tube is formed by the closing of the neural folds, and runs along the dorsal-ventral axis of the developing embryo. Cells within the neural tube give rise to the neural crest. Additionally, the mature neural tube continues to develop into the central nervous system.