Q.92 Cardiac and cerebral tissues are derived from the following germ layers respectively
(A) Ectoderm and mesoderm (B) Mesoderm and ectoderm
(C) Mesoderm and endoderm (D) Endoderm and ectoderm
Cardiac tissue derives from the mesoderm, while cerebral tissue derives from the ectoderm, making option (B) Mesoderm and ectoderm the correct answer.
Option Analysis
Option (A) Ectoderm and mesoderm: Incorrect, as ectoderm forms nervous system tissues like the brain and cerebral structures, not cardiac muscle, while mesoderm does form heart tissue.
Option (B) Mesoderm and ectoderm: Correct, since cardiac tissue originates from splanchnic mesoderm during heart development, and cerebral tissue from neural ectoderm via neurulation.
Option (C) Mesoderm and endoderm: Incorrect, as endoderm contributes to gut and visceral organs but not cerebral tissues.
Option (D) Endoderm and ectoderm: Incorrect, because endoderm does not form cardiac tissue, which arises specifically from mesoderm.
Germ Layer Derivatives
During gastrulation, the three primary germ layers form: ectoderm (outer), mesoderm (middle), and endoderm (inner). Mesoderm differentiates into cardiomyocytes via cardiogenic mesoderm fields, forming the myocardium around 18-19 days post-fertilization. Ectoderm gives rise to neuroectoderm, which forms the brain and cerebral cortex through neural tube development.
Introduction: Cardiac and Cerebral Tissues Germ Layers Explained
In embryonic development, cardiac and cerebral tissues germ layers determine organ formation during gastrulation. Cardiac tissue arises from mesoderm, while cerebral tissue derives from ectoderm—key facts for CSIR NET Life Sciences aspirants. Understanding these origins clarifies tissue differentiation and aids exam success.
Germ Layers in Embryonic Development
Gastrulation establishes ectoderm, mesoderm, and endoderm, each yielding specific tissues. Ectoderm forms epidermis and neural structures; mesoderm yields muscles, bones, and heart; endoderm produces linings for digestive and respiratory tracts. Signals like BMP and Wnt guide mesoderm into cardiogenic regions.
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Ectoderm: Nervous system, brain, spinal cord.
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Mesoderm: Heart myocardium, blood vessels, connective tissues.
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Endoderm: Gut epithelium, liver, lungs.
Cardiac Tissue from Mesoderm
Cardiac tissue originates from lateral plate mesoderm, splitting into somatic and splanchnic layers. Precursors in the primitive streak migrate to form heart fields, yielding endocardial tubes and myocardium by week 3. Factors like Nkx2.5 and GATA4 drive cardiogenesis.
Cerebral Tissue from Ectoderm
Cerebral tissues develop from neuroectoderm, induced by neural plate formation and folding into the neural tube. This yields forebrain structures like cerebrum via prosencephalon. Sonic hedgehog and FGF signaling pattern the cortex.
CSIR NET Exam Relevance
For competitive exams like CSIR NET, questions on cardiac and cerebral tissues germ layers test embryology basics. Option (B) Mesoderm and ectoderm is standard; memorize derivatives: mesoderm (heart/muscle), ectoderm (CNS), endoderm (viscera). Practice reinforces retention.
