Question

Which one of the following is not mesodermal in origin?
A. Circulatory system
B. Nervous system
C. Muscular system
D. Skeletal system

Answer 1

Hint:Transformation of the blastula into the gastrula with three primary germ layers by rearrangement of the cells is called gastrulation or formation of germ layers. There are three germ layers called ectoderm, mesoderm, and endoderm. They serve as the initial rudiments of all future tissues and organs of the offspring’s tissue

Complete answer:
Each germ layer gives rise to specific tissues, organs, and organ systems. The germ layer has the same fate in all animals.
Mesoderm: It produces -
a. Dermis of the skin
b. Most muscles, connective tissues
c. Peritoneum
d. Kidneys
e. The cortex of the adrenal gland
f. Gonads
g. Urinary and reproductive ducts
h. Heart blood and lymph vessels
i. Spleen
j. Wall of gut except for its lining epithelium
k. Pericardium and pleural
l. Sclera and choroid of eye
m. Most of skeleton
n. Dentine of teeth
o. Mesenteries
p. Notochord
Since the circulatory system, muscular system, and skeletal system are mesodermal in origin.

So the correct answer is option is B. Nervous system.

Additional information:
Endoderm. Forms lining of gut except that of stomodaeum a proctodaeum, gastric and intestinal glands, tongue epithelium, liver, pancreas, anterior lobe of the pituitary gland, thyroid gland, parathyroid gland, thymus glands, the lining of the trachea, bronchi and lungs, lining of the urinary bladder, lining of the middle ear, primordial germ cells and the greater part of prostrate.

Note: Ectoderm gives rise to epidermis skin and epidermal derivatives, nervous system, medulla of the adrenal gland, posterior and intermediate lobes of the pituitary gland, pineal gland, eye, internal ear, nasal epithelium, the lining of stomodaeum and proctodaeum, lining of external auditory canal, lacrimal glands, salivary glands and enamel of teeth. So the nervous system is of ectodermal origin.