MCQ – 68648

Correct Answer � D Explanation

Ans. d. Dilators of pupil

Smooth muscles of iris (constrictor and dilator pupillae)

• The sphincter and dilator pupillae muscles of the iris are derived from the ectoderm.
• The region between the optic cup and the overlying surface epithelium is filled with loose mesenchyme.
• The sphincter and dilator pupillae muscles form in this tissue.

Derivatives of Mesoderm

• All connective tissue i.e. superficial and deepfascia(ligaments, tendons, aponeurosis, dermis of skin’, adipose reticular tissue, cartilage and bone)
• All cardiovascular system i.e. heart, blood vessels, lymphatic and blood cells.
• All Musculoskeletal system i.e. bone, cartilage, tendon, ligaments and muscles (smooth, striated and cardiac) musculature of iris (sphincter and dilator pupillae) which are ectodermale
• All Reproductive system i.e. ovary, uterine tubes, uterus and upper vagina in females; testis, epididymis, ductus deferens, prostate (inner glandular zone) seminal vesicle and ejaculatory duct in males.
• Except epithelium of greater part of vagina, vestibule and inner surface of labia minora in female and greater part of prostate (except inner glandular zone) is endodermal.
• Outer surface of labia ininora and whole labia majora are ectodermal
• All urinary system i.e. kidney, ureters, trigone of bladder, posterior part of female urethra, posterior part of urethra (upper half) of males and inner glandular zone of prostate
• Epithelium of urinary bladder (except trigone), female urethra (except posterior wall), male urethra (except prostatic part which is mesodermal and penile urethra which is ectodermal) and most of prostate (except inner glandular zone) are endodermal
• Mesothelial lining of –pleural, pericardial, and peritoneal cavities^e; and of tunica vaginalis, bursae and
• Dentine of teeth^e; (enamel is ectodermal’)
• Duramater and Microgliae
• Except these all other nervous system i.e. neurons, neuroglia and schwann cells are ectodermal
• Eye i.e. substance of cornea, sclera, choroid, ciliary body and iris
• Except anterior epithelium of cornea, epithelium of conjunctiva, epithelium of ciliary and iris; iris muscles and lens are ectodermal.