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Well, I was just going through an article on eye, where in fun facts it was mentioned that newly born (for initial 1 to 3 months) babies do not produce tear while crying. Actually, I have found this true.

Now, I am wondering why is it so? Does any one know the reason behind this?

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See my comment here: biology.stackexchange.com/questions/2087/… Seems to be related to insufficient development of their nervous control (at least according to Wikipedia) –  nico May 5 '12 at 11:07

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It is not completely true. Babies develop the lacrimal system at 42 days, in utero. The canals and ducts for tears are formed at 60 days [2].

At birth, tear production by the lacrimal gland is minimal. Normal tearing develops several days to 2 weeks after birth.[1]

Some 6% of newborns are born with a tear duct obstruction (in some online articles it stated up to 10%, but I think my source is more reliable). The child still produces tears, but they can well up on the eyelid [2].

Other more serious abnormalities can cause this problem. Duct cysts or hemangiomas can also cause tear duct blockages in more severe cases. Various factors, such as anatomical abnormalities and problems with pumping tears increase the propensity for the disorder in children with Trisomy-21 [2]. As nico has alluded to in the comments, there may be a lag in the development of the physiology of tear production even in non-Trisomy-21 children.

[1] Thomas K. McInerny, MD, FAAP, ed. 2009. American Academy of Pediatrics Textbook of Pediatric Care. Elk Grove Village, IL. American Academy of Pediatrics, p1706.

[2]M. E. Wilson et al. (eds.), Pediatric Ophthalmology, 2009, pp. 276-284. DOI 10.1007/978-3-540-68632-3_1.

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Thanks you. Precise and concise :) –  orion May 5 '12 at 18:04
    
This does not really answer the question of whether newborns cry without weeping. They have a lacrimal system, but that does not mean that 1) it is fully functional and 2) they use it when crying. –  nico May 6 '12 at 7:06
    
@nico I didn't find anything on the nervous control of the ducts other than its pathophysiology in Trisomy-21 patients. The original question did not ask about full functionality, so I made some presumptions based on the fact that no further anatomical development occurred was noted to occur after birth. If you find some information on the neurophysiological development, I look forward to reading it! –  jonsca May 6 '12 at 12:44

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