Tear duct
Tear ducts were found between the eyes and the nose, and served the purpose of tear drainage and physiological response of  extreme emotion in most species, otherwise known as crying. 

Artificial tear ducts were included in Soong-type androids. (; )

The tears of female Elasians caused men's hearts to be enslaved if they came in contact with their flesh. ()

In 2370, when Juliana Tainer was found to be a Soong-type android, it was discovered she possessed tear ducts. ()

Klingons were known to lack tear ducts. ()

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Anatomy