X organ

plural X organs · alternative X-organ

1. biologyA cluster of neurosecretory cells located in the eyestalks of crustaceans; it acts as a primary endocrine center that synthesizes and releases hormones regulating functions like molting and growth.

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   In crustaceans, endocrine functions are closely tied to nervous functions. Nervous tissues that produce and release hormones are called neurosecretory tissues. X-organs are neurosecretory tissues in the eyestalks of crayfish. Associated with each X-organ is a sinus gland that accumulates and releases the secretions of the X-organ. [...] Both the X-organ and the Y-organ control ecdysis. The X-organ produces molt-inhibiting hormone, and the sinus gland releases it.

   2001, Miller-Harley, Zoology Fifth Edition