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Some male birds and mammals congregate in communal courting grounds called leks.
Persian leopard (Panthera pardus ciscaucasica), also called Caucasian leopard
The pancreas. This organ sits just below the stomach and is both an exocrine and an endocrine gland.
Arthroscopic surgery. In this illustration, the knee joint is undergoing surgery with a specialized
Earth’s history is divided into nested sets of time--eons, eras, periods, and epochs--and is called
A lesion called a plaque in the brain of an individual with Alzheimer disease. A ring of degeneratin