Getty/Jason Hosking. A niche is a term that is used in ecological biology to define an organism's role in an ecosystem. Not only does a niche include the environment a given organism lives in, it also includes the organism's job in that environment.
Perilymph (also known as Cotunnius' liquid, and liquor cotunnii) is an extracellular fluid located within the cochlea (part of the inner ear) in two of its three compartments: the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation (positively charged ion) in perilymph is sodium: The values of sodium and potassium concentration in the perilymph are 138 mM and 6.9 mM, respectively.
A minimum of 10,000 red blood cells/ÂµL is required for ascitic fluid to appear pink, and more than 20,000 red blood cells/ÂµL will produce distinctly blood-tinged fluid. This may result from either a traumatic tap or malignancy. Bloody fluid from a traumatic tap is heterogeneously bloody, and the fluid will clot.