Calyx (anatomy) kidney, a conglomeration of two or three minor calyces to form a major calyx, or the Calyx of Held, a particularly large synapse in the mammalian auditory central nervous system, named by H. Held in his 1893 article "Die centrale Gehörleitung", due to its flower-petal-like shape. In male insects, a funnel-shaped expansion of the basal part of the "vas deferens" (part of the seminal duct). Also in entomology, a flattened cap of neuropile in an insect brain (a component of the corpus pedunculatum) and by certain female insects, an expansion of the oviduct into which the ovarioles open. Calyx (anatomy)
Calyx of Held the calyx is not only characteristic, but pragmatic in terms of auditory chronological development. As a synapse, the calyx of Held follows a mechanism similar to other synapses. A thorough description can be found under neurotransmission. Calcium influx for the immature calyx of Held is mediated by N-, P/Q-, and R-type calcium channels; however upon maturation only P/Q-type calcium channels become dominant. Upon calcium influx, the immature calyx of Held is highly reactive due to its small calcium buffer ability – this causes the release of glutamate even at low levels of calcium influx. Within the terminal, as with other