[Identification of neurosecretory reservoirs in the mayfly Ephemera danica Müll. (ephemeroptera: ephemeridae) (author's transl)].

Neurosecretory reservoirs were found in the head of Ephemera danica. In the region where the nervus corporis cardiaci 1 is leaving the brain, the diameter of this nerve increases considerably. Different types of axons were observed, filled with great amounts of electron opaque secretory granules with mean diameters of 170 nm and 110 nm, respectively. Another neurosecretory reservoir is situated in the rostral part of the corpus cardiacum containing a secretory material of a different kind. Most of the granules have diameters of about 90 nm, and are electron opaque. A relatively small number of axons contains nearly electron lucent vesicles with the same mean diameter.