Ocellar projections within the central nervous system of the worker honey bee, Apis mellifera

The projections of ocellar fibres within the brain and thorax of the honey bee, Apis mellifera, were established using a modified cobalt sulphide technique, supplemented by serial sectioning of the brain for the light microscope. The results are: 5 large fibres in each lateral nerve and 12 in the median nerve have wide-field terminal arborisations in ocellar association areas on either side of the posterior slope area. 9 medium-sized fibres in each lateral nerve and 12 in the median nerve form a second ocellar association area on each side of the perioesophageal foramen. A group of fine fibres , stained via the ocellar nerves, arborise just below and anterior to the protocerebral bridge. 10 medium-sized fibres run from the level of the ocellar nerve tracts to the first and second thoracic ganglia, branching in a number of discrete areas within each ganglion. These fibres also form a restricted ocellar association area within the suboesophageal ganglion. A few fibres run between the higher-order optic centres and the ocellar tract. The large- and medium-sized fibres give off short, stout spines from their axons within the ocellar tracts.