Cross section of honey bee sing at the base and at the end of the sting shaft. After Snodgrass (1910, fig. 40A-B) The anatomy of the honey bee,
U. S. Department of Agriculture, Bureau of Entomology, Technical Series
, Volume 18, Washington, DC, p.1-162, (1910)
[1].

Venom is flowing in the poison canal which is located in the centre of the shaft between stylet and two lancets.