Table 1.

Comparison of synapsin-positive bouton numbers between studies.

	Peng & Yang17	Krofczik et al.8	Wolschin et al.9	Groh et al.10		Muenz et al.11	Sommerlandt et al.15
forager age	unknown	37 days	5 days of foraging	35 days		32 days	unknown
quantification	automated counts			visually guided counts
method	synapsin WM	synapsin thick section	synapsin WM	synapsin WM	serial EM	synapsin WM	synapsin WM
Lip
total #/calyx	0.4 × 104	NA	NA	15.8 × 104	NA	19.1 × 104	15.9 × 104
#/1,000 µm3	1.9	358.7	~40.0*	32.9	24.5	35.6	36.3
volume (µm3)	2.2 × 106	NA	NA	4.7 × 106	NA	5.4 × 106	4.6 × 106
Collar
total #/calyx	1.4 × 104	NA	NA	30.5 × 104†	NA	31.8 × 104†	29.0 × 104†
#/1,000 µm3	2.0	NA	~40.0*	65.9†	47.1†	63.0†	63.8†
volume (µm3)	7.2 × 106	NA	NA	6.5 × 106	NA	6.9 × 106	4.8 × 106†

Counts of synapsin-positive boutons in the mushroom body calyx lip and collar region of Apis mellifera foragers compiled from different studies. The density of boutons per 1,000 µm³ ranged in the (olfactory) lip region between 25 and 36 in visually guided counts from confocal image series or serial 3D electron microscopy analyses, and between 1.9 and 360 in studies using automated counts based on confocal image series. Similar differences between visually guided and automated counts are evident in the (visual) collar region. Whereas automated counts by Peng and Yang¹⁷ are at least ~18 times lower, the study by Krofczik et al.⁸ revealed up to ~10 times higher numbers compared to visually guided counts from confocal image series and serial electron microscopy. EM = electron micrograph, NA = not applicable, WM = whole mount. *lip and collar not differentiated, ^†only dense collar region.