The visual pathway in sea spiders (Pycnogonida) displays a simple serial layout with similarities to the median eye pathway in horseshoe crabs

Table 3 List of abbreviations used in the study

5HT	5-hydroxytryptamine (serotonin)	NUC	Nuclear staining
AB	Arcuate body	ONV	Optic nerve
ABL	Lower arcuate body layer	ORCO	Orcokinin
ABU	Upper arcuate body layer	PBS	Phosphate-buffered saline
AE	Anterior eye	PBTx	PBS + Triton X-100
AEL	Anterior eye lens	PE	Posterior eye
AF	Autofluorescence	PEL	Posterior eye lens
AMN	Antero-median neuropil	PFA	Paraformaldehyde
AMT	Antero-median tract	PNV	Proboscis nerve
AST	Allatostatin	PROC	Proctolin
BR	Brain	R-cell	Retinula cell
BRN	Central brain neuropil	RT	Room temperature
CENV	(dorsal) cephalon nerve	RTA	R-cell axon (bundle)
CHNV	Celiphore nerve	SC	Soma cortex
CLSM	Confocal laser scan microscopy	SVD	Sub-visual domain
PDL	Dorso-posterior lobe	SW	Sea water
HIS	Histamine	SYN	Synapsin
ir	Immunoreactive	TH	Tyrosine hydroxylase
LO	Lateral sense organ	TUB	Tubulin
LONV	Lateral sense organ nerve	VN	Visual neuropil
LT	Lateral thickening	μCT	Micro-computed X-ray tomography
MIP	Maximum intensity projection

ISSN: 1741-7007