Item	Specie	Anatomical region	Remarks	Reference
1	Pig/Swine	cardiovascular system	PVs discovered in aorta and coronary artery	[10] 2004
2	Rat	caudal vena cava, PVs inside lymph vessels	D = 52 µm, W = 0.24 mm, N = 13	[11] 2007
3	Mice	inside the inferior vena cava	Histological examination showed compositions of cells and the extracellular matrix of the PVs	[12] 2008
4	Rabbit	caudal vena cava, PVs inside lymph vessels	D = 32 µm, W = 0.519 mm, N = 6.	[13] 2008
5	Rat	small intestines	PVs & PNs form network on the surface of the (exposed) intestines. PV entered adipose tissue	[14] 2009
6	Bovine/Cow	atrium & ventricle	Network of PVs & PNs with D ~ 20 µm were revealed in the heart.	[15] 2011
7	Dog	mesentery surrounding the small intestine	The PVS network was visualized in the stated region with structures similar to that in other animals, with fibrous extracellular matrix surrounding the network. Blood vessels, lymph vessels were present in the same mesentery.	[16] 2011
8	Rat	lateral ventricles and arachnoid space of brain	PVs along blood vessels clearly revealed in brain	[17] 2011
9	Pig	subarachnoid space between pia mater and arachnoid mater	Ds of PVs range from 8 to 20 µm, lengths from 0.95 mm to 35 mm, mainly along spinal cord direction.	[18] 2012
10	Chick	chick embryo	Evidence of formation of the PVS before development of vitelline vessels in Chick Embryos.	[19] 2012
11	Rat	surface of stomach	PVs were found to join the surface of stomach as part of the organ.	[20] 2013
12	Mice	skin	Networks of PVs and PNs were revealed on the surface of and deep below the skin	[21] 2015
13	Human	umbilical cord (UC) of a human placenta	The PVs and PNs are revealed in the connective tissues and blood vessels of the umbilical cord (UC). D = 16 μm, attached to two sinuses, with similar morphology as those of animals. A PV just outside the epithelium of a human UC is shown clearly in (Figure 1 of [22] ). Endothelial cells of PVs were different from that of blood and lymph vessels.	[22] 2014