Table 1.

Parameters of the neutral-lipid containing organelles from B. napus tapetum and seed, and lipoprotein particles from human

	Brassica			Human
	Tapetum lipid particles	Tapetum plastids	Seed oil bodies	Intestine chylomicrons
Density, g/cm3	1.05	1.02	0.92	<0.96
Diameter, μm	≈3	≈3	0.65	0.1–1.0
Constituents, % (wt/wt)
Neutral lipids	47	69	94	91
Polar lipids	24	18	2	9
Proteins	28	11	3	1–2

Data on seed oil bodies (1) and human extracellular intestine chylomicrons (30) are those reported earlier. Chylomicrons are the only extracellular lipoprotein particles resembling the intracellular lipid organelles in size; all other lipoprotein particles are too small (<0.1 μm) to make a meaningful comparison.