Relative sizes of some cellular ultrastructural elements

1000 nanometers (nm) = 1 micrometer (µm)
1000 micrometers (µm) = 1 millimeter (mm)

Structure	Thickness, distance, or diameter (nm)
cleft in gap junction	2
microfilaments (actin)	5 - 7
plasma membrane	7 - 8
intermediar filaments (neurofilaments, gliofilaments)	8 - 12
myosin	12 - 15
ribosomes	15 - 25
intercellular clefts in neuropil	about 20
microtubules	20 - 25
glycogen granules	30
synaptic vesicles	40 - 60
periodicity in collagen	50 - 60
dense-cored vesicles	60 - 120
nuclear pores	90
primary lysosomes	100 - 200
centriole	100 - 250
neurosecretory granules	100 - 400
mitochondria	100 - 500
cilia	200 - 400
human hair	70,000