Table 1.

Electron Microscopic Findings in Primary Ciliary Dyskinesia Versus Acquired Cilia Abnormality

	PCD	Acquired defects
EM ultrastructure	Dynein arm deficiency	Compound cilia
	Outer arms	Added peripheral tubules
	Inner arms	Deleted peripheral tubules
	Both	Added central pairs
	Translocation of central tubules	Translocation of central tubules
	Aplasia (generalized)	Aplasia (patchy)
Beat Frequency	Slow or absent	May be normal or reduced
Wave form	Abnormal	May be normal or abnormal

EM, electron microscopy; PCD, primary ciliary dyskinesia.