<P> As noted above, epithelial sodium channels ENaC that are expressed along the length of cilia regulate fluid level surrounding the cilia . Mutations that decrease the activity of ENaC result in multisystem pseudohypoaldosteronism, that is associated with fertility problems . In cystic fibrosis that results from mutations in the chloride channel CFTR, ENaC activity is enhanced leading to a severe reduction of the fluid level that causes complications and infections in the respiratory airways . </P> <P> Since the flagellum of human sperm is actually a modified cilium, ciliary dysfunction can also be responsible for male infertility . </P> <P> Of interest, there is an association of primary ciliary dyskinesia with left - right anatomic abnormalities such as situs inversus (a combination of findings known as Kartagener's syndrome) and other heterotaxic defects . These left - right anatomic abnormalities can also result in congenital heart disease . It has been shown that proper cilial function is responsible for the normal left - right asymmetry in mammals . </P> <P> Recent findings in genetic research have suggested that a large number of genetic disorders, both genetic syndromes and genetic diseases, that were not previously related in the medical literature, may be, in fact, highly related in the root cause of the widely varying set of medical symptoms that are clinically visible in the disorder . These have been grouped as an emerging class of diseases called ciliopathies . The underlying cause may be a dysfunctional molecular mechanism in the primary / immotile cilia, organelles which are present in many diverse cellular types throughout the human body . Cilia defects adversely affect numerous critical developmental signaling pathways essential to cellular development and thus offer a plausible hypothesis for the often multi-symptom nature of a large set of syndromes and diseases . Known ciliopathies include primary ciliary dyskinesia, Bardet - Biedl syndrome, polycystic kidney and liver disease, nephronophthisis, Alstrom syndrome, Meckel - Gruber syndrome, Sensenbrenner syndrome and some forms of retinal degeneration . </P>

Where are cilia and flagella found in a cell