Coiled sperm from infertile patients: characteristics, associated factors and biological implication.
BACKGROUND
There is no systematic study on coiled sperm in semen, although they are commonly observed. This work characterizes coiled sperm in infertile men to understand the clinical implications and investigate the possible cause by osmotic swelling.


METHODS
Coiled sperm in semen from 439 infertile patients were quantified and their ultrastructure examined by electron microscopy. Hypo-osmotic swelling (HOS) and demembranation tests were performed to elucidate the nature of the coiling.


RESULTS
Semen from patients contained overall 3% of sperm with head-in-coil (HIC) and 8% other coiled forms, with 12% of patients having 20% or more such sperm. The percentage of coiled sperm (but not HIC) was correlated with age (R = 0.26, P = 0.003) and the epididymal secretory marker neutral alpha-glucosidase (R = 0.16, P < 0.001), and associated with heavy smoking and varicocele. Electron microscopy revealed coiling of tail filaments within the plasma membrane, resembling HOS. Some seminal coiled sperm and most sperm freshly coiled upon HOS could be opened by demembranation, while those that could not be opened were probably fixed in position by oxidation, which occurred more frequently in patients than semen donors.


CONCLUSIONS
Sperm coiling in semen is common and independent of sperm quantity or hormonal status. Whereas HIC may have a genetic background, other coiled forms may be associated with a hostile endogenous milieu in the epididymis that causes swelling.
Yeung
C H
CH
Centre of Reproductive Medicine and Andrology, University of Münster, Domagkstrasse 11, D48149 Münster, Germany. ChingHei.Yeung@ukmuenster.de
Tüttelmann
F
F
Bergmann
M
M
Nordhoff
V
V
Vorona
E
E
Cooper
Trevor G
TG
D000293:Adolescent; D000328:Adult; D002462:Cell Membrane / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D006728:Hormones / Q000097:blood; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009994:Osmolar Concentration; D009995:Osmosis; D012907:Smoking; D013082:Sperm Tail / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D014463:Ultrasonography; D014646:Varicocele / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
D006728:Hormones