Cryodamage to plasma membrane integrity in head and tail regions of human sperm

Aim: To investigate the effect of cryopreservation on the plasma membrane integrity in the head and tail regions ofindividual sperm, and the relationship between intact cryopreserved sperm and its motility and zona-free hamster oocytepenetration rate. Methods: The eosin Y exclusion and the hypoosmotic swelling tests were combined to form a sin-gle test (HOS-EY test) to identify the spermatozoa with four types of membrane integrity. Results: After cryop-reservation, there was a marked decline in the percentage of spermatozoa with Type Ⅳ membrane integrity (head mem-brane intact/tail membrane intact), and a significant increase in those with Type Ⅰ (head membrane damaged/tail mem-brane damaged) and Type Ⅲ (head membrane damaged/tail membrane intact) membrane integrity (n = 50, P <0.01). The value of Type Ⅲ integrity had a wide range of variability, whereas Type Ⅱ (head membrane intact/tailmembrane damaged) was uncommon after thawing. A high correlation was observed between the percentage of Type Ⅳintegrity and sperm motility ( n = 50, r = 0.74, P < 0.01 ). However, the values of Type Ⅳ integrity were usuallylower than those of post-thaw motility in most cryopreserved samples. The value of Type Ⅳ integrity did not correlatewith the sperm penetration rate ( n = 25, r = 0.22, P > 0.05). Conclusion: (1) The HOS-EY test has the advan-tage of showing four patterns of membrane integrity in individual spermatozoon; (2) Cryopreservation causes a signifi-cant membrane rupture in the head and tail regions of spermatozoa; Type Ⅲ is the main transitional state of membranecryodamage; (3) Cryodamage to head and tail membrane may occur independently; the presence of an intact tail mem-brane does not necessarily indicate the intacmess of head membrane. (4) Intact membranes are closely related to post-thaw motility, but do not reflect the fertilizing potential.

Influence of enterococci on human sperm membrane in vitro

Aim： To study the influence of enterococci on human sperm membrane in vitro. Methods： Ejaculated human sperm were artificially infected with β-hemolytic or non-β-hemolytic enterococci at the bacteria： sperm ratio of 50：1 at 37℃. Sperm membrane integrity was examined after incubation for 1, 3 and 5 h by hypoosmotic swelling （HOS） test and electron microscopy. Results： Sperm infected with β-hemolytic enterococci had lower HOS scores compared with non-β-hemolytic strains or uninfected control （P 〈 0.01）. The HOS test scores of sperm infected with β-hemolytic enterococci increased in the presence of phosphatidylcholine, an inhibitor of hemolysin. Non-β-hemolytic strains showed no significant difference in swelling rate, compared with the control group （P 〉 0.05）. It was shown by electron microscopy that β-hemolytic enterococci caused significant rupture of human sperm membrane. Conclusion： β-hemolytic enterococci caused human sperm membrane injury, and might be mediated by the hemolysin of enterococci.