Acrosomal function of human spermatozoa with normal and abnormal head morphology

Abstract

In previous studies we have shown differences in the function of morphologically normal and abnormal sperm by evaluating their flagellar movements and swimming trajectories. In this study we have compared the capability of morphologically normal and abnormal human sperm to undergo an acrosome reaction after incubation with human follicular fluid. Semen samples were studied from 6 research donors and 21 semen evaluation patients. All men had normal semen by clinical criteria. Semen was prepared either by a two-step Percoll gradient centrifugation or the sperm were diluted, washed, and centrifuged three times. Sperm suspensions were incubated for 24 hours in a modified Tyrode's medium, containing 2.6% bovine serum albumin, prior to dilution with human follicular fluid. The percentage of acrosome reactions among viable sperm was assessed after 15 minutes using the supravital Hoescht stain and fluoresceinated pea lectin. Sperm head size was measured with an ocular micrometer and normal values were defined as length 3-5 microns and width 2-3 microns. At least 25 viable normal sperm, and 25 viable abnormal sperm were analyzed for acrosome reactions on each slide. With Percoll separation the percentage of acrosome reactions (mean +/- sem) for normal sperm was 38 +/- 3% vs. 22 +/- 2% for abnormal sperm (P less than 0.005). After washing, the comparable values were 12 +/- 1% vs. 5 +/- 1% (P less than 0.005). The incidence of spontaneous acrosome reactions (24 hours of incubation, no follicular fluid) was also higher for normal sperm than abnormal sperm (9 +/- 1% vs. 4 +/- 1%, P less than 0.01). These data demonstrate an association between normal sperm morphology and acrosomal function.

The Human Sperm Head: A Key for Successful Fertilization

“…In our cohort, the increase in the proportion of sperm with specific head shapes had an influential effect on the rates of AR, with the rate being positively correlated to those sperm with normal (oval) heads. These findings are in agreement with the results of Fukuda et al (1989), who reported that morphologically abnormal sperm had lower rates of acrosomal loss after incubation with FF than normal sperm.…”

Cryopreservation of spermatozoa from wild-born Namibian cheetahs (Acinonyx jubatus) and influence of glycerol on cryosurvival

“…Based on the decline in acrosomal integrity following dilution of the cryoprotectant and centrifugation, it appeared that cheetah spermatozoa were susceptible to both osmotic damage and centrifugal forces. It has been previously reported that the proportion of structurally normal spermatozoa in a raw ejaculate may be directly related to overall sperm function due to a negative association between abnormal sperm morphology and acrosomal function [6]. Indeed, there was a strong positive correlation between the percentage of normal spermatozoa and the proportion of these cells with intact acrosomal membranes in raw ejaculates.…”

Multiple roles for the actin cytoskeleton during regulated exocytosis

“…In endothelial or alveolar type II cells, molecules such as the von-Willebrand factor (50–20000 kDa) and the surfactant are densely packed in cigar shaped Weibel-Palade bodies (0.5 × 1.5 μm) and lamellar bodies respectively (diameter 1.5–2 μm). Finally, a peculiar case is sperm where a complex mixture of proteins needed for fertilization such as hyaluronidase and acrosin, are released from the acrosome, a large single cup shaped organelle that can reach a few microns in size [67]. …”