Fine Surface Structure of Bovine Acrosome-Intact and Reacted Spermatozoa Observed by Atomic Force Microscopy

Abstract

Abstract. The atomic force microscope (AFM) provides nanometer resolution, topographic data of the natural surface structure of materials. We studied the topology of the surface structure of bovine sperm heads during the acrosome reaction by AFM. In addition, we numerically analyzed the areas of the median sagittal plane of the sperm heads. Bovine frozen-thawed spermatozoa were washed, capacitated by heparin, and incubated with lysophosphatidylcholine (LPC) to induce the acrosome reaction, smeared on a cover glass, air-dried, and observed with AFM using the dynamic force (tapping) mode. AFM analysis of spermatozoa showed the clear surface structure of acrosomes, equatorial segments, postacrosomal regions and necks. Although AFM images of spermatozoa capacitated by heparin had complete acrosomes, most spermatozoa treated with LPC had no acrosomal caps as shown by AFM. These observations coincided with those obtained by light microscopy after staining with naphthol yellow S and erythrosin B. Furthermore, numerical analysis of AFM images indicated that areas of the median sagittal plane of the anterior portions of acrosomereacted sperm heads (2679 ± 616 pixels) were approximately 40% less than those of intact heads (4535 ± 174 pixels, P<0.05). These results indicate that AFM can usefully observe and numerically analyze the fine surface structures of bovine spermatozoa.

Nanoscale Differences in the Shape and Size of X and Y Chromosome-Bearing Bovine Sperm Heads Assessed by Atomic Force Microscopy

“…Studies using AFM images identified differences between sperm with intact acrosome and reacted acrosome [20], [21]. The area of the anterior portion of the sperm head with reacted acrosome was approximately 40% smaller than that of sperm with intact acrosome [21].…”

AFM characterization of rabbit spermatozoa

“…For comparison, the head of human sperm imaged by AFM looks almost circular with longitudinal and transverse profiles of about 5.2 and 4.1 lm, respectively (Joshi et al 2001b). AFM images show that the head of bovine spermatozoa is 9 lm long, 4 lm wide, and 0.4 lm thick (Saeki et al, 2005).…”

“…In this respect, AFM is the only technique capable of imaging the surface of living cells at nanometer scale almost in real time (Berdyyeva et al, 2005;Jalili and Laxminarayana, 2004;Shao et al, 1996) without the need for special sample preparation and/or fixation. AFM has been applied for determining the structural and topological features of human (Joshi et al, 2000;Joshi et al, 2001a,b;Kumar et al, 2005Kumar et al, , 2006, bovine, ram, boar, goat, and mouse (Allen et al, 1995;Ellis et al, 2002;Saeki et al, 2005) spermatozoa.…”

Atomic force microscopy: a powerful tool for high-resolution imaging of spermatozoa

“…A more recent study by Takano et al (2004) provides the details of surface structure changes in spermatozoa from mouse epididymis associated with maturation [13]. Saeki et al (2004) have provided similar details about sperm head including acrosome, equatorial segment, post acrosomal region and neck during acrosome reaction induced by lysophosphatidylcholine are given [14]. In addition, a numerical analysis carried out by the research group indicates that the area of medial sagittal plane of the anterior portions of acrosome-reacted sperm heads is approximately 40% less than those of intact heads.…”