ABSTRACT
To date, sperm morphometric studies have assessed whole sperm populations without considering sperm function. The aim of this study was to evaluate the relationship of sperm membrane and acrosomal integrity with sperm morphometry in liquid semen samples collected from bulls. To this end, sperm morphometry was performed on cryopreserved semen samples from 16 bulls by a combination of fluorescent dyes, including Hoechst 33343, carboxyfluorescein diacetate, and propidium iodide. This allowed discrimination of different subpopulations on the basis of sperm membrane and acrosomal integrity and analysis of the morphometrics of the sperm head, nucleus, and acrosome using a specific plug-in module created on ImageJ. Acrosomal integrity was related to sperm morphometry as the heads of spermatozoa with a damaged acrosome were significantly smaller than those with a normal acrosome (P < 0.001). In the case of spermatozoa with an intact acrosome, those with a damaged plasma membrane had a larger sperm head and acrosome than spermatozoa with an intact plasma membrane (P < 0.001). No significant differences in the sperm head size were observed between sperm subpopulations without an acrosome or in the nuclear sperm morphometry of the different subpopulations. There was a positive correlation between the sperm motility values of the samples and the morphometric parameters for intact spermatozoa. These correlations were particularly strong for the morphometric parameters of the sperm acrosome. We conclude that there are clear differences in the sperm morphometry depending on the status of the sperm membrane and acrosome and this should be considered when performing this kind of analysis.
ABSTRACT
The aim of this study was to compare the sperm nuclear and acrosomal morphometry of three species of domestic artiodactyls; cattle (Bos taurus), sheep (Ovis aries), and pigs (Sus scrofa). Semen smears of twenty ejaculates from each species were fixed and labeled with a propidium iodide-Pisum sativum agglutinin (PI/PSA) combination. Digital images of the sperm nucleus, acrosome, and whole sperm head were captured and analyzed. The use of the PI/PSA combination and CASA-Morph fluorescence-based method allowed the capture, morphometric analysis, and differentiation of most sperm nuclei, acrosomes and whole heads, and the assessment of acrosomal integrity with a high precision in the three species studied. For the size of the head and nuclear area, the relationship between the three species may be summarized as bull > ram > boar. However, for the other morphometric parameters (length, width, and perimeter), there were differences in the relationships between species for sperm nuclei and whole sperm heads. Bull sperm acrosomes were clearly smaller than those in the other species studied and covered a smaller proportion of the sperm head. The acrosomal morphology, small in the bull, large and broad in the sheep, and large, long, and with a pronounced equatorial segment curve in the boar, was species-characteristic. It was concluded that there are clear variations in the size and shape of the sperm head components between the three species studied, the acrosome being the structure showing the most variability, allowing a clear distinction of the spermatozoa of each species.
ABSTRACT
This study was designed to characterize morphometric sperm subpopulations in normozoospermic men by using different statistical methods and examining their suitability to classify correctly different sperm nuclear morphologies present in human ejaculates. Ejaculates from 21 normozoospermic men were collected for the study. After semen collection and analysis, samples were prepared for morphometric determination. At least 200 spermatozoa per sample were assessed for sperm morphometry by computer-assisted sperm morphometry analysis (CASA-Morph) using fluorescence. Clustering and discriminant procedures were performed to identify sperm subpopulations from the morphometric data obtained. Clustering procedures resulted in the classification of spermatozoa into three morphometric subpopulations (large-round 30.4%, small-round 46.6%, and large-elongated 22.9%). In the second analysis, using discriminant methods, the classification was made independently of size and shape. Three morphological categories according to nuclear size (small 13.07 μm2) and four categories were defined on 400 canonical cells (100 × 4) from 10 men according to sperm nuclear shape (oval, pyriform, round, and elongated). Thereafter, the resulting classification functions were used to categorize 4200 spermatozoa from 21 men. Differences in the class distribution were observed among men from both clustering and discriminant procedures. It was concluded that the combination of CASA-Morph fluorescence-based technology with multivariate cluster or discriminant analyses provides new information on the description of different morphometric sperm subpopulations in normal individuals, and that important variations in the distribution of morphometric sperm subpopulations may exist between men, with possible functional implications.