Morphometric and kinematic sperm subpopulations in split ejaculates of normozoospermic men

This study was designed to analyze the sperm kinematic and morphometric subpopulations in the different fractions of the ejaculate in normozoospermic men. Ejaculates from eight normozoospermic men were collected by masturbation in three fractions after 3-5 days of sexual abstinence. Analyses of sperm motility by computer-assisted sperm analysis （CASA-Mot）, and of sperm morphometry by computer-assisted sperm morphometry analysis （CASA-Morph） using fluorescence were performed. Clustering and discriminant procedures were performed to identify sperm subpopulations in the kinematic and morphometric data obtained. Clustering procedures resulted in the classification of spermatozoa into three kinematic subpopulations （slow with low ALH [35.6% of all motile spermatozoa], with circular trajectories [32.0%], and rapid with high ALH [32.4%]）, and three morphometric subpopulations （large-round [33.9% of all spermatozoa], elongated [32.0%], and small [34.10%]）. The distribution of kinematic sperm subpopulations was different among ejaculate fractions （P 〈 0.001）, with higher percentages of spermatozoa exhibiting slow movements with low ALH in the second and third portions, and with a more homogeneous distribution of kinematic sperm subpopulations in the first portion. The distribution of morphometric sperm subpopulations was also different among ejaculate fractions （P〈 0.001）, with more elongated spermatozoa in the first, and of small spermatozoa in the third, portion. It is concluded that important variations in the distribution of kinematic and morphometric sperm subpopulations exist between ejaculate fractions, with possible functional implications.

Comparison of different statistical approaches to evaluate morphometric sperm subpopulations in men

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 〈10.90 μm^2, intermediate 10.91-13.07 μm^2, and large 〉13.07 μm^2） 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.