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

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 <10.90 μm2, intermediate 10.91–13.07 μm2, and large >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.

Toward an integrative and predictive sperm quality analysis in Bos taurus

“…The fluorescent sperm subpopulations described in this paper may have a correspondence with the sperm subpopulations described in different species by applying statistical analysis to the kinematic and morphometric parameters provided by the CASA system (Martinez-Pastor et al, 2005;Nunez Martinez et al, 2006;Dorado et al, 2010;Yániz et al, 2015a;Yániz et al, 2015b;Santolaria et al, 2016;Yániz et al, 2016). The use of these techniques allows classification of the overall sperm population into separate subpopulations, grouping spermatozoa with similar kinematic or morphometric characteristics.…”

Effect of frame rate capture frequency on sperm kinematic parameters and subpopulation structure definition in boars, analysed with aCASA‐Mot system

“…Previously, the whole population of spermatozoa in an ejaculate has been considered; as it was described by a normal distribution model, spermatozoa were considered as equivalent, with the same chances of being “selected” for fertilization. Nevertheless, by considering the quantitative data obtained from CASA systems, different authors have proposed that the actual distribution of sperm cells is not uniform, not normally distributed but structured in well‐defined subpopulations, (Amann & Hammerstedt, ; Caldeira et al., ; Gallego et al., ; Hirai et al., ; Soler et al., ; Thurston, Watson, Mileham, & Holt, ; Valverde et al., ; Vásquez et al., ; Yániz et al., , ). Even today, in the boar, a relationship between these subpopulations and the fertilizing capacity of the ejaculates has been established (Abaigar et al., ; Holt et al., ; Vyt et al., ).…”

“…Another aspect is that the correct determination of sperm tracks results in a fundamental shift in the determination of motility and morphology subpopulation structure. The fact that an ejaculate is constituted of different subpopulations of spermatozoa has been well established in a great variety of species (boar (Abaigar, Holt, Harrison, & del Barrio, ; Flores et al., ; Holt, Holt, & Moore, ; Soler et al., ), bull (Valverde et al., ; Yániz et al., ), donkey (Flores et al., ), eel (Gallego et al., ), fox (Soler et al., , ), gazelle (Abaigar et al., ), goat (Vázquez et al., ), ram (Luna et al., ), stallion (Ortega‐Ferrusola et al., ), human (Vásquez, Soler, Camps, Valverde, & García‐Molina, ; Yániz et al., ), salmon (Caldeira et al., )), but most of these studies were not designed for considering the effect of the FR.…”

Análisis computarizado de semen de camélidos

“…La morfometría de espermatozoide también puede ser empleada en estudios de biología evolutiva (Yániz et al, 2016a), como lo reportaron Sanchez et al, (2012) y Soler et al, (2017 Fragmentación del ADN espermático La integridad del ADN del espermatozoide es un parámetro indicador de la calidad seminal y la fecundidad. Algunos estudios indican que el daño en éste está asociado con anomalías en los parámetros seminales convencionales, la integridad del ADN y la cromatina espermática son esenciales para la correcta transmisión de la información genética a las generaciones futuras (Kodama et al, 1997;Irvine et al, 2000).…”