Spermiogram and sperm head morphometry assessed by multivariate cluster analysis results during adolescence (12-18 years) and the effect of varicocele

Abstract

This work evaluates sperm head morphometric characteristics in adolescents from 12 to 18 years of age, and the effect of varicocele. Volunteers between 150 and 224 months of age (mean 191, n = 87), who had reached oigarche by 12 years old, were recruited in the area of Barranquilla, Colombia. Morphometric analysis of sperm heads was performed with principal component (PC) and discriminant analysis. Combining seminal fluid and sperm parameters provided five PCs: two related to sperm morphometry, one to sperm motility, and two to seminal fluid components. Discriminant analysis on the morphometric results of varicocele and nonvaricocele groups did not provide a useful classification matrix. Of the semen-related PCs, the most explanatory (40%) was related to sperm motility. Two PCs, including sperm head elongation and size, were sufficient to evaluate sperm morphometric characteristics. Most of the morphometric variables were correlated with age, with an increase in size and decrease in the elongation of the sperm head. For head size, the entire sperm population could be divided into two morphometric subpopulations, SP1 and SP2, which did not change during adolescence. In general, for varicocele individuals, SP1 had larger and more elongated sperm heads than SP2, which had smaller and more elongated heads than in nonvaricocele men. In summary, sperm head morphometry assessed by CASA-Morph and multivariate cluster analysis provides a better comprehension of the ejaculate structure and possibly sperm function. Morphometric analysis provides much more information than data obtained from conventional semen analysis.

Afterword to Sperm morphometrics today and tomorrow special issue in Asian Journal of Andrology

“…By integrating the original variables according to their coherence in a database into a new complex mathematical variable, clearly defined homogeneous subpopulations of spermatozoa can be defined. In support of the theory above, the papers presented here showed that most of the variance from up to 13 morphometric variables could be explained by only two or three PCs: two in bulls,16 adolescent humans,8 adult human sperm head DNA,9 domestic cats,10 puma,11 roosters, and guinea fowls12 and three PCs in adult human split ejaculate samples 7…”

“…Here, the number of subpopulations ranged from two to five: two (for the X-/Y-bearing bovine sperm heads,15 for large+elongated/small+elongated sperm heads in human adolescents8), three (for large+round/elongated/small spermatozoa in human sperm heads in split ejaculate fractions,7 for elongated+intermediate/large+high acrosome/short+small sperm heads in the puma,11 for small, wide and slightly elliptical/average size, long, narrow and very elliptical/very large, wide and elliptical sperm heads in the rooster12), four (for large/high medium/low medium/small in human sperm head DNA,9 for small/short/large/narrow sperm heads in the bull,14 for shape-related sperm heads in both normo- and terato-zoospermic cats10) to five (for very small, wide, very short and slightly elliptical/small, very short, very wide and slightly elliptical/very large, very wide, short and slightly elliptical/average size, very long, very narrow and very elliptical/average size, long, narrow and elliptical sperm heads in the guinea fowl12). …”

“…This Special Issue on computer-aided sperm morphology assessment comprises four reviews (on sperm transport in mammals,3 the current status of sperm morphometry in mammals4 and birds,5 and the relevant statistical methods to assess the morphometric results6); three clinical research papers (on sperm subpopulations in split ejaculates from adult men with normozoospermia7 and in ejaculates from adolescents with or without varicocoele,8 including the use of computer-assisted sperm analysis in assessing sperm nuclear DNA fragmentation9); and six veterinary research papers on sperm populations in the epididymis (in normozoospermic and teratozoospermic domestic cats10) and in ejaculated spermatozoa (from an endangered puma species,11 roosters and guinea fowls,12 rams, bulls and boars,13 and on cryopreserved bovine semen14). …”

Current perspectives of CASA applications in diverse mammalian spermatozoa

“…There has been a wide application for such subpopulation evaluations in domestic animals, including prediction of ejaculate fertility (for a review, see Yániz et al 2015), post-thaw semen quality (Thurston et al 2001;Peña et al 2005) and correlation with sperm chromatin integrity (Núñez-Martinez et al 2007). Even though it is well known that human spermatozoa are heteromorphous in nature, surprisingly little information is available on morphometry subpopulations in men (Santolaria et al 2016;Vásquez et al 2016). This is probably due to the fact that andrologists primarily focus on percentage normal sperm morphology and the most prevalent sperm abnormalities when evaluating human semen.…”

Morphometry and subpopulation structure of Holstein bull spermatozoa: variations in ejaculates and cryopreservation straws

“…Since then, multivariate analysis has been introduced for the simultaneous consideration of all the parameters, including their relationships 24. During recent decades, new efforts have been made to define the best analytical approaches by using subpopulation analysis25 and morphological sperm subpopulation structure, based on morphometric data, which has been observed in a great variety of species: dogs,2627 boars,2829 bulls,3031 foxes,32 humans,3334 llamas,15 marmosets,35 pumas,36 rabbits,37 rams,383940 red deer,41 and stallions 42…”