Relationship of sperm plasma membrane andacrosomal integrities with sperm morphometry inBos taurus

To date,sperm morphometric studies have assessed whole sperm populations without considering sperm function.The aim of this study was to evaluate the relati on ship 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 morphometries 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 in tact 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.

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

Sperm quality is evaluated for the calculation of sperm dosage in artificial reproductive programs. The most common parameter used is motility, but morphology has a higher potential as a predictor of genetic quality. Morphometry calculations from CASA-Morph technology improve morphological evaluation and allow mathematical approaches to the problem. Semen from 28 Holstein bulls was collected by artificial vagina, and several ejaculates were studied. After general evaluation, samples were diluted, packaged in 0.25 ml straws, and stored in liquid nitrogen. Two straws per sample were thawed, and slides were processed and stained with Diff-Quik. Samples were analyzed by a CASA-Morph system for eight morphometric parameters. In addition to the ＂classical＂ statistical approach, based on variance analysis （revealing differences between animals, ejaculates, and straws）, principal component （PC） analysis showed that the variables were grouped into PC1, related to size, and PC2 to shape. Subpopulation structure analysis showed four groups, namely, big, small, short, and narrow from their dominant characteristics, representing 31.0%, 27.3%, 24.1%, and 17.7% of the total population, respectively. The distributions varied between animals and ejaculates, but between straws, there were no differences in only four animals. This modern approach of considering an ejaculate sperm population as divided into subpopulations reflecting quantifiable parameters generated by CASA-Morph systems technology opens a new view on sperm function. This is the first study applying this approach to evaluate different ejaculates and straws from the same individual. More work must be done to improve seminal dose calculations in assisted reproductive programs.