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Geometric morphometrics of rodent sperm head shape.

Varea Sánchez M, Bastir M, Roldan ER - PLoS ONE (2013)

Bottom Line: Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge.Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa.It is also capable of discriminating between size and shape and to analyze these two variables separately.

View Article: PubMed Central - PubMed

Affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

ABSTRACT
Mammalian spermatozoa, particularly those of rodent species, are extremely complex cells and differ greatly in form and dimensions. Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge. No consensus exists on a method to objectively assess size and shape of spermatozoa. In this study we apply the principles of geometric morphometrics to analyze rodent sperm head morphology and compare them with two traditional morphometry methods, that is, measurements of linear dimensions and dimensions-derived parameters calculated using formulae employed in sperm morphometry assessments. Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa. It is also capable of discriminating between size and shape and to analyze these two variables separately. Thus, it provides an accurate method to assess sperm head shape. Furthermore, it can identify which sperm morphology traits differ between species, such as the protrusion or retraction of the base of the head, the orientation and relative position of the site of flagellum insertion, the degree of curvature of the hook, and other distinct anatomical features and appendices. We envisage that the use of geometric morphometrics may have a major impact on future studies focused on the characterization of sperm head formation, diversity of sperm head shape among species (and underlying evolutionary forces), the effects of reprotoxicants on changes in cell shape, and phenotyping of genetically-modified individuals.

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Sperm head mean deformation patterns after standardization to common regularity.TPS deformation grids illustrate mean shape differences by deforming one species average into that of another species. AS, Arvicola sapidus; AT, Arvicola terrestris; CG, Clethrionomys glareolus and MA, Microtus arvalis.
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pone-0080607-g005: Sperm head mean deformation patterns after standardization to common regularity.TPS deformation grids illustrate mean shape differences by deforming one species average into that of another species. AS, Arvicola sapidus; AT, Arvicola terrestris; CG, Clethrionomys glareolus and MA, Microtus arvalis.

Mentions: We examined mean shape differences after standardization to common values of regularity (Fig. 5); regularity was chosen for this analysis because it was the dimensions-derived parameter that better described shape (although its relation with shape coordinates was limited; see above). Shape differences between species (which were statistically significant) were mainly related to four regions: the point of inflexion of the ventral side of the head (defined by landmark 10), the area of dorsal curvature defined by landmarks 4, 5 and 6, the insertion point of the flagellum, and hook shape and curvature.


Geometric morphometrics of rodent sperm head shape.

Varea Sánchez M, Bastir M, Roldan ER - PLoS ONE (2013)

Sperm head mean deformation patterns after standardization to common regularity.TPS deformation grids illustrate mean shape differences by deforming one species average into that of another species. AS, Arvicola sapidus; AT, Arvicola terrestris; CG, Clethrionomys glareolus and MA, Microtus arvalis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842927&req=5

pone-0080607-g005: Sperm head mean deformation patterns after standardization to common regularity.TPS deformation grids illustrate mean shape differences by deforming one species average into that of another species. AS, Arvicola sapidus; AT, Arvicola terrestris; CG, Clethrionomys glareolus and MA, Microtus arvalis.
Mentions: We examined mean shape differences after standardization to common values of regularity (Fig. 5); regularity was chosen for this analysis because it was the dimensions-derived parameter that better described shape (although its relation with shape coordinates was limited; see above). Shape differences between species (which were statistically significant) were mainly related to four regions: the point of inflexion of the ventral side of the head (defined by landmark 10), the area of dorsal curvature defined by landmarks 4, 5 and 6, the insertion point of the flagellum, and hook shape and curvature.

Bottom Line: Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge.Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa.It is also capable of discriminating between size and shape and to analyze these two variables separately.

View Article: PubMed Central - PubMed

Affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

ABSTRACT
Mammalian spermatozoa, particularly those of rodent species, are extremely complex cells and differ greatly in form and dimensions. Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge. No consensus exists on a method to objectively assess size and shape of spermatozoa. In this study we apply the principles of geometric morphometrics to analyze rodent sperm head morphology and compare them with two traditional morphometry methods, that is, measurements of linear dimensions and dimensions-derived parameters calculated using formulae employed in sperm morphometry assessments. Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa. It is also capable of discriminating between size and shape and to analyze these two variables separately. Thus, it provides an accurate method to assess sperm head shape. Furthermore, it can identify which sperm morphology traits differ between species, such as the protrusion or retraction of the base of the head, the orientation and relative position of the site of flagellum insertion, the degree of curvature of the hook, and other distinct anatomical features and appendices. We envisage that the use of geometric morphometrics may have a major impact on future studies focused on the characterization of sperm head formation, diversity of sperm head shape among species (and underlying evolutionary forces), the effects of reprotoxicants on changes in cell shape, and phenotyping of genetically-modified individuals.

Show MeSH
Related in: MedlinePlus