Head morphology of ram spermatozoa is associated with their ability to migrate in vitro and correlates with fertility
Carmen Martínez-Rodríguez A C , Mercedes Alvarez A B , Elena López-Urueña A B , Susana Gomes-Alves A B , Luis Anel-López A E , Jorge E. Tizado D , Luis Anel A B and Paulino de Paz A C F
+ Author Affiliations
- Author Affiliations
A ITRA-ULE, INDEGSAL, University of León, 24071, León, Spain.
B Animal Reproduction and Obstetrics, University of León, 24071, León, Spain.
C Molecular Biology, University of León, 24071, León, Spain.
D Biodiversity and Environmental Management, University of León, 24071, León, Spain.
E SaBio IREC (CSIC-UCLM-JCCM), Campus Universitario s. n. 02071 Albacete, Spain.
F Corresponding author. Email: ppazc@unileon.es
Reproduction, Fertility and Development 28(11) 1825-1837 https://doi.org/10.1071/RD15022
Submitted: 22 August 2014 Accepted: 26 April 2015 Published: 26 May 2015
Abstract
Fertility is a highly complex biological function that depends on several properties of spermatozoa that are necessary for them to overcome various barriers in the female reproductive tract to reach the fertilisation site. This ability has been evaluated in vitro using cervical mucus migration tests. Head morphology has been widely studied, and various studies have reported correlations between head morphology and motility, fertility and DNA fragmentation. In the present study, we first evaluated the relationship between the ability of ram spermatozoa to overcome the mucus surrogate barrier in an in vitro migration test and sperm head morphology. Sperm motility (determined by computer-aided sperm analysis) and the acrosomal status, viability and mitochondrial status (determined by flow cytometry) of control and migrating spermatozoa were assessed. Principal component analysis and clustering analysis of the values for the morphometric parameters assessed defined three cell subpopulations. One of these subpopulations, namely spermatozoa with a short and wide head, was absent from samples collected after conclusion of the migration test. Second, we evaluated relationships among head morphology characteristics, the ability to penetrate the artificial mucus and fertility. We did not find any correlation between fertility and the number of spermatozoa that migrated, whereas there was a negative correlation between the proportion of spermatozoa with a short and wide head in the fresh sperm sample and fertility. In conclusion, the head morphology of spermatozoa was associated with their ability to overcome a mucus barrier in a migration test, and the relative size of the non-migrating subpopulation was negatively related to male fertility.
Additional keywords: acrosome status, mitochondrial potential, motility, oxidative stress, penetration test, viability.
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