Seasonal variation in sperm freezability associated with changes in testicular germinal epithelium in domestic (Ovis aries) and wild (Ovis musimon) sheep
Lucía Martínez-Fresneda A B C , Emma O’Brien A , Rosario Velázquez A , Adolfo Toledano-Díaz A , Carlos M. Martínez-Cáceres D , Dawit Tesfaye B , Karl Schellander B , Francisco A. García-Vázquez
C E and Julian Santiago-Moreno A F
+ Author Affiliations
- Author Affiliations
A Department of Animal Reproduction, Spanish National Institute for Agricultural and Food Research and Technology (INIA), Avda. Puerta de Hierro km 5.9, 28040 Madrid, Spain.
B Department of Animal Breeding and Husbandry, Institute of Animal Science, University of Bonn, Endenicher Allee 15, 53115 Bonn, Germany.
C Department of Physiology, Faculty of Veterinary Science, International Excellence Campus for Higher Education and Research ‘Campus Mare Nostrum’, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
D Pathology Unit, Biomedical Research Institute of Murcia (IMIB-Arrixaca), Crta. Buenavista s/n, El Palmar 30120 Murcia, Spain.
E Reproductive Physiology and Assisted Reproduction Unit, Biomedical Research Institute of Murcia (IMIB-Arrixaca), Crta. Buenavista s/n, El Palmar 30120 Murcia, Spain.
F Corresponding author. Email: moreno@inia.es
Reproduction, Fertility and Development 31(10) 1545-1557 https://doi.org/10.1071/RD18511
Submitted: 12 December 2018 Accepted: 4 May 2019 Published: 11 June 2019
Abstract
The aim of this study was to examine ovine sperm cryoresistance during the rutting season (RS) and its association with sperm head area and seminiferous epithelium proliferation. Small ruminants show fluctuating testosterone levels throughout the year, which could interfere with spermatogenesis and sperm cryopreservation. Ejaculates, testicular biopsies and blood were collected during the middle and at the end of the RS (Middle-RS vs End-RS) during periods of high and low testosterone levels in Merino and Mouflon rams. Fresh and frozen–thawed sperm quality, sperm morphometry, seminiferous tubule morphometry and testicular proliferation markers (proliferating cell nuclear antigen, proliferation marker protein Ki-67 and transcription factor GATA-4) were evaluated. Post-thaw sperm viability was higher in the End-RS group in both Merino (69.9 ± 8.2 vs 41.6 ± 7.3%; P = 0.020) and Mouflon rams (40.9 ± 3.3 vs 24.2 ± 5.0%; P = 0.008). Mouflons had larger sperm head area at the End-RS (38.3 ± 0.2 vs 34.3 ± 0.1 µm2; P = 0.029), whereas there was no difference between Merino groups (35.7 ± 0.5 vs 34.8 ± 1.0 µm2). Seminiferous tubule morphometry and proliferation markers showed higher levels of germinal epithelium proliferation in the Middle-RS of both species. In conclusion, sperm freezability is affected during the RS in domestic and wild rams, which could be correlated with changes that occur during spermatogenesis, since there is an effect of season on cell proliferation in the testis.
Additional keywords: cryopreservation, Sertoli cell, spermatogenesis, spermatozoa, testis, testosterone.
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