Pintus Eliana, Kotrba Radim, Ros-Santaella José Luis
Department of Veterinary Sciences, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia.
Department of Animal Science and Food Processing, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Prague, Czechia.
Front Cell Dev Biol. 2024 Aug 20;12:1421634. doi: 10.3389/fcell.2024.1421634. eCollection 2024.
In polygynous species, the development of secondary sexual characters is usually decisive for male reproductive success. However, our understanding about the links between the growth of these traits and reproductive efficiency is still elusive. Most research efforts in this topic have been also focused on adult males, although the development of some secondary sexual characters, like bovid horns, typically starts after birth, continues during the puberty and in some species, such as the common eland, slows or even stops during adulthood. In this study, we investigated the relationships between horn size and testicular function during sexual development in common elands using a comprehensive approach that considers both spermatogenic and sperm parameters. Twenty-two non-sexually mature common elands were used for the present study. Horn size, body mass, testes mass, and gonadosomatic index were assessed. Spermatogenic activity was determined by cytological and histological analyses. Sperm concentration, morphology, morphometry, and intramale variation in sperm size were evaluated on epididymal sperm samples. Cluster analysis was performed to explore the influence of age on relationships between horn size and reproductive function. We found that bigger horns are associated with increased Sertoli cell efficiency and reduced intramale variation in sperm size. Both parameters were not related to one another while they have shown to be associated with enhanced sperm quality in ungulates. Moreover, horn size was positively linked to the testis mass, sperm concentration, and testicular investment in the seminiferous epithelium. Spiral length and basal circumference were the horn traits most strongly correlated with spermatogenic and sperm parameters as well as those responsible for the sexual dimorphism in this species. Cluster analysis rendered two groups: the first one including males ≤30 months old, while the second one those >30 months old. Horn development and reproductive function were still correlated within age groups, with the strongest relationship found between horn size and sperm size homogeneity in males >30 months old. Taken together, our results indicate that horn size can be regarded as a good index of male reproductive potential during sexual development and provide insights into the role of secondary sexual characters in sexual selection dynamics.
在一夫多妻制物种中，第二性征的发育通常对雄性繁殖成功起决定性作用。然而，我们对这些特征的生长与繁殖效率之间联系的理解仍然很模糊。尽管某些第二性征（如牛科动物的角）的发育通常在出生后开始，在青春期持续，并且在一些物种（如大羚羊）中，在成年期会减缓甚至停止，但该主题的大多数研究工作也都集中在成年雄性身上。在本研究中，我们采用一种综合方法，考虑生精和精子参数，研究了大羚羊性发育过程中角大小与睾丸功能之间的关系。本研究使用了22只未性成熟的大羚羊。评估了角大小、体重、睾丸重量和性腺体指数。通过细胞学和组织学分析确定生精活性。对附睾精子样本评估精子浓度、形态、形态测量以及精子大小的雄性个体内变异。进行聚类分析以探讨年龄对角大小与生殖功能之间关系的影响。我们发现，较大的角与支持细胞效率提高和精子大小的雄性个体内变异减少有关。这两个参数彼此不相关，但它们已被证明与有蹄类动物精子质量的提高有关。此外，角大小与睾丸重量、精子浓度以及睾丸对生精上皮的投入呈正相关。螺旋长度和基部周长是与生精和精子参数以及该物种性二态性最密切相关的角特征。聚类分析产生了两组：第一组包括年龄≤30个月的雄性，而第二组包括年龄>30个月的雄性。角发育和生殖功能在年龄组内仍然相关，在年龄>30个月的雄性中，角大小与精子大小同质性之间的关系最为密切。综上所述，我们的结果表明，角大小可被视为性发育过程中雄性繁殖潜力的良好指标，并为第二性征在性选择动态中的作用提供了见解。
