Effect of age and season on the establishment of spermatogenesis in the horse.
Abstract: To determine the age at which adult values for hormonal and testicular characteristics are established, testes and blood from 123 slaughtered horses, aged 1-5 years, were compared. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) and intratesticular testosterone (ITT) were determined by radio-immunoassay. Specimens were obtained in the non-breeding (n = 46) or breeding (n = 43) season in Experiment 1 (Exp. 1) and in the breeding (n = 34) season in Experiment 2 (Exp. 2). Testicular parenchyma was fixed in glutaraldehyde and homogenized to enumerate nuclei of Sertoli cells and elongated spermatids. Paired parenchymal weight (PPar-Wt), Sertoli cell number per horse (SC/H) and daily sperm production per gram of parenchyma (DSP/g) or per horse (DSP/H) were determined. In Exp. 1, DSP/g and SC/H were higher (P less than 0.05) in the breeding season. Left (LT-Wt; adult value established at 4 years) and right (RT-Wt; 3 years) testicular weights, PPar-Wt (4 years), DSP/g (3 years), DSP/H (3 years), SC/H (3 years), number of elongated spermatids/SC (ES/SC; 5 years), LH (5 years) and T (5 years) increased (P less than 0.01) with age. FSH also increased (P less than 0.05) with age. Age was correlated (r = 0.47 to 0.72; P less than 0.01) with LT-Wt, RT-Wt, PPar-WT, DSP/g, DSP/H, SC/H, ES/SC, LH and T. DSP/H was correlated (r = 0.40 to 0.94; P less than 0.01) with PPar-Wt, SC/H, ES/SC, LH and T. In Exp. 2, left testes were processed for histology and scored for percentage of tubules with elongated spermatids (% ES) or residual bodies (% RB). LT-Wt (adult value established at 4 years), RT-Wt (4 years), PPar-Wt (4 years), T (4 years), LH (4 years), % ES (2.5 years) and % RB (2.5 years) were influenced (P less than 0.01) by age. Age was correlated (r = 0.41 to 0.84; P less than 0.01) with PPar-Wt, % ES, % RB, LH, T and ITT. Although adult values of % ES, % RB, DSP/g and DSP/H were obtained by Year 3, PPar-Wt and serum hormonal concentrations increased significantly and DSP/H tended to increase to Year 4.
Publication Date: 1991-01-11 PubMed ID: 1795306
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research investigates the age at which horses reach full maturity regarding their reproductive characteristics and hormones. It examines the effects of both age and season on the establishment of spermatogenesis, the process by which spermatozoa are produced.
Objective and Methodology
- This study was to determine the age at which horses achieve adult values for various reproductive hormones and testicular characteristics.
- Horses used for the study were ages 1-5 years, and the researchers collected blood and testes samples.
- The researchers measured serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T).
- The tests were conducted during both breeding (n = 43 and n = 34) and non-breeding (n = 46) seasons in two experiments.
Findings from Experiment 1
- There was an observed higher daily sperm production per gram of parenchyma (DSP/g) and Sertoli cell number per horse (SC/H) during the breeding season.
- Different parameters including left and right testicular weights, and the aforementioned DSP/g and SC/H, among others, increased with age.
- The researchers found a significant correlation between age and all of these parameters.
- Additionally, there was a significant correlation between DSP/H and a number of the parameters including left and right testicular weights, and LH and T hormone levels.
Findings from Experiment 2
- In this experiment, the left testes were processed for histology and analyzed for tubules with elongated spermatids (% ES) or residual bodies (% RB).
- Again, several parameters increased with age, namely left and right testicular weights, LH and T hormones, and the percentage of tubules with elongated spermatids or residual bodies.
- A significant correlation was found between age and these parameters.
Overall Outcome
- It was observed that although adult values of %ES, %RB, DSP/g, and DSP/H were obtained by Year 3, parenchymal weight and serum hormonal concentrations continued to increase significantly, and DSP/H tended to increase until Year 4.
- Therefore, the study concluded that age, more than the season, plays a significant role in the establishment and development of the reproductive maturity of horses.
Cite This Article
APA
Johnson L, Varner DD, Thompson DL.
(1991).
Effect of age and season on the establishment of spermatogenesis in the horse.
J Reprod Fertil Suppl, 44, 87-97.
Publication
Researcher Affiliations
- Department of Veterinary Anatomy, College of Veterinary Medicine, Texas A&M University, College Station 77843.
MeSH Terms
- Age Factors
- Animals
- Follicle Stimulating Hormone / blood
- Horses / blood
- Horses / physiology
- Luteinizing Hormone / blood
- Male
- Seasons
- Sexual Maturation / physiology
- Spermatogenesis / physiology
- Testis / physiology
- Testosterone / blood
Grant Funding
- HD-16773 / NICHD NIH HHS
Citations
This article has been cited 4 times.- Cruz A, Sullivan DB, Doty KF, Hess RA, Canisso IF, Reddi PP. Acrosomal marker SP-10 (gene name Acrv1) for staging of the cycle of seminiferous epithelium in the stallion. Theriogenology 2020 Oct 15;156:214-221.
- Li B, He X, Zhao Y, Bai D, Bou G, Zhang X, Su S, Dao L, Liu R, Wang Y, Manglai D. Identification of piRNAs and piRNA clusters in the testes of the Mongolian horse. Sci Rep 2019 Mar 22;9(1):5022.
- Wang XN, Li ZS, Ren Y, Jiang T, Wang YQ, Chen M, Zhang J, Hao JX, Wang YB, Sha RN, Huang Y, Liu X, Hu JC, Sun GQ, Li HG, Xiong CL, Xie J, Jiang ZM, Cai ZM, Wang J, Wang J, Huff V, Gui YT, Gao F. The Wilms tumor gene, Wt1, is critical for mouse spermatogenesis via regulation of sertoli cell polarity and is associated with non-obstructive azoospermia in humans. PLoS Genet 2013;9(8):e1003645.
- Folgmann MS, Stock KF, Feige K, Delling U. Clinical findings of candidate stallions presented for licensing at all German Warmblood horse-breeding associations in 2018-2020. Equine Vet J 2025 Nov;57(6):1584-1591.
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