Functional Morphology of the Spermatogenesis of Gir Bulls

Abstract

The purpose of this study was to evaluate the functional morphology of the spermatogenesis of Gir bulls, with emphasis on the testicular biometry and testicular parenchyma histomorphometry. Testicular fragments from eight Gir bulls were used. The fragments were fixed by tissue perfusion with Karnovsck’s solution, and inclusion was subsequently performed using glycol methacrylate. Histological sections of 4 μm were made and stained with a 1% toluidine blue-sodium borate solution. The mean age of the bulls was 8.0 ± 1.3 years and the mean body weight was 467.5 ± 26.7 kg. Testicular weight was 289.2 ± 30.5 g on average, and the average gonadosomatic index was 0.12% ± 0.02%. The seminiferous tubules, Leydig cells, stroma, and intertubular tissue composed 80.9% ± 1.7%, 5.4% ± 1.3%, 13.7% ± 1.1%, and 19.1% ± 1.7% of the total testicular weight, respectively. The mean length of the seminiferous tubule per gram of testicle was 17 ± 0.8 m. Losses during spermatogonia mitosis averaged 75.5% ± 3.22%, while losses were 30.6% ± 8.17% during the meiotic phase, which resulted in an average total loss of 81.49% ± 2.58% of cells during the entire process of spermatogenesis. The average daily sperm production per gram of parenchyma was 28.0 × 106 cells. It was concluded that the histometric measurements of testicular parameters in the Gir breed are within the averages reported for other zebu cattle breeds.