Morphometric study of the testis in sheep embryos using unbiased design-based stereology |
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Authors: | Javad Sadeghinezhad Zahra Ganji Sirous Sadeghian Chaleshtori Hadis Bojarzadeh Mahdi Aghabalazadeh Asl Ali Bayat Khomejini Ehsan Roominai Mohsen Hosseini Margherita De Silva |
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Institution: | 1. Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran;2. Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran;3. Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Bologna, Italy |
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Abstract: | Sheep have been used as translational models of human postnatal testicular development. However, the morphometric features of the normal developing testis in sheep embryos have not been previously investigated using stereology. The objective of the present work was to establish normal quantitative parameters for fetal testicular tissue components in sheep, using unbiased design-based stereological methods. Twenty-four sheep embryos were divided into four gestational age groups (9–11, 12–14, 15–17 and 18–20 weeks of gestation) on the basis of the embryos’ crown-rump length. Isotropic, systematic uniform random sections of the left testes were obtained by employing the orientator method. Testicular total volume, the absolute and proportional volumes occupied by the seminiferous tubules and interstitial tissue, as well as the seminiferous tubule length, were estimated using the point-counting system and the unbiased counting frame principle. All the parameters, with the exception of the interstitial tissue's fractional volume, gradually increased along with gestational age, with the maximum increase especially seen in the late fetal stages. The proportional volume of the interstitial tissue, on the other hand, showed a decreasing trend along with increasing gestational age. The absolute volume of the testes, of the seminiferous tubules and of the interstitial tissue, and the length of the seminiferous tubules showed a significant (p< 0.05) positive linear correlation with gestational age. Several similarities were observed with human testicular embryogenesis. The stereological data emerging from the present study might prove useful as basic contribution to the fields of andrology and embryology and stimulate further research in these areas. |
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Keywords: | embryo embryogenesis fetus morphometry sheep testis |
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