Postnatal somatic cell proliferation and seminiferous tubule maturation in pigs: A non-random event

Avelar, Gleide F.; Oliveira, Carolina F.A.; Soares, Jaqueline M.; Silva, Israel J.; Dobrinski, Ina; Hess, Rex A.; França, Luiz R.

doi:10.1016/j.theriogenology.2009.12.014

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Volume 74, Issue 1 , Pages 11-23, 1 July 2010

Postnatal somatic cell proliferation and seminiferous tubule maturation in pigs: A non-random event

Gleide F. Avelar
- Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 31270-901
Carolina F.A. Oliveira
- Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 31270-901
Jaqueline M. Soares
- Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 31270-901
Israel J. Silva
- School of Veterinary Medicine, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 31270-901
Ina Dobrinski
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
Rex A. Hess
- Department of Veterinary Biosciences, University of Illinois, Urbana-Champaign, IL, USA
Luiz R. França
- Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 31270-901
- Corresponding author. Tel.: +55 31 34092816; fax: +55 31 34092780.

Received 30 October 2009; received in revised form 9 December 2009; accepted 17 December 2009. published online 02 March 2010.

Abstract

Although seminiferous tubule maturation in horses begins in the central area of the testis, this process is thought to occur randomly throughout the testis in most mammals. Studies in our laboratory revealed that the establishment of spermatogenesis may not be a synchronous event in the testicular parenchyma of pigs. The objectives of the present study were to evaluate the pattern of seminiferous cord/tubule maturation and the morphological and functional characteristics of testicular somatic cells during postnatal development in three regions of the pig testis: a) near the tunica albuginea (TA); b) in the transitional area between the seminiferous tubules and mediastinum (TR); and c) in the intermediate area (ID) between the TA and TR. Based on the diameter of seminiferous cords/tubules, nucleus size of Sertoli cells and fluid secretion, mainly at 90 and 120 d of age, seminiferous tubule maturation was more advanced in the ID and TR. The mitotic activity of Sertoli cells was higher (P<0.05) in the TR than the ID and TA at 7 and 120 d. Except for the mitotic index of the Leydig cells, which was lower (P<0.05) in the ID at 7, 30, and 180 d than in the TA and TR, other Leydig cell ebd points, e.g., individual cell size, nuclear volume, and cytoplasmic volume, were consistently higher (P<0.05) in the ID, suggesting that steroidogenesis was more active in this region during the period investigated. Overall, we inferred that Leydig cells in the ID may play a pivotal role in postnatal testis development in pigs and this type of cell is likely related to asynchronous testicular parenchyma development, with the transitional area providing the primary zone for growth of seminiferous tubules.