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Hautmann, Victoria; Reiter, Simon; Zöls, Susanne; Maierl, Johann; Kenngott, Rebecca Anna-Maria (26. July 2018): Histological and immunohistochemical evaluation of the seminiferous epithelium of immunocastrated boars vaccinated with Improvac® at different times of age. 32nd Congress of the European Association of Veterinary Anatomists, 25. - 28. Juli 2018, Hannover, Germany.
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Abstract

Introduction: Immunological castration with Improvac®, a synthetic GnRH-vaccine, leads to a disruption in the hypothalamic-pituitary- gonadal- axis with an inhibited secretion of LH and FSH in the pituitary gland. Thus, steroidogenesis in the Leydig-cells is dramatically reduced. The objective of this study was a histological and immunohistochemical evaluation of the seminiferous epithelium and Leydig cells of 29 slaughtered boars divided into five groups. Materials and Methods: Intact boars (group 1, slaughtered 5–6 months of age) were compared to four different groups vaccinated either at 8/12 weeks (group 2), 12/16 weeks (group 3) or 12/18 weeks of age (group 4, 5). Routine stainings and immunohistochemical investigations (Anti-Vimentin, Anti-K8, Anti-DDX- 4 and Anti-Sox- 9, Anti-Testosterone) were performed to investigate the differentiation of the seminiferous epithelium as well as interstitial Leydig-cells. Results: Intact boars show all germ cell types of spermatogenesis arranged well-ordered in several layers in the tubuli seminiferi contorti. Most vaccinated animals have smaller-sized tubuli with a mild to severe disruption in the seminiferous epithelium. Leydig cells show shrunken or pyknotic nucleoli. Interestingly, tubuli with a distinct loss of germ cells showed increased Sertoli cell numbers with an altered round and oval shape arranged closely to each other. There are only few altered and big-sized spermatogonia (no similarity to differentiated spermatogonia) located between Sertoli-cells. Additionally, only few germ cells (mostly spermatocytes) are in the lumen. Vaccinated animals showed small-sized (probably differentiated) spermatogonia, increased germ cell numbers and normal pear-shaped Sertoli cells. DDX-4 could be detected in all germ cells except elongated spermatids. Vimentin and Sox-9 show a positive reaction in Sertoli cells. Conclusion: As immunological vaccination against GnRH influences the seminiferous epithelium as well as Leydig cells in the interstitial tissue at different times of vaccination additional electron microscopic evaluations are necessary to gain further knowledge about changes in testicular cell structure.