Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2008
Publication Date: July 1, 2008
Citation: Ford, J.J., Wise, T.H. 2008. Defined pattern of Sertoli cell differentiation in pubertal porcine testes [abstract]. Journal of Animal Science. 86 (E-Supplement 2):458. (Abstract #TH170). Technical Abstract: Number of Sertoli cells is a primary determinant of mature testicular size and sperm production. In boars, formation of the blood/testis barrier, which occurs by 4 mo of age in commercial breeds, signals the end of Sertoli cell proliferation. Previous studies established that expression of p27Kip1, a cyclin-dependent kinase inhibitor and a marker of Sertoli cell differentiation, was first detected at 70 d of age and by 90 d was apparent in tubules of most boars; however, its pattern of expression did not appear random. To test if Sertoli cells differentiation occurs in a defined pattern, one testis was removed from 25 crossbred boars at 90 d of age. From each testis, 2 aliquots of tissue were taken adjacent to the tunica and 2 other aliquots were sampled near the mediastinum. Tissues were fixed and embedded. Tissue sampled near the tunica was further divided into 2 regions, one < 1.5 mm and the other > 1.5 mm from the tunica. A minimum of 200 tubules from each of the 3 regions/boar was evaluated for tubule diameter and percentage with Sertoli cell nuclei positive for p27Kip1 assessed by immunohistochemistry. Mean diameter of seminiferous tubules increased (P < 0.01) from 75.9 µm near the tunica to 90.2 µm in the mediastinum, and percentage of tubules positive for p27Kip1 was greater (P < 0.001) near the mediastinum than near the tunica. Tubules within the sub-tunica region were intermediate for both of these traits. Presence of p27Kip1 correlated positively (P < 0.01) with mean diameter of tubules within each of the 3 regions. Weight of the second testis at 10 mo of age correlated negatively (P < 0.03) with diameter of tubules within the mediastinum at 90 d of age. These findings establish that differentiation of Sertoli cells progresses from the mediastinum toward the tunica thereby implying that proliferation continues for a longer period at the outer region of the seminiferous tubules. Also, 90-d-old boars with testes containing small diameter tubules have a greater compensatory response to unilateral castration than 90-d-old boars with larger diameter seminiferous tubules.