Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 9, 2007
Publication Date: June 20, 2007
Citation: Ford, J.J. 2007. Testicular development in meishan and commercial crossbred prepubertal boars [abstract]. Journal of Animal Science. 85 (Supplement 1):651-652. (Abstract #894) Technical Abstract: Total daily sperm production and testicular size of adult boars increase in proportion to the number of Sertoli cells within the testis. Meishan (MS) boars experience puberty at a younger age than commercial crossbred (CB) boars in association with earlier cessation of Sertoli cell proliferation and smaller postpubertal testicular size. The objectives of the current study were 1) to define changes in the production of anti-Mullerian hormone (AMH) and p27kip1, markers of Sertoli cell differentiation, in prepubertal MS and CB boars (n >/= 4/breed/d), and 2) to relate these changes with the pubertal expansion of the seminiferous tubules. Presence of AMH and p27kip1 were assessed by immunohistochemistry and densitometric analyses using a Bioquant Nova color imaging system. Testicular weights were similar (P > 0.10) in MS and CB boars at 7, 28, and 49 d of age although CB boars had greater (P < 0.01) body weight at these ages. Testes weights of MS increased more rapidly than in CB after 49 d of age and were greater (P < 0.02) at 70, 91, and 112 d of age. Diameter of seminiferous tubules increased (P < 0.01) at a younger age and to a greater extent in MS than in CB boars. Relative amount of AMH, a product of less mature Sertoli cells, increased in both breeds from 7 to 28 d. AMH then declined thereafter at a more rapid rate (P < 0.001) in MS than CB boars and was nearly absent at 70 d in MS and at 112 d in CB boars. Seminiferous tubules containing p27kip1 were first detected at 28 d in some MS and at 70 d in some CB boars (P < 0.01) and increased in both breeds through 112 d. The earlier onset of pubertal development in MS boars was characterized with expansion of seminiferous tubules at a younger age in association with a more rapid decline in MIH production and an earlier increase in p27kip1, indicative of an earlier onset of Sertoli cell differentiation in MS relative to CB boars.