Elucidation of the role of LH and FSH during neonatal testicular development and growth in the boar

The aim was to elucidate the role of LH and FSH in testicular development and growth in the neonatal boar. On Day 10 after birth (Day 0 of study), animals were assigned to one of nine groups (n = 6): Group 1, control, no treatment; Group 2, hemicastrated (H); Group 3, H and implanted with GnRH agonist (H + GnRH); Group 4, H + GnRH + FSH 200 μg/kg daily from Days 0 to 14 (D0–14); Group 5, H + GnRH + FSH 400 μg/kg D0–14; Group 6, H + GnRH + FSH 400 μg/kg in PVP D0–14; Group 7, H + GnRH + LH 200 μg/kg D0–14; Group 8, H + GnRH + LH 400 μg/kg D0–14; Group 9, H + GnRH + LH and FSH 200 μg/kg D0–14. The right testis in control and hemicastrated boars was removed on Day 15. Hemicastrated boars had greater (P < 0.05) testicular growth than control boars and testicular growth was prevented in boars treated with GnRH agonist. FSH induced Sertoli cell proliferation but not testicular growth whilst LH induced Leydig cell proliferation and testicular growth was similar to control boars but less than hemicastrated boars. LH + FSH induced similar testicular growth as LH alone and neither LH and/or FSH supported testicular hypertrophy in hemicastrated boars. The findings show conclusively for the first time that LH and FSH respectively induce Leydig cell and Sertoli cell proliferation in the neonatal boar. LH additionally supports a normal increase in testicular size in the neonatal boar.