ULTRASONOGRAPHY OF THE DEVELOPING REPRODUCTIVE-TRACT IN RAM LAMBS - EFFECTS OF A GNRH AGONIST

In spring-born ram lambs, the testes (from 2 wk), prostate and vesicul ar glands (from 4 wk) were examined by ultrasonography every 2 wk up t o 26 wk of age. Image analysis was done (numerical pixel values). Ram lambs were treated with a long acting formulation of a GnRH superagoni st (Leuprolide acetate; 1.5 mg/kg) at 3 and 7 wk of age. In blood samp les taken every 15 min for 8 h, mean serum LH, LH pulse amplitude, and basal and mean serum FSH concentrations were lower at 5 wk of age, an d LH pulse frequency was lower at 15 wk of age in animals given Leupro lide acetate compared with those of the controls. There were no differ ences (P>0.05) in testis, prostate or vesicular gland development betw een treated and control animals, Testicular diameter of the left and r ight testes in transverse and longitudinal planes increased slowly to 8 wk of age, more rapidly to 18 wk of age, then more slowly to 26 wk o f age (P<0.05). Numerical pixel values of testicular images decreased from 2 to 8 wk of age, increased to 22 wk of age and then plateaued. W idth of the prostate increased from 4 to 26 wk of age, but length and width of the vesicular glands increased slowly to 8 wk of age, more ra pidly to 18 wk of age and then plateaued (P<0.05). Numerical pixel val ues for the prostate declined from 4 to 8 wk and for the vesicular gla nds, declined from 4 to 10 wk of age; numerical pixel values increased to 12 wk and then decreased to a nadir at 18 wk, followed by a steady increase to 26 wk of age (P<0.05). We concluded that developmental pa tterns of numerical pixel values of the testes, prostate and vesicular glands in ram lambs reflect stages of development, but treatment with a GnRH superagonist at 3 and 7 weeks of age did not affect growth of testes, vesicular or prostate glands. (C) 1997 by Elsevier Science Inc .