Spermatogenesis, seminal characteristics and reproductive hormone levels in mature rams with induced @entity1375 and XXXX .

@entity1 @entity1375 @entity251 @entity4396 @entity1378 @entity72897 @entity342 @entity1319
Mature Merino rams were made @entity1375 by daily oral drenching with @entity72897 or @entity1378 by daily subcutaneous injections of thyroxine for 8 weeks. Neither @entity1375 nor @entity1378 had any apparent effect on either spermatogenesis or daily sperm production, but motility of ejaculated spermatozoa and circulating @entity251 concentrations were reduced in both conditions. The ratio of @entity251 concentrations in plasma from the internal spermatic vein to those in peripheral blood plasma was higher in @entity1378 (21.2 +/- 3.5) than in control (11.1 +/- 4.4) and @entity1375 (7.6 +/- 1.4) rams. The basal secretion rate for @entity251 was slightly lower in @entity1375 rams and @entity251 responses to @entity1 chorionic gonadotrophin and after @entity4396 ( @entity4396 ) were very much reduced. Basal serum LH levels were low in both @entity1375 and @entity1378 rams compared with controls whereas there were no differences in FSH levels. The LH response to exogenous @entity4396 was reduced in @entity1375 rams but not in @entity1378 rams. Serum prolactin levels on the other hand were higher than control in both @entity1375 and @entity1378 rams. Reduced @entity251 secretion in @entity1375 rams indicates that the normal function of Leydig cells depends on an adequate level of thyroid hormones. The decrease in circulating @entity251 concentrations in @entity1378 rams with normal secretion rates suggests an increased @entity251 clearance rate in these animals. The @entity1319 in hypo- and @entity1378 rams suggests that the lowered @entity251 level in these animals has altered the @entity342 -dependent maturation of spermatozoa in the epididymis.(ABSTRACT TRUNCATED AT 250 WORDS)
