Prepubertal changes in immunoreactive inhibin concentration in blood serum and testicular tissue in Holstein bull calves.
Age-related changes in immunoreactive inhibin (ir-inhibin) levels and the relationship among ir-inhibin, gonadotropins and testosterone were examined in 53 Holstein bull calves from neonates to 8.6 months old. Serum levels of ir-inhibin, luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, as well as ir-inhibin levels in testicular extracts, and testicular sizes were measured. All hormones were measured by specific radioimmunoassays. The concentrations of ir-inhibin in serum and testicular tissue were high in neonatal calves and tended to decrease with age. In contrast, serum concentrations of gonadotropins did not show any age-related changes within the experimental period. Serum testosterone levels and testicular sizes (length, width and weight) were positively correlated with age. Furthermore, a positive immunostaining to antiserum for the inhibin alpha-subunit was immunocytochemically observed only in Sertoli cells of the seminiferous tubules from neonates to calves less than 6 months old. These results indicate that the immature bovine testis produces and secretes high levels of ir-inhibin and that the Sertoli cells are a major source of ir-inhibin in prepubertal bull calves.
Matsuzaki
S
S
Department of Veterinary Anatomy, Obihiro University of Agriculture and Veterinary Medicine, Japan.
Uenoyama
Y
Y
Okuda
K
K
Watanabe
G
G
Kitamura
N
N
Taya
K
K
Cruzana
M B
MB
Yamada
J
J
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle / Q000097:blood / Q000254:growth & development / Q000378:metabolism*; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007150:Immunohistochemistry; D007265:Inhibins / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D012708:Sertoli Cells / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D013739:Testosterone / Q000097:blood*
D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone