Follicle profile and plasma gonadotropin concentration in pubertal female ponies
Braz. j. med. biol. res
;
37(6): 913-922, Jun. 2004. tab, graf
Article
in English
| LILACS
| ID: lil-359902
RESUMO
Twelve female ponies were examined daily for 30 days and classified as ovulating (OV; N = 6; 197 ñ 6 kg) or prepubertal (PP; N = 6; 196 ñ 9 kg). Follicles were detected by ultrasound and gonadotropins quantified by radioimmunoassay. The mean diameter of the largest follicles was significantly larger in OV (38 ñ 1 mm) than in PP (26 ñ 2 mm) but there was no difference between groups in the size of the second largest follicle. There were more small follicles (<24 mm) in the PP than in the OV group, but PP fillies had a smaller number of follicles >29 mm than the OV fillies. Follicle-stimulating hormone (FSH) levels did not differ between groups but PP fillies had lower luteinizing hormone (LH) peak (8 ñ 1 ng/ml) and basal (4 ñ 0.5 ng/ml) levels, lower peak magnitude (2 ñ 0.2 ng/ml) and period average (5 ñ 0.6 ng/ml) than OV fillies (32 ñ 4.5, 8 ñ 1.2, 17.1 ñ 6, and 15 ñ 2.3 ng/ml, respectively). The PP group, in contrast to the OV group, showed no relationship between FSH surge and follicle wave emergence. We conclude that an LH concentration higher than 8 ng/ml is needed for follicle growth to a preovulatory size. Wave emergence and FSH secretion seem to be independent events, probably due to an inhibitory neural system in these PP animals. PP fillies may provide a physiological model for the study of follicle wave emergence which apparently does not depend on gonadotropin levels.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Sexual Maturation
/
Luteinizing Hormone
/
Follicle Stimulating Hormone
/
Ovarian Follicle
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2004
Type:
Article
/
Congress and conference
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Estadual Paulista/BR
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