A preliminary experiment regarding the natural induction of gonadal development in female Japanese eels without hormone treatment

2019 ◽  
Vol 50 (12) ◽  
pp. 3749-3754 ◽  
Author(s):  
Naomi Mikawa ◽  
Yoshiaki Yamada ◽  
Noriyuki Horie ◽  
Akihiro Okamura ◽  
Tomoko Utoh ◽  
...  
Keyword(s):  
Hormone Treatment ◽  
Gonadal Development ◽  
Natural Induction

Manipulation of the Seasonal Reproductive Cycle of the Landlocked Atlantic Salmon (Salmo salar) by LHRH Analogues Administered at Various Stages of Gonadal Development

1983 ◽  
Vol 40 (1) ◽  
pp. 61-67 ◽  
Author(s):  
L. W. Crim ◽  
D. M. Evans ◽  
B. H. Vickery
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Reproductive Cycle ◽  
Gonad Development ◽  
Reproductive Development ◽  
Hormone Treatment ◽  
Gonadal Development ◽  
Rapid Phase ◽  
Atlantic Salmon Salmo Salar ◽  
Lhrh Analogues

Pellets designed for continuous, long-term, oligopeptide, hormone delivery were implanted into the adult landlocked Atlantic salmon (Salmo salar) to investigate the effects of LHRH agonist analogue (LHRH-A) upon the reproductive system. Chronic elevations in plasma gonadotropin were observed in experimental fish at a variety of stages of reproductive development. Synthesis of pituitary gonadotropin was also evoked in sexually regressed fish and fish undergoing gonadal recrudescence, but the already elevated level of pituitary GtH observed in prespawning and spawning salmon was not augmented. In prespawning fish, the events of ovulation and spermiation were accelerated by LHRH-A treatment. The LHRH-A hormone treatment also increased milt volume and the duration of spermiation in ripe males. In sexually regressed males LHRH-A treatment did not induce the advanced phases of spermatogenesis but some testicular stimulation was indicated by the presence of increased numbers of B-type spermatogonia and enlargement of the lumen of lobules. The gonadal response to LHRH-A treatment during the rapid phase of gonad recrudescence differed in males and females. Based upon the changes in GSI, the LHRH analogue accelerated vitellogenic development of the ovaries in females; in males, however, the GSI was significantly reduced following LHRH-A administration. Whereas, it seems clear that a long acting preparation containing LHRH-A can be successfully used in prespawning fishes to advance the final events of gonadal maturation and initiate spawning, further studies are necessary to evaluate the potential of LHRH agonists to either stimulate or inhibit the reproductive development of fish at other stages of the seasonal reproductive cycle.Key words: fish, teleosts, landlocked salmon, LHRH analogues, gonadotropic hormone releasing hormones, seasonal reproductive cycle, gonad development, spawning

Should hormone treatment be started early in response to rising PSA levels?

2007 ◽  
Vol 40 (17) ◽  
pp. 9
Author(s):  
E. DAVID CRAWFORD ◽  
DEREK RAGHAVAN
Keyword(s):  
Hormone Treatment

DIHYDROTESTOSTERONE IN ADOLESCENT MALE PLASMA WITH NORMAL AND ABNORMAL GONADAL DEVELOPMENT

1971 ◽  
Vol 68 (1_Supplb) ◽  
pp. S68
Author(s):  
D. Gupta ◽  
Eileen M. McCafferty ◽  
K. Rager ◽  
K. Jendricke ◽  
J. Bierich
Keyword(s):  
Gonadal Development ◽  
Adolescent Male

Postnatal growth rate and gonadal development in circadian tau mutant hamsters reared in constant dim red light

Reproduction ◽  
2000 ◽  
pp. 327-330 ◽  
Author(s):  
RJ Lucas ◽  
JA Stirland ◽  
YN Mohammad ◽  
AS Loudon
Keyword(s):  
Time Course ◽  
Red Light ◽  
Somatic Growth ◽  
Postnatal Growth ◽  
Gonadal Development ◽  
Testicular Development ◽  
Wild Type ◽  
Similar Time ◽  
Syrian Hamsters ◽  
Body Weights

The role of the circadian clock in the reproductive development of Syrian hamsters (Mesocricetus auratus was examined in wild type and circadian tau mutant hamsters reared from birth to 26 weeks of age under constant dim red light. Testis diameter and body weights were determined at weekly intervals in male hamsters from 4 weeks of age. In both genotypes, testicular development, subsequent regression and recrudescence exhibited a similar time course. The age at which animals displayed reproductive photosensitivity, as exhibited by testicular regression, was unrelated to circadian genotype (mean +/- SEM: 54 +/- 3 days for wild type and 59 +/- 5 days for tau mutants). In contrast, our studies revealed a significant impact of the mutation on somatic growth, such that tau mutants weighed 18% less than wild types at the end of the experiment. Our study reveals that the juvenile onset of reproductive photoperiodism in Syrian hamsters is not timed by the circadian system.

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