| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Regular Article |
a Division of Marine Biosciences, Graduate School of Fisheries Science, and
b Field Science Center for Northern Biosphere, Hokkaido University, Hakodate 041-8611, Hokkaido, Japan
ABSTRACT
In higher vertebrates, considerable progress has been made in understanding the endocrine regulation of puberty; however, in teleosts, the regulatory mechanisms of spermatogenesis during the first annual cycle remain unclear. The present study was conducted to understand the regulatory mechanisms of spermatogenesis throughout the different stages of the first spermatogenic cycle and to check the ability of various steroids and hormones to induce in vitro spermatogonial proliferation in Japanese huchen (Hucho perryi ). The results indicate that the serum level of 11-ketotestosterone (11-KT) was positively associated with germ cell type; the level first began to rise with the appearance of late-type B spermatogonia and continued to increase gradually throughout the active spermatogenic stages and spermiogenesis, reaching a peak value 2 wk before spawning, and then declined. During the spermatogenic stages, the serum concentration of 17
,20ß-dihydroxy-4-pregnen-3-one (17,20ß-DP) was undetectable. Only a small peak was detected with the appearance of spermatocytes and spermatids, and at the time of spawning, the level increased dramatically, reaching its maximum value with the onset of milt production. Despite the high variation in serum levels of 17ß-estradiol (E2) both between months and among the individuals, E2 was found during the whole reproductive cycle. From these results, we concluded that 1) 11-KT is necessary for the initiation of spermatogenesis and sperm production, and it probably plays a role in spermiation, 2) 17,20ß-DP is essential for the final maturation stage, could play a significant role in the mitosis phase and meiosis process, and probably participates in the regulation of spawning behavior, and 3) estrogen is an indispensable male hormone that plays a physiological role in some aspects of testicular functions, especially during the mitotic phase. The three steroids were also able to induce DNA synthesis, spermatogonial renewal, and/or spermatogonial proliferation in vitro.
First decision: 16 April 2001.
1 Supported by a doctoral scholarship from the Mission Department of the Ministry of Education, Egypt, and in part by grants-in-aid from the Ministry of Agriculture, Forestry and Fisheries of Japan (BDP-01-1V-2-1), and from The Japan Society for the Promotion of Science.
2 Correspondence. FAX: 81 138 40 5545; takeshi{at}fish.hokudai.ac.jp
This article has been cited by other articles:
|
|
 |
|
  G.-C. Wu, S. Tomy, M. Nakamura, and C.-F. Chang Dual Roles of cyp19a1a in Gonadal Sex Differentiation and Development in the Protandrous Black Porgy, Acanthopagrus schlegeli Biol Reprod, December 1, 2008; 79(6): 1111 - 1120. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Miura, T. Higashino, and T. Miura A Progestin and an Estrogen Regulate Early Stages of Oogenesis in Fish Biol Reprod, November 1, 2007; 77(5): 822 - 828. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Ozaki, M. Higuchi, C. Miura, S. Yamaguchi, Y. Tozawa, and T. Miura Roles of 11{beta}-Hydroxysteroid Dehydrogenase in Fish Spermatogenesis Endocrinology, November 1, 2006; 147(11): 5139 - 5146. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Miura, M. Higuchi, Y. Ozaki, T. Ohta, and C. Miura Progestin is an essential factor for the initiation of the meiosis in spermatogenetic cells of the eel PNAS, May 9, 2006; 103(19): 7333 - 7338. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
