TY - JOUR
T1 - Diurnal Periodicity in Testicular Activity in the Japanese Flounder Paralichthys olivaceus
AU - Matsuyama, Michiya
AU - Yoneda, Miki
AU - Takeuchi, Hiroyuki
AU - Kawaga, Hirohiko
AU - Kashiwagi, Masaaki
AU - Tabata, Kazuo
AU - Nagahama, Yoshitaka
AU - Ijiri, Shigeho
AU - Adachi, Shinji
AU - Yamauchi, Kohei
PY - 1995/1/1
Y1 - 1995/1/1
N2 - Testicular activity, as represented by the amount of each type of testicular germ cell in the seminal lobules, and the serum levels of three major male teleost steroids—testosterone (T), 11-ketotestosterone (11-KT), and 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP)—were investigated during the daily spawning cycle of the male Japanese flounder Paralichthys olivaceus. B-type spermatogonia and spermatocytes increased in number from the lowest level at 22:00 (186 cells/lobule), and peaked at 10:00 (292 cells/lobule). The number of spermatozoa increased from 14:00 (370cells/lobule) and peaked at 22:00 (782 cells/lobule). In contrast, spermatid numbers decreased from 14:00 (579 cells/lobule) and showed the lowest level at 22:00 (348 cells/lobule). These results indicate that spermatogenesis (spermatogonial proliferation, the formation of spermatocytes and spermatids) occurs between 22:00 and 10:00, and spermiation (release of spermatozoa into the lobular lumen from the cysts) occurs between 14:00 and 22:00. Thus, spermatogenesis and spermiation occur on a daily basis in the male Japanese flounder. Serum T and 11-KT levels showed no significant fluctuation throughout the day. Serum 17α,20β-DP was maintained at a low or undetectable level throughout the experimental period, but showed a surge (110pg/m/) at 22:00. This short-lived 17α,20β-DP surge corresponded to the peak of spermiation. This study demonstrates, therefore, the existence of a diurnal periodicity in (1) spermatogenesis and spermiation, and (2) 17α,20β-DP production.
AB - Testicular activity, as represented by the amount of each type of testicular germ cell in the seminal lobules, and the serum levels of three major male teleost steroids—testosterone (T), 11-ketotestosterone (11-KT), and 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP)—were investigated during the daily spawning cycle of the male Japanese flounder Paralichthys olivaceus. B-type spermatogonia and spermatocytes increased in number from the lowest level at 22:00 (186 cells/lobule), and peaked at 10:00 (292 cells/lobule). The number of spermatozoa increased from 14:00 (370cells/lobule) and peaked at 22:00 (782 cells/lobule). In contrast, spermatid numbers decreased from 14:00 (579 cells/lobule) and showed the lowest level at 22:00 (348 cells/lobule). These results indicate that spermatogenesis (spermatogonial proliferation, the formation of spermatocytes and spermatids) occurs between 22:00 and 10:00, and spermiation (release of spermatozoa into the lobular lumen from the cysts) occurs between 14:00 and 22:00. Thus, spermatogenesis and spermiation occur on a daily basis in the male Japanese flounder. Serum T and 11-KT levels showed no significant fluctuation throughout the day. Serum 17α,20β-DP was maintained at a low or undetectable level throughout the experimental period, but showed a surge (110pg/m/) at 22:00. This short-lived 17α,20β-DP surge corresponded to the peak of spermiation. This study demonstrates, therefore, the existence of a diurnal periodicity in (1) spermatogenesis and spermiation, and (2) 17α,20β-DP production.
UR - http://www.scopus.com/inward/record.url?scp=85008006468&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85008006468&partnerID=8YFLogxK
U2 - 10.2331/fishsci.61.17
DO - 10.2331/fishsci.61.17
M3 - Article
AN - SCOPUS:85008006468
VL - 61
SP - 17
EP - 23
JO - Fisheries Science
JF - Fisheries Science
SN - 0919-9268
IS - 1
ER -