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Advisor(s)
Abstract(s)
The Lusitanian toadfish has group synchronous oocytes, which grow from November until June–July when they are released
probably as a single batch. Blood plasma levels of estradiol-17b (E2) and testosterone (T) increase during vitellogenesis and drop
rapidly during final maturation and ovulation, when 17,20b, 21-trihydroxy-4-pregnen-3-one (17,20b,21-P) levels increase. The male
reproductive apparatus is composed of paired testes and multichambered accessory glands, which secrete mucosubstances and are
connected to the spermatic duct. Changes in the gonadosomatic index of males paralleled the females but started to drop slightly
earlier. The swimbladder and accessory glands also underwent important seasonal changes in weight reaching a maximum at
spawning. T, 11-ketotestosterone (11-KT) and 17,20a-dihydroxy-4-pregnen-3-one (17,20a-P) were generally low except for a sharp
peak in June. 17,20b,21-P also peaked in June and then declined slowly. 17,20b-dihydroxy-4-pregnen-3-one (17,20a-P) was undetectable
in males and females. As with other species of the family two types of males were identified: type I males with smaller testes
(ca. 7-fold) and larger accessory glands (ca. 3-fold) and swimbladders than type II. Type I males also had significantly higher (ca. 6-
fold) 11-KT levels than type II males. This suggests a role for 11-KT in the development of structures important for reproductive
behaviour.
Description
Keywords
Reproductive cycle Gametogenesis Sex steroids Lusitanian toadfish