Gonadal development and plasma steroid levels during pubertal development in captive-reared striped bass,Morone saxatilis

Abstract

Puberty is the period during which full sexual development occurs and the capacity to reproduce is acquired. Despite its importance, our understanding of the endocrine regulation of puberty in lower vertebrates is still limited. The objective of the present study was to describe the changes in gonadal development and plasma steroid levels in a relatively late maturing species, the striped bass, during the first four years of life. In about 65% of the females, puberty was initiated during the third year. Although gonadosomatic index (GSI) and oocyte diameter increased during this year, this first cycle was characterized by a heterogeneous population of developing oocytes, a relatively low mean maximum oocyte diameter, and an absence of yolk granules in the oocytes. Plasma 17β‐estradiol (E2) levels were low in all three‐year‐old fish, suggesting that an insufficient stimulation of vitellogenin production by E2 may underlie the lack of vitellogenin incorporation into developing oocytes. All monitored parameters increased during the fourth year, but were still below the values attained by older females. In about 60% of the males, puberty was initiated during the first year and all males were mature by the third year. During the first two years, several immature males initiated spermatogenesis without reaching full maturity. In mature males, mean GSI, plasma testosterone, and 11‐ketotestosterone levels increased simultaneously, reaching higher values each subsequent year. Our results indicate that, similar to the situation in mammals, more than one reproductive cycle is required in striped bass before complete adulthood is reached. J. Exp. Zool. 286:49–63, 2000. © 2000 Wiley‐Liss, Inc.

Reproductive biology of the endangered percid <i>Zingel asper</i> in captivity: a histological description of the male reproductive cycle

“…During spermiation, the cytoplasmic extensions of Sertoli cells became increasingly attenuated and appeared to break. After spermiation, the residual spermatozoa were reabsorbed by the Sertoli cells [25,64,77,78].…”

“…Holland et al [78,86] noticed an accelerated maturity in certain breeding fish, which, unlike those living in the natural environment, are not subjected to the effects of environmental variations (photoperiod, temperature, food availability). In an aquarium, Dabrowski et al [87] frequently observed Perca flavescens one year-old mature males, a phenomenon rarer in females.…”

11-Ketotestosterone and IGF-I increase the size of previtellogenic oocytes from shortfinned eel, Anguilla australis, in vitro

“…Although not a focal point of other investigations, increased levels of androgens (generally testosterone, rather than 11-KT) during previtellogenesis have been reported in a number of fish species, such as striped bass, Morone saxatilis (Holland et al 2000) and seahorse, Hippocampus abdominalis (Poortenaar et al 2004). In females of other species, such as killifish, Fundulus grandis (Greeley et al 1988), channel catfish, Ictalurus punctatus (Kumar et al 2000) and sweep, Scorpis lineolatus (Dedual & Pankhurst 1992), elevated androgen levels during previtellogenesis were not obvious.…”

Differential and Gonad Stage-Dependent Roles of Kisspeptin1 and Kisspeptin2 in Reproduction in the Modern Teleosts, Morone Species1

“…Mature males (n ¼ 8, GSI ¼ 4.2%) and females (n ¼ 10, GSI ¼ 2%) were sampled in January of their fourth year of age at their midgonadal development stage. More detailed information about the gonadal stages and seasonality was provided previously [50].…”