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The meagre Argyrosomus regius (Asso, 1801) is a marine fish species that has an increasing aquaculture production in Europe. Lowering the age at maturity of hatchery-produced juveniles would support meagre aquaculture by reducing time between generations in selective breeding programs and reducing industrial costs for broodstock maintenance. The aim of this work was to assess the effects of a treatment with recombinant follicle stimulating hormone (rFsh), produced in ovarian cells of Chinese hamsters, on male germ cell proliferation and apoptosis in sexually immature meagre. The rFsh-treated fish had higher gonadosomatic index, larger seminiferous tubules, more abundant luminal spermatozoa, a lower density of anti-PCNA positive single A spermatogonia, a higher density of anti-PCNA positive spermatocysts and a lower incidence of germ cell apoptosis than control groups. The present study demonstrated the effectiveness of the produced rFsh in stimulating testis development and spermatogenesis in pre-pubertal meagre. Moreover, the rFsh treatment proved to be highly efficient in removing the apoptotic block of spermatogenesis observed in juvenile meagre, allowing spermatogonial survival and progress towards meiosis. The administration of rFsh did not stimulate spermatogonial self-renewal, a process whose control still needs to be elucidated. [ABSTRACT FROM AUTHOR]

Simple Summary: Spermatogenesis is a complex process through which male gametes, spermatozoa, are produced starting from stem germ cells called spermatogonia. The existing information on cat spermatogenesis is limited and somewhat contradictory. In fact, although this species is considered a long-day breeder with a reproduction period starting when the day length increases and ending in late autumn, spermatogenesis and sperm production occur throughout the year. In order to assess whether cat spermatogenesis is modulated according to a season pattern, we analyzed testes taken from feral cats orchiectomized during reproductive (February–July) and non-reproductive (November and December) periods. The results of the analyses carried out in the present study showed that spermatogonial proliferation was more intense during the reproductive period and germ cell death via apoptosis (a programmed form of cell death) increased during the non-reproductive period. Our results confirm the hypothesis that cat spermatogenesis is seasonally modulated through changes of germ cell proliferation and apoptosis, according to a common paradigm of seasonally breeding species. The domestic cat (Felis catus) is a seasonal-breeding species whose reproductive period starts when the day length increases. Since the existing information on cat spermatogenesis is limited and somewhat contradictory, in the present study, germ cell proliferation and apoptosis in feral adult tomcats orchiectomized during reproductive (reproductive group, RG; February–July) and non-reproductive (non-reproductive group, NRG; November and December) seasons were compared. Cross-sections taken from the middle third of the left testis were chemically fixed and embedded in paraffin wax. Histological sections were processed for the immunohistochemical detection of proliferating germ cells (PCNA) and for the identification of apoptotic cells (TUNEL method). The percentage of PCNA-positive spermatogonia was higher in the RG than in the NRG. On the contrary, germ cell apoptosis was higher in the NRG than in the RG. Our results confirm that cat spermatogenesis is modulated on a seasonal basis and suggests that spermatogenesis control involves changes in germ cell proliferation and apoptosis according to a common paradigm of seasonally breeding species. [ABSTRACT FROM AUTHOR]

The greater amberjack Seriola dumerili is a new aquaculture fish that may display reproductive dysfunctions. During extensive follicular atresia, which is a common reproductive dysfunction in females during vitellogenesis, part of the reabsorbed yolk returns to the liver to be metabolized and recycled. Melanomacrophage centres (MMCs) are aggregates of macrophage‐like cells that play a role in the destruction, detoxification and recycling of endogenous and exogenous materials, and have been associated with systemic stress. Wild and captive‐reared greater amberjack were sampled in the Mediterranean Sea during two different phases of the reproductive cycle. The liver of reproductively dysfunctional captive‐reared females sampled during the spawning season showed a high density of both MMCs and apoptotic cells. A weak liver anti‐cytochrome P450 monooxygenase 1A immunoreactivity was observed, suggesting that the examined fish were not exposed to environmental pollutants. We propose that the observed increase in MMCs and apoptosis in captive‐reared fish was related to the hepatic overload associated to the metabolism of yolk proteins reabsorbed during extensive follicular atresia. Since follicular atresia is a frequent physiological and pathological event in teleosts, we suggest that the reproductive state should be always assessed when MMCs are used as markers of exposure to stress or pollutants. [ABSTRACT FROM AUTHOR]

The article focuses on a study of male germ cell proliferation and apoptosis of captive-reared Atlantic bluefin tuna (ABFT) thunnus thynnus during its reproductive cycle. Topics discussed include increase of germ cell apoptosis when spermatogenesis occurred from April to May, temporal overlapping between spermatogenesis in wild and captive ABFT, and gonadotropins and steroid hormones in mammals as a survival factor that prevents germ cell apoptosis.

Highlights: [•] Apoptosis and tumor necrosis factor expression determined in bluefin tuna liver. [•] High apoptosis density found in juvenile bluefin tuna from the northern Adriatic. [•] High expression of tumor necrosis factor-2 expression found in the same specimens. [•] High apoptosis and TNF2 expression possibly related to environmental pollutants. [Copyright &y& Elsevier]