Ovarian fluid in the three‐spined stickleback Gasterosteus aculeatus: effects of egg overripening and sex steroid treatment

Abstract

The ovarian fluid properties of the three‐spined stickleback Gasterosteus aculeatus were studied in overripe and non‐overripe ovulated female sticklebacks and in females that were implanted with Silastic capsules containing testosterone (T), oestradiol (E2), 17,20β‐dihydroxypregn‐4‐en‐3‐one (17,20β‐P) or progesterone (P4) into the abdominal cavity. Overripe females had less ovarian fluid than non‐overripe females, but with higher dry mass, higher protein concentration and lower viscosity. T and 17,20β‐P increased the amount of ovarian fluid and the fluid protein concentration was increased by 17,20β‐P. 1‐D sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE) showed that ovarian fluid contains several proteins, with high individual variability but with no consistent differences between groups. Some of the ovarian fluid proteins appeared to correspond to proteins from the eggs. The results suggest that secretion of ovarian fluid may be influenced by steroid hormones and that changes in its properties are related to the overripening of ovulated eggs. In at least some respects it appears that the changes in the ovarian fluid is a result, rather than the cause of overripening.

Ovarian fluid and its impacts on spermatozoa performance in fish: A review

“…Moreover, the microvilli-covered cells of the epithelium ovarian cavity have a secretory function to buffer the in vivo environment for oocytes, especially against external constituents via the bloodstream [25]. Accumulation of the OF and its secretory processes were also shown to be modulated by sex steroids, directly and/or indirectly [22,23,26]. In both post-spawning and overripe stickleback, Gasterosteus aculeatus Lam et al [27] showed that sex steroids stimulated OF secretion from ovarian epithelium, where ovaries of progesterone (P4)-treated fish contained a considerable amount of OF in the ovarian cavity than estradiol-17β (E 2 )-treated and control fish.…”

“…In both post-spawning and overripe stickleback, Gasterosteus aculeatus Lam et al [27] showed that sex steroids stimulated OF secretion from ovarian epithelium, where ovaries of progesterone (P4)-treated fish contained a considerable amount of OF in the ovarian cavity than estradiol-17β (E 2 )-treated and control fish. Moreover, in non-overripe ovulated female sticklebacks, implants of fish with testosterone (T) and 17,20β-dihydroxypregn-4-en-3-one (17,20β-P) increased the quantity of OF secretions [26]. Sex steroid hormone concentrations in fish OF were also measured in mature females, where progesterone showed higher concentrations in OF than blood serum (~1.20 ng/mL in serum vs. ~1.40 ng/mL in OF; [28]), but in goldfish, Carassius auratus progesterone exhibited a similar concentration in both OF and serum at ovulation and the level declined during egg over-ripening [29].…”

The effects of estradiol‐17β on the sex reversal, survival, and growth of Red Shiner and its use in the development of YY individuals

“…1989; Piferrer 2001; Huang et al. 2015; Roufidou and Borg 2019). Typically, an increased GSI is only observed in estrogen‐treated males while being decreased in females (Zha et al.…”

“…The effects that E2 treatments have on ovarian development and condition vary depending on the species. Most species, including the Threespine Stickleback Gasterosteus aculeatus, Goldfish, and Common Carp, exhibit reduced ovary size and reduced GSI values when exposed to exogenous estrogen (Komen et al 1989;Piferrer 2001;Huang et al 2015;Roufidou and Borg 2019). Typically, an increased GSI is only observed in estrogen-treated males while being decreased in females (Zha et al 2007;Lei et al 2013).…”