| Abstrakt: |
Injecting estradiol-17β (1.2 μl of 1 × 10-7 M per 10 g body weight) or estrone (1.2 μl of 2 × 10-7 M) daily into the starfish Sclerasterias mollis for 16 days at early stage one of the gametogenic cycle caused an increase in the estrone and progesterone levels in the ovaries. There was a significant increase in the sizes of oocytes and protein levels in the ovaries of treated animals, but no effect on gonad index when compared with a control group. After injection higher estrone levels were found in the ovaries than in the pyloric caeca, suggesting that the ovary is the main target organ of estrogens. In the pyloric caeca of S. mollis treated with estrogen the estrone levels increased considerably. There were also differences in the progesterone level between the estradiol-17β injected, estrone injected or control groups but not in the pyloric caeca index or in protein levels. The results of the present and earlier studies on S. mollis suggest that both estrogens and progesterone form a regulatory system to control reproduction and nutrient cycles. |
