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Fish reproductive organs include testes and ovaries.In most species, gonads are paired organs of similar size, which can be partially or totally fused. [1] There may also be a range of secondary organs that increase reproductive fitness.
They discovered that fish treated with aromatase inhibitors showed decreased gonodal weight, plasma estrogen level and spermatogonial proliferation in the testis as well as increased androgen levels. Their results suggest that estrogens are important in the regulation of spermatogenesis in this protogynous hermaphrodite.
2.1 Reproduction. 2.2 Growth and development. ... they eat a variety of crustaceans and fish, ... The gonads are located in the stomach lining, ...
The lancelet is a small, translucent, fish-like animal that is one of the closest living invertebrate relatives of the vertebrates. [ 80 ] [ 81 ] The lancelets were traditionally seen as the sister lineage to the vertebrates ; in turn, these two groups together (sometimes called Notochordata) were considered the sister group to the Tunicata ...
A gonad, sex gland, or reproductive gland [1] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [2] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells
In addition, teleost fish possess a thymus, spleen and scattered immune areas within mucosal tissues (e.g. in the skin, gills, gut and gonads). Much like the mammalian immune system, teleost erythrocytes, neutrophils and granulocytes are believed to reside in the spleen whereas lymphocytes are the major cell type found in the thymus.
While protogynous fish are found within species dominated by larger males, protandrous fish are within large female dominant species, such as the clown fish (Amphiprion). [12] [13] Within the clown fish populations, males develop bi-sexual gonads—mature testis and immature ovaries—while the dominant females only possess ovaries. In cases of ...
The gonads are four yellowish structures embedded in the surface of the epidermis beneath the radial canals. The ovaries are more granular in appearance than the testes (sexes are separate). The gametes are shed into the sea, and the zygotes develop into ciliated planular larvae which grow into minute polyps.