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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.
The gonads are arranged hanging from four radial canals so that when viewed from above, the gonads are lined perpendicularly. The manubrium , colored tan, hangs down in the middle. The bell of the jellyfish (medusae) is only 1–3 cm (0.4–1.2 in) in diameter, [ 2 ] exceptionally up to 4 cm (1.6 in), and when fully extended a tentacle can be ...
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.
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
Hagfish possess gonadotropins which secrete from pituitary glands to the gonads to stimulate development. [53] This suggests that hagfish have an early version of the hypothalamic–pituitary–gonadal axis, a system which once thought to be exclusive to the Gnathostomes. Drawing of a New Zealand hagfish
Fish embryos go through a process called mid-blastula transition which is observed around the tenth cell division in some fish species. Once zygotic gene transcription starts, slow cell division begins and cell movements are observable. [4] During this time three cell populations become distinguished. The first population is the yolk syncytial ...
It is a distinct species characterized by an elongated body, large eyes, and blackish-blue stripes, growing up to 39 cm long. Inhabiting warm, deep pelagic zones of the Atlantic, Pacific, and Indian Oceans between 200 and 1,000 meters deep, this fish lives within the tentacles of the Portuguese man o' war, feeding on its tentacles and gonads ...
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.