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The males do not have to compete with other males, and female anemone fish are typically larger. When a female dies a juvenile (male) anemone fish moves in, and "the resident male then turns into a female and reproductive advantages of the large female–small male combination continue". [22] In other fishes sex changes are reversible.
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
This dual system allowed for more complex sexual dimorphisms and greater adaptability to environmental pressures, such as mate competition and reproductive success. The divergence of hormonal regulation in mammals (testosterone and estrogen dominance) and birds ( estradiol -driven mechanisms) reflects evolutionary fine-tuning built upon the ...
Fish reproductive organs include testicles and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. [ 52 ] There may also be a range of secondary organs that increase reproductive fitness .
Gonadotropins are glycoprotein hormones secreted by gonadotropic cells of the anterior pituitary of vertebrates. [1] [2] [3] This family includes the mammalian hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the placental/chorionic gonadotropins, human chorionic gonadotropin (hCG) and equine chorionic gonadotropin (eCG), [3] as well as at least two forms of fish ...
Gonadal dysgenesis is classified as any congenital developmental disorder of the reproductive system characterized by a progressive loss of primordial germ cells on the developing gonads of an embryo. [1] [2] One type of gonadal dysgenesis is the development of functionless, fibrous tissue, termed streak gonads, instead of reproductive tissue. [3]
However, the disease can also develop without the fish showing any external signs of illness, the fish maintain a normal appetite, and then they suddenly die. The disease can progress slowly throughout an infected farm and, in the worst cases, death rates may approach 100 per cent. It is also a threat to the dwindling stocks of wild salmon.
In contrast, protandrous sex change is the male to female gonadal redifferentiation, but it is also triggered by the disappearance of the conspecific dominant, in this case the female. While protogynous fish are found within species dominated by larger males, protandrous fish are within large female dominant species, such as the clown fish ...