Abstract
Apteronotus albifrons has its cloacal aperture located in the front of the body and on the back of the lower jaw. A. albifrons possess a pair of testes attached on the mesentery below its liver on the back of the abdominal cavity. In the early days of development, the testes are in translucent elongated thin strips in nude colour. As they develop, the testes will grow thicker and become white or creamy white in color. The rear end of the testes will split whereas the front end will merge to form the vas deferens which is connected to the external environment through the cloacal aperture. Testes of A. albifrons are lobular. There are six stages in its development. At 6 months of age, the testis structure shows clear medium with primary spermatocytes and abundant spermatogonia, suggesting that development is into the stageⅡ. At 8 months of age, testes in male A. albifrons are in the shape of a thin rod in white with blood vessels in presence. Germ cells consist of spermatogonia, primary spermatocytes and spermatocytes, indicating stageⅢ development. At 11 months of age, testes in male A. albifrons grow fuller and are in creamy white with apparent blood vessels present. Primary spermatocytes, secondary spermatocytes, spermatids and a small amount of sperms are president, indicating stageⅣ of development. At 15 months of age, testes in male A. albifrons swells and consist of a large amount of sperms, reaching full maturity. This is the stageⅥof development, after which is the stage featured by testes after spermiation.
Highlights
Apteronotus albifrons has its cloacal aperture located in the front of the body and on the back of the lower jaw
The rear end of the testes will split whereas the front end will merge to form the vas deferens which is connected to the external environment through the cloacal aperture
Referring to the testicular development staging methods by Yun Liu (Liu, 1933), Yaoguang Zhang (Zhang, Luo, & Zhong, 1992) and Yundong Lou (Lou, 1980) et al and combined with the morphological features of A. albifrons testes and its germ cell distribution, six stages are identified during the development course of the testes: At stageI, testes are in pairs and closely attached to the two sides of the abdominal cavity
Summary
Take 200 A. albifrons and keep in the following condition: water temperature 28±0.5°C, pH 7.5±0.5, lighting 16hr: 8hr (lighting: dark). Feed with nematode and bloodworm once daily respectively. Take 10 fish each at 4 months of age, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 months of age respectively
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