(1) Embryonic development of fertilized eggs Embryo development of A. sinensis eggs is greatly affected by temperature. From the fertilized eggs to the larvae, it takes about 150 hours at a water temperature of 29 to 31 °C. When water temperature is 25 to 27 °C, it takes 168. Hours or so.
Astragalus eggs have an egg diameter of 3.3-3.7 mm and an egg weight of about 35 mg. The yolk is even and the egg membrane is colorless and translucent. After 12 to 20 minutes after the egg is fertilized, the fertilized membrane is lifted to form a clear gap between the eggs. At this time, the egg diameter increases to 3.8-5.2 mm, and begins to flow through the protoplasm. At 40 to 60 minutes after fertilization, a distinct blastoderm was seen. From the time of egg fertilization until the early stages of the gastro-intestinal, the animal grades of the eggs all faced upwards.
Cleavage of: at temperature of about 25 deg.] C, about 120 minutes after egg fertilization eel, first division occurs. A second split occurred about 180 minutes after fertilization. The fertilized eggs were about 240 minutes apart, the third split, the fourth split about 300 minutes after fertilization, and about 32 cells of approximately equal size were formed after 360 minutes of fertilization. Arrangement, then splitting continues, after a multi-cell stage, develops to the blastocyst stage about 12 hours after fertilization.
Gastrointestinal phase: As the cleavage progresses, the animal's polar cells become smaller and smaller and the gastro-intestinal phase begins. About 18 hours after fertilization, animal pole cells were packaged and entered the early stages of the gastroenterus to form a ring-shaped bulging embryonic ring. About 21 hours after fertilization, embryo shields appeared. About half an hour after fertilization, about 1/2 of the eggs are packaged and neurocytes are formed. About 44 hours after fertilization, it developed into a period of large yolk thrombosis. About 48 hours after fertilization, enter the period of small yolk thrombosis. About 60 hours after fertilization, the embryo pores were closed.
During the neurulation period: At the same time as the package under the original intestine, the cells of the animal's pole began to involute, and about 21 hours after the fertilization, the embryo shield formed and was continuously thickened to form the original neural pole. After that, with the lower bowel of the original intestine, the nerve plate continued to develop and elongate, and about 65 hours after fertilization, a nerve groove was formed when the tail bud began to grow.
Organogenesis: about 60 hours after fertilization. A thin, straight tubular heart forms and begins to bounce slowly, about 45 times per minute, with no red blood cells in the blood. Since then, the two ends of the heart have been gradually enlarged, and the heart and ears have been divided into the ventricles, and bending has occurred. About 90 hours after fertilization, formed "S" shape of the heart, heart rate 90 times per minute, blood, red blood cells and red. The embryo pores are closed and the tail buds begin to grow. About 77 hours after fertilization, the tail end bends forward. About 95 hours after fertilization, the tail extends backwards and stretches continuously. About 65 hours after fertilization, the head of the neuroblast enlarges and a rhombic ventricle is formed. About 85 hours after fertilization, the optic vesicles appeared on both sides of the ventricle, and crystals formed about 100 hours after fertilization. About 69 hours after fertilization, pectoral fins form and continue to flap around 90 times per minute. About 94 hours after fertilization, the fins formed on the back and tail of the embryo. When the yolk sac disappeared, the pectoral fins and fins disappeared.
At a water temperature of 21 °C, larvae broke out 327 hours (288 to 366 hours) after fertilization. At this length is generally 12 to 20 mm, just release relatively large yolk sac larvae, approximately 3 mm diameter. The larvae can only lie sideways on the bottom or do struggling.
(2) Development of larvae The larvae still live on the yolk sac after hatching. The yolk sac completely disappeared when the total length was about 28 mm and the length of the jaw was 1.2 mm. The fins on the pectoral fin, back, and tail also disappeared. The pigment cells covered the head, making the fish dark brown and the larvae could be in the water. Swim quickly and start feeding on small zooplankton and silkworms.
Astragalus eggs have an egg diameter of 3.3-3.7 mm and an egg weight of about 35 mg. The yolk is even and the egg membrane is colorless and translucent. After 12 to 20 minutes after the egg is fertilized, the fertilized membrane is lifted to form a clear gap between the eggs. At this time, the egg diameter increases to 3.8-5.2 mm, and begins to flow through the protoplasm. At 40 to 60 minutes after fertilization, a distinct blastoderm was seen. From the time of egg fertilization until the early stages of the gastro-intestinal, the animal grades of the eggs all faced upwards.
Cleavage of: at temperature of about 25 deg.] C, about 120 minutes after egg fertilization eel, first division occurs. A second split occurred about 180 minutes after fertilization. The fertilized eggs were about 240 minutes apart, the third split, the fourth split about 300 minutes after fertilization, and about 32 cells of approximately equal size were formed after 360 minutes of fertilization. Arrangement, then splitting continues, after a multi-cell stage, develops to the blastocyst stage about 12 hours after fertilization.
Gastrointestinal phase: As the cleavage progresses, the animal's polar cells become smaller and smaller and the gastro-intestinal phase begins. About 18 hours after fertilization, animal pole cells were packaged and entered the early stages of the gastroenterus to form a ring-shaped bulging embryonic ring. About 21 hours after fertilization, embryo shields appeared. About half an hour after fertilization, about 1/2 of the eggs are packaged and neurocytes are formed. About 44 hours after fertilization, it developed into a period of large yolk thrombosis. About 48 hours after fertilization, enter the period of small yolk thrombosis. About 60 hours after fertilization, the embryo pores were closed.
During the neurulation period: At the same time as the package under the original intestine, the cells of the animal's pole began to involute, and about 21 hours after the fertilization, the embryo shield formed and was continuously thickened to form the original neural pole. After that, with the lower bowel of the original intestine, the nerve plate continued to develop and elongate, and about 65 hours after fertilization, a nerve groove was formed when the tail bud began to grow.
Organogenesis: about 60 hours after fertilization. A thin, straight tubular heart forms and begins to bounce slowly, about 45 times per minute, with no red blood cells in the blood. Since then, the two ends of the heart have been gradually enlarged, and the heart and ears have been divided into the ventricles, and bending has occurred. About 90 hours after fertilization, formed "S" shape of the heart, heart rate 90 times per minute, blood, red blood cells and red. The embryo pores are closed and the tail buds begin to grow. About 77 hours after fertilization, the tail end bends forward. About 95 hours after fertilization, the tail extends backwards and stretches continuously. About 65 hours after fertilization, the head of the neuroblast enlarges and a rhombic ventricle is formed. About 85 hours after fertilization, the optic vesicles appeared on both sides of the ventricle, and crystals formed about 100 hours after fertilization. About 69 hours after fertilization, pectoral fins form and continue to flap around 90 times per minute. About 94 hours after fertilization, the fins formed on the back and tail of the embryo. When the yolk sac disappeared, the pectoral fins and fins disappeared.
At a water temperature of 21 °C, larvae broke out 327 hours (288 to 366 hours) after fertilization. At this length is generally 12 to 20 mm, just release relatively large yolk sac larvae, approximately 3 mm diameter. The larvae can only lie sideways on the bottom or do struggling.
(2) Development of larvae The larvae still live on the yolk sac after hatching. The yolk sac completely disappeared when the total length was about 28 mm and the length of the jaw was 1.2 mm. The fins on the pectoral fin, back, and tail also disappeared. The pigment cells covered the head, making the fish dark brown and the larvae could be in the water. Swim quickly and start feeding on small zooplankton and silkworms.
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