الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
The present experimental work was carried out in ”Texas cooperative fish & wildlife research unit” at Texas Tech University, Texas, USA, in cooperation with Physiology Dept., Faculty of Vet. Med. (Moshtohor) Benha branch of Zagazig University, Egypt, during the period from March, 1998 to Decemper,1999.
• The first experiment.
The aim of the present work was to study the effect of environmental temperature on gonadal condition and development in both male and female largemouth bass.
The study includes 2000 of largemouth bass fry 11 day-age, obtained from A.E. Woods fish Hatchery , Parks & wildlife department San Marcos, Texas. After holding the fish for 2 weeks the fish were divided into 18 ”ten gallon” aquaria-average 65-70 fish/aquarium.
The average of heat in control group was 23°C where as groups was raised gradually to reach 35.0 ±0.5°C within 3 days. Then the treatment extend to 3 weeks except in continuous heat treatment was applied for 17 weeks continuously.
Samples were taken. by getting 3 fish from each aquarium, i.e. fish/group before and after each treatment. Considering some sample are representative for more than one group in case of semilar group condition.
Sampling time were performed as follow at 6 weeks (early start of heat treatment), 9 weeks (end of early heat treatment), 20 weeks (start of
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Summary
late heat treatment), 23 weeks, 34 (11 weeks after the end of all treatment), 52 (29 weeks after the end of all treatment).
The results revealed that:
•Degeneration in germ cells, of female ovary due to the effect of early heat treatment in treated group whereas the control group didn’t.
•By the end of late treatment degeneration was found in male germ cells in testis, with the stoppage of spermatogenesis.
•In group # 5 (early & late heat treatment) degeneration in both male & female germ cells with the stoppage of spermatogenesis and oogenesis.
The groups randomly divided as follow:
•Group 1 used as control.
•Group 2 used as early heat treatment group.
•Group 3 used as late heat treatment group.
•Group 4 used as combined early & late heat treatments group.
•Group 5 used as continuous heat treatment group.
The fish were kept in the tanks for 3 weeks under constant temperature 23°C before the onset of the first heat treatment.
•In continuously heat treated group, the germ cells were badly affected with temperature, diffuse degeneration and stoppage in the spermatogenesis. Significant decrease in the testicular growth started at the week 20 (14 week after starting the heat treatment).
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Summary
Also degeneration was found in the some time. All treatments at 23 weeks age, Another two samples were taken at 34 weeks, and 52 weeks of age showed that testis was reactivated , but the size is still smaller than control testis. Ovary also, was reactivated but the developmental stages still behind that of the control ovary.
- Fibrosis and collagenization in testis and ovary were clearly detcted due to the heat treat ment
- Mortality rate was as follow: in control group was 25% , in group 2 group was 33% in group 4 group was 30% in group 5 group was 39% in group 6 group was 55%.
• The second experiment
This experiment was performed on channel catfish (lctalurus punctatus).
Aim of work was to find out the reason of degeneration to of germ cell in gonads of fish.
The experiment included 189 yearling catfish obtained from Bassinger fish farm, Oklahoma, USA.
Piolt experiment was performed to detect the optimum period and effective temperature which cause germ cell degeneration .
Then, the main experiment included 84 catfish were divided into 12 tank (20gallons) 7 fish / Tank . Then the groups were divided randomly 3 Tanks / groups as follow:-
a)group I control at 28°C.
b)group 2 treaed at 32°C.
c)group 3 treaed at 34°C.
d)group 4 treaed at 36°C.
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Samples were taken after 3 and 4 weeks from the onset of heat treatment, by getting 6 fishes in each sample (2 fish / Tank).
The results showed that:-
a)Ovary didn’t affected in concern of size nor the body size .
b)Treatments in group 3 & 4 (34°C’ 36°C) were significantly (P< 0.5) increase degeneration in ovarian germ cells .
Heat treatments had a clear fibrosis and collagenization specially in males. Moreover, both 34°C and 36°C treatments were significantly increase the incedence of apoptosis in male germ cells , especially the spermatocytes. Mortality rate at group 3 (34°C’) was 4.7% and 9.4% in group 4 (36°C) and zero % in other groups .
Finally 5 we can conclude that:
A)Heat treatment have direct lethal effect on the male and female germ cells in fish.
B)Fibrosis and collagenization in ovary & testis is a resutt of environmental heat treatment.
C)Prograrnmed cell death was the reason of germ cell degeneration in fish gonads due to heat treatments (34& 36°C).
D)No negative effect to the growth of fish continuous heat treatment.
E) We recommend application of environmental temperature instead of chemical and
hormonal manipulation of sex , to control the unwanted reproduction in fish farms.