摘要:

Light and electron microscopy revealed the presence of ‘pear‐shaped’ cells amongst the mucosal cells of the stomach, pyloric curvature, pyloric caeca and the anterior‐most region of the intestines of perch. The cells are usually located in the distal region of the mucosa and are approximately half the height of the other mucosal cells. Electron microscopy shows that the cells are composed of thick outer sheaths which are fibrillar in appearance. The cytoplasm is characterized by electron dense rods numbering from three to fifteen, which originate from the supranuclear region of the cells and converge apically. The rest of the cytoplasm is composed of Golgi apparatus, secretory vacuoles, minute mitochondria and a network of cytoplasmic strands laden with ribosomes. The organization of organelles in these cells does not resemble that of other mucosal cells of the alimentary canal. Contrary to what has been suggested previously, the ‘pear‐shaped’ cells neither resemble nor represent stages in the formation and maturation of

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03671.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Interspecies haematological differences to MS 222 and neutralized MS 222 anaesthesia were investigated inSarotherodon mossambicus, Cyprinus carpioandSalmo gairdneriacclimated under identical laboratory conditions. Anaesthesia with MS 222 resulted in a ‘chemical stress’ in all fish, as was evident from changes in the haematological profiles of the animals. Such species specific variations in the haematology persisted throughout the whole experiment protocol which employed different concentrations of the anaesthetic. The use of neutralized MS 222, whereby aquarium water quality remained unchanged, improved the haematological profile. Possible reasons for the interspecies differences observed are discus

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03672.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of different concentrations of natural MS 222 and neutralized MS 222 were studied on the haematology ofCyprinus carpio, Sarotherodon mossambicusandSalmo gairdneri. As judged from the results, MS 222, which is acidic in nature, produced haemo‐concentration effects in all species studied, being least in the trout followed by carp andSarotherodon mossambicus. These differences are ascribed to acid‐base regulatory functions and metabolic activities of the fish species investigated. The use of neutralized MS 222 improved the haematological profiles markedly and resulted in stabilization of acid‐base parameters and red blood cells sizes and numbers. Haemoconcentration effects, however, still persisted. Trout were found to be more susceptible to the stress of MS 222 anaesthesia than carp andSarotherodon mossam

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03673.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of MS 222 and neutralized MS 222 anaesthesia on haemoglobin electrophoresis, erythrocyte adenosine triphosphate (ATP) levels and corpuscular fragility curves were studied inCyprinus carpio, Sarotherodon mossambicusandSalmo gairdneri. Haemoglobin electrophoresis showed no significant intra‐species differences in the percentage composition of the various fractions for any concentration of MS 222 and neutralized MS 222 used. Significant interspecies differences were, however, still observed. ATP levels showed intra and interspecies differences ascribed to the response of the fish species to MS 222‐induced stress and not to actual changes in erythrocyte ATP concentrations. Differences were also observed in corpuscular fragility curves for all three species when using MS 222 or neutralized MS 222 compared to curves obtained without the use of the anaesthetic, but the mechanisms involved are not cl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03674.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

This paper reports the temporal pattern of hormonally induced spawning inSparus auratafemales reared in captivity. A low dose of human chorionic gonadotropin (100–400 i.u. kg−1body weight), administered to females with oocytes in the last stages of vitello genesis, induced a daily cycle of maturation, ovulation and spawning of fertilizable eggs. This cyclic pattern lasted for a period of 4–100 days. In fish injected with saline and most of the untreated fish, all vitellogenetic eggs underwent rapid at

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03675.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

One hundred and twenty hakeMerluccius gayicaught off central Chile were examined for helminth parasites. Sixty hake were kept in ice from the catch of a trawler were examined upon arrival at port, while the other 60 hake were dissected on board immediately after collection. Ninety one per cent of hake were infected with one or more species of the following helminths: trypanorhynch plerocerci ofGrillotia dollfusiCarvajal, 1971; adult worms of the genus Clestobothrium; larval nematodes of the genera Anisakis and Phocanema; 86% of the total were infected withAnisakis sp.and 42.5% withPhocanema sp.Infection with larval nematodes increased with length of the fish and there was a greater incidence of infection among the females. There was a greater frequency of occurrence of the parasites in the viscera than in the musculature.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03676.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

To test the hypothesis that white muscle fibre portions of the myotomes are used at sustainable swimming speeds, skipjack tuna,Katsuwonus pelamis, were forced to swim against various current velocities in a water tunnel while electrical activity of the red and white muscle fibres was simultaneously recorded. Eight fish were tested, five fish graded white muscle fibres into activity at swimming speeds above their minimum hydrostatic equilibrium speed, but well below the estimated maximum sustainable swimming speed of skipjack tuna. Three other fish showed white muscle fibre activity at minimum swimming speeds, a possibly abnormal condition.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03677.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Various aspects of the reproductive physiology of the female lesser spotted dogfish,Scyliorhinus caniculaL., demonstrate marked annual cycles. Pituitary ventral lobe gonadotrophin content and plasma oestradiol and testosterone levels rise through the autumn as the ovary recrudesces and the percentage of fish bearing eggs in the oviducts increases. The pituitary gonadotrophin and plasma sex steroid levels remain elevated throughout the winter but decrease during the spring, two months prior to a fall in both the gonadosomatic index (GSI) and the percentage of fish with eggs in their oviducts. The lowest gonadotrophin and sex steroid levels are found in early summer, again preceding the minimum GSI and rate of egg‐laying by two or three months. Some of these cycles are pronounced, the pituitary gonadotrophin levels varying by more than 100‐fold, and the oestradiol levels by more than 10‐fold, throughout the year. It is concluded that the female dogfish has a very extended breeding season, though the peak frequency of egg‐laying occurs in the winter and

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03678.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

In the course of cruises by FRVScotiato study the ecology of O‐group gadoids in the northern North Sea in October 1977 and November 1978, the fish fauna of the upper 1 m of the water column were sampled with an improvised gear. The most abundant species were O‐group rocklings and clupeids and three spined sticklebacks. The frequency of occurrence of the last named and their relatively high abundance (up to 99 individuals in a 30 min haul) suggests that sticklebacks are more widely distributed throughout the open North Sea than is presently supposed. Young rocklings may amount to a considerable biomass in the near‐surface w

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03679.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The survival of Atlantic salmon smolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air‐saturation value, the 24‐h LC50 of un‐ionised ammonia is 0.15 mg NH31−1in fresh water (hardness 264 mg 1−1as CaCO3) and 0.3 mg NH31−1in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1−1in fresh water and 3.1 mg 1−1in 30% sea water, the 24‐h LC50 is 0.09 mg NH31−1and 0.12 mg NH31−1respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24‐h median for un‐acclimated fish, the median is increased between 38 and 79%, dep

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03680.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY