摘要:

An account is given of the pathology and incidence of spontaneous arterial disease occurring in a series of about 2000 vertebrates, the majority of which died in captivity from natural causes. The personal observations are integrated with a fairly detailed review of the literature.Vascular lesions have been described in fish, amphibians, reptiles, birds and mammals. Particular attention is given in this paper to the comparative pathology of degenerative arterial disease and, more especially, atherosclerosis. Minor degrees of lipid infiltration of the arterial wall are seen commonly in many avian and mammalian orders, but more advanced atheromatous plaques occur frequently only in some avian orders and man. Atheroma has been observed occasionally in sub‐human primates and ungulates.Focal degeneration and calcification of the arterial media constitute the major arterial lesion in ungulates and marsupials; parasitic arteritides are seen principally in carnivores, equines and, possibly, reptiles. Arterial thrombosis in animals is usually secondary to local physical injury or infection; occlusive atherothrombosis is extremely rare in all animals.A hypothesis is presented on the histogenesis of atherosclerosis as it occurs in animals. It is concluded that the condition is a multifactorial disease. The role of dietary and other factors which may play a part in the pathogenesis of atherosclerosis is discussed. Age is the only factor shown to be fairly directly related to atherosclerosis, but the almost complete absence of lesions in some comparatively old animals emphasizes that atheroma is not an inevitable accompaniment of senescence. The morphological pattern of arterial disease would appear to be similar in free‐living and captive animals; and though increasing age and the conditions of captivity may potentiate lesions, it would seem likely that the primary causes of arterial disease are operative in natural, quasi‐natural or captive environ

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb02105.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Some of the features of the behaviour ofSepioteuthisare described compared with that of other squids and of cuttlefish which it has come to resemble.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb02106.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The details of tooth development inHypogeophis rostratusare described and analysed by dividing the life cycle of the tooth into a number of stages. Such divisions are based on either morphological characters or the degree of change which occurs during equal fractions of the whole life cycle. On the basis of such data it is apparent that some phases of the development of the tooth take place slowly whilst others are passed through more rapidly. Such variations result in the production of a dentition in which each locus is generally occupied by a functional tooth and a replacement tooth at an earlier stage of development.The process of tooth development in general follows the pattern described inSalamandra maculosaby Kerr (1960), and the enamel which covers the major and minor cusps of the adult tooth is considered to be of ectodermal origin. A stage at which the enamel matrix occurs in an uncalcified stage has not been found inHypogeophis rostratusand it is assumed that calcification of the enamel occurs almost simultaneously with the production of its organic matrix. The crown and the pedicel of the mature tooth are connected by a ring of fibres, and it seems likely that the asymmetrical pedicel is ankylosed to the jaw bone by a thin layer of cement.The mechanism of tooth succession is investigated and it is clear that both tooth production and tooth replacement occur in a synchronous manner. The term Zahnreihen (Woerdeman, 1919, 1921, and Edmund 1960, 1962) is accepted, and used in the description of tooth succession. It is clear that tooth production and replacement occur in much the same manner as in the reptiles (and possibly in all non‐mammalian vertebrates (Edmund, 1960)) and can be explained by the fact that the Zahnreihen are on average 2·4 tooth spaces apart and that each replacement wave (which travels craniad along the jaw) usually contains about six teeth. The results obtained inH. rostratusin no way conflict with the idea that the Zahnreihen are produced by stimuli which travel caudad along the jaw and that the replacement waves may run in the reverse direction.A theoretical template based on Zahnreihen 2·4 spaces apart is constructed and shows that replacement waves contain six teeth and run craniad along the jaw. It is pointed out that the observed facts do not exactly follow the theoretical pattern in that the distance between successive Zahnreihen may vary and that replacement rows may involve more or less than six teeth. Finally it is affirmed that such deviations are to be regarded as normal variations in the process of tooth production and replacem

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb02107.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY