The morphology of circulus arteriosus cerebri in rats

Abstract

Little has been reported concerning circulus arteriosus cerebri in adult rats. A study of rats' brains perfused with latex and fixed in formalin revealed the general configuration of a circular type pattern of the major ccrebral arteries in which all vessels were patent. N o major vessel was "string-like" and no circles were incomplete. Certain morphological features not described previously were observed. Included among the more significant of these were: (1) the asymmetrical origin of the posterior cerebral artery Pound to occur in more than half of the animals; ( 2 ) the presence of cleft-like buttonhole formations along the anterior cerebral artery o f one or both sides, a feature that was practically species characteristic; ( 3 ) the occasional presence of an anterior communicating artery supplemental to the commonly occurring side to side fusion of the two anterior cerebral arteries. Two animals, possessing two anterior communicating arteries connecting otherwise unfused anterior cerebral arteries, were exceptional; ( 4 ) an olfactory artery to the nasal cavity branched prominently from the anterior cerebral artery in all animals.Before exiting from the cranial cavity through the dorsomedial cribriforrn foramen, the olfactory artery gave origin to a laterally dirccted ramus, the central cribriform artery, that passed through the central cribriform foramen into the nasal cavity.The usefulness served by rats for investigational purposes can not be overstated; yet significant gaps exist in the descriptive anatomy of this animal.The monograph by Howell ('26), the ambitious work of Greene ( ' 3 5 ) and the impressive assemblage of anatomical essays by Farris and Griffith ('49) have collated collectively a tremendous amount of information on the rat. Yet, none of these gives more than meager information at best relative to the major encephalic vessels of the rat. Both Greene ('35) and Farris and Griffith ('49) were satisfied in accepting as identical with the rat and i n substituting for it, Adachi's ('28) description of the circle of Willis of humans, a somewhat unsatisfactory procedure for the presentation of rat morphology. Howell ('26) ignored completely any reference to the circle of Willis.Moffat's ('62) meticulous study clarified much concerning the early embryology of the arteries of the brain of the rat, and this author contributed greatly towards a fundamental understanding of basic concepts relative to the development of specific encephalic vessels (Moffat, '57, '61, 'Bla).

A New Model of Transient Cerebral Ischemia in Neonatal Rats

“…In our model, blood flow via the left vertebral artery was com pletely preserved, so the reason why there were cases that exhibited dyspnea is unclear. Since there are many variations in the circle of Willis in the rat (Brown, 1966), the ischemia may have been too se vere for these animals and, therefore, may have caused a dysfunction of the respiratory center in the brain stem. The lack of significant increase in the serum glucose concentration during ischemia indi cates the absence of epinephrine release from the adrenal glands.…”

“…The right common carotid and right sub clavian arteries (the latter supplying the right vertebral artery) both arise from the innominate artery. The circle of Willis is well developed in rats, i.e., both the anterior and posterior communicating arteries are fairly large (Brown, 1966).…”

Effect of carotid artery ligation on regional cerebral blood flow in normotensive and spontaneously hypertensive rats.

“…In addition, cerebral blood flow of normal brain remains relatively constant despite acute rises of systemic blood pressure, except at abnormally high pressures. 16 Although it has been reported that the reactivity of the cortical vasculature to vasodilators in SHR is not different from that of NTR, 4 the actual values of cerebral blood flow in SHR have not been reported in the literature. In this study, it was found that rCBF and its distribution in SHR was almost identical with that of NTR, despite significantly increased levels of MABP.…”

The morphology of circulus arteriosus cerebri in the red squirrel (Sciurus vulgaris)

“…Studies have been carried out in rats (Brown, 1966;Green, 1968), rats and mice (Firbas et al, 1973), mouse (Cook, 1965;Wiland, 1974;Szczurkowski et al, 2007), Guinea pigs (Ocal and Ozer, 1992), Guinea pigs and rabbits (Popesko et al, 1990), rabbits (Brehmer and Beleites, 1988), dogs (Miller et al, 1964), cats (McClure et al, 1973), porcupine (Aydin et al, 2005), Red squirrels (Aydin, 2008), Mongolian gerbils (Klachinka et al, 2008) and mole-rats . According to our knowledge there are no investigations on the circulus arteriosus cerebri of the ground squirrel (Spermophilus citellus) and this is the first study on this subject in ground squirrels.…”