Int. J. Morphol., 21(4):265-272, 2003.

ARRANGEMENT AND DISTRIBUTION OF THE ARTERIAL CIRCLE
IN BRAIN OF WILD BOAR (Sus Scrofa Scrofa) LINNAEUS (1758):
QUILITATIVE AND QUANTITATIVE ANALYSIS

DISPOSICIÓN Y DISTRIBUCIÓN DEL CÍRCULO ARTERIAL CEREBRAL EN JABALÍ
(Sus Scrofa Scrofa) LINNAEUS (1758): ANÁLISIS CUALLITATIVO Y CUANTITATIVO

^*a,**Câmara Filho, J. A.; ^*a,bSherer, P. O.; ^*bSherer, R. R.; ^***Meneses, C. M. C. & ^**Babinski, M. A.

---

CÂMARA FILHO, J. A.; SHERER, P. O.; SHERER, R. R.; MENESES, C. M. C. & BABINSKI, M. A. Arrangement and distribution of the arterial circle in brain of wild boar (Sus scrofa scrofa) Linnaeus (1758): Qualitative and quantitative analysis. Int. J. Morphol., 21(4):265-272, 2003.

SUMMARY: Thirteen brains of wild boar (Sus scrofa scrofa) were investigated with the purpose to discrebe the formation and the branchings of the brain arterial circle and basilar artery, from injetions of colored latex into the arteries of the base of the brain, and to establish the degree of correlativity between the rostro-caudal, latero-lateral lengths, weight, volume, carotid and basilar arteries diameter and the length of the basilar artery. To the anatomic study male and female heardswere used, from the slaughterhouse Pro Fauna licensed to abate and comercialize wild animal and under the Federal Inspection Service (SIF) control, situated in Iguape city, São Paulo. In all animal latex was injected after what the arteries of the base of the brain were dissected and observed. The obtained results indicated a domination of the internal carotid artery in the vascularization of the brain, and positive correlation between weight and volume in relation to the lenght of the brain in rostro-caudal and latero-lateral senses, in addition weight and volume have a perfect positive correlation, when one grows the other grows in the same rate.

KEY WORDS: 1. Artery; 2. Internal carotid artery; 3. Basilar artery; 4. Brain arterial circle.

---

INTRODUCTION

Morphological and quantitative data concerning exotic wild animals is still scarce and needy of information. This data will be interesting specially in species with some potential of intensive exploration as protein source or as a biological model (Swindle et al., 1988; Menezes et al., 2001), such as the Wild Boar, a mammal of the Brazilian fauna bred under IBAMA (Brazilian Institute of Environment) control.

Wild Boar is an animal belonging to the class of mammalia, order artiodactyla and suborder suiform (Nickel et al., 1979; Nowak & Paradiso, 1983). It is an ancestral of the domestic swine and both are considered of the same specie (Sus scrofa). The breeding of these two species produce fertile descendents and the domestic swine is the result of Wild Boar multiple breeding process that began in China around 4.900 bC (Nickel et al., 1979; Nogueira-Filho, 1998; Nogueira-Filho & Nogueira, 2000). Concerning these mammals, bibliography information are very few, almost generic, and rarely offers specific data, as occurs with the cerebral arterial system.

Swine encephalic structure irrigation is mainly performed by the internal carotid artery (ICA) and basilar artery (BA). ICA is a branch of the common carotid artery (CCA), originating from the bilateral carotid trunk, whose origin is the brachiocephalic trunk. The basilar artery is formed by the vertebral arteries union in the ventral face of the medullar-spinal junction (Getty,1986).

The brain itself accounts for 2% of the corporal weight, but it uses 15% of the total cardiac debit and consumes 20% of the available total amount of oxygen (Young & Young ,1998). The nervous system as a whole has been used in comparative studies of structural development, anatomical variations, and vascular arrangements, as well as surgical model (Prada & Ferreira,2002).

There are several difficulties regarding the encephalon of the vertebrates vascularization study: inadequate denomination, lack of a pattern for the anatomical position for quadrupeds, tendency to follow the human anatomical descriptions concerning the encephalon, and countless descriptions applied to the encephalic arteries.

There is a lack of studies on wild animals, mainly of the cerebral vascularization, which is the case of the Wild Boar. It is extremely important not only to describe the blood vessels supplying the encephalon of the boar, once it is a wild animal, although bred in captivity, but also for the inevitable and necessary comparison with other groups of mammals. The knowledge of the boar cerebral vascularization can serve as a substratum for a similar morphologic literature, and also for a surgical experimental model. Researches elucidating the organization of the encephalon base vessels will certainly contribute to the experimental surgeries progress, because there are several pathological processes assaulting the cerebral vessels, as embolism, aneurysms, and thromboses.

The goal of the present study is to describe the formation and the ramifications of the arterial circuit of the encephalon and of the basilar artery of the boar, and to determine the correlation degree among the rostrum-flow, latero-lateral lengths, weight, volume, caliber of the carotid and basilar arteries, and length of the basilar artery.

MATERIAL AND METHOD

Material collection: Heads of 13 male and female animals were used. Animals originate from the Pro Fauna Ltda., abattoir licensed for slaughtering and commercialization of wild animals, and under control of the Federal Inspection Service (SIF) of IBAMA (Environment Brazilian Institute), located in the city of Iguape, in the State of São Paulo (SP-Brasil). Animals were sacrificed in agreement with the abattoir's regulations, by electric shock desensitization, were bled after their bodies were hug by the pelvic appendixes. Following the heads were sectioned and the carotid arteries of both sides dissected at the level of the neck third proximal. A catheter was then introduced in the arteries and a 10 volume peroxide injection was proceeded in one of the arteries, to avoid the formation of coagula. A wash with distilled water was performed, then an injection with red pigment (plaid) latex was accomplished, until its return by the adjacent artery was obtained, after then the vessels were closed with cotton thread. Every animal had the cranium removed and the incision of the encephalon meninges was performed. After this procedure, they were immersed in a 20% formol solution for five days for fixation. After fixation the encephala were removed from the cranial box and the dissection of the branches of the intracranial internal carotids arteries, basilar, occurred, and mapping of the ramifications for the encephalon. Measures of the encephala lengths were accomplished through a pachimeter, in the rostrum-caudal course.

Morphometrical parameters: The encephalon measures in the latero-lateral course used as a parameter the more projected portion in the temporary lobes of each antimere. Each encephalon was weighed by a precision scale and the volume obtained agreed with Mandarim-de-Lacerda (1995), who mentions weight is equal to volume. Length measures of the basic artery were taken soon after the formation by the vertebral arteries until the final bifurcation in the rostral direction. Thickness of the basic arteries in three different points was also measured, because they showed different caliber in their itinerary, and caliber arithmetic average was accomplished.

A) The first measure was obtained after their union of the vertebral arteries; B) the second caudal and emission of caudal cerebellar arteries; C) the third caudal the anastomosis with the communicant caudal artery in the rostral course, and of the internal carotid artery in the immediately previous point to its ramification in communicant caudal artery and its extension to rostral.

The obtained results were analyzed, and plotted in tables. To verify the correlation degree among the lengths of the encephalon in the rostrum-caudal direction and latero-lateral, the basilar arteries lengths, weight and volume, and caliber of the intern and basilar carotid arteries, the coefficient of correlation of Pearson was calculated through statistical program, and dispersion diagrams were used in order to represent the correlation. After the correlation calculations, statistical Student " t " tests were applied to determine the significance among the correlated variables, in agreement with Mandarim-de-Lacerda and Arango (2001).

RESULTS

Internal carotid arteries (ICA). Originating from both sides of common carotid arteries, they are equal vessels that ascend to the carotid channel in the encephalon base, perforate the dura mater, arise the caudal communicant branch, continue rostrally, ventrally passing the optical tract, and driving to the medium dorsal level to the optical nerve, and caudal to the olfactory tuberculum. They issue the medium cerebral artery extending rostrally, as the rostral cerebral artery. Their caliber varies from 1,3 mm to 1,8 mm (Table II) with an average of 1,60 mm, right ICA, and 1,54 mm, left ICA (Fig. 1).

Fig. 1. Encephalon ventral face. Internal carotid artery (1), caudal communicant artery (2), rostral branch (3), medium cerebral artery (4), rostral cerebral artery (5), optical tract (6), olfactory tuberculum (7), cortical branch (*).

Medium cerebral artery (MCA). The MCA does not have a single segment, as one to three segments arise from the rostral branch of the internal carotid artery, travelling dorsolaterally , rostral to the pyriform lobe and the ventral surface of the rostral perforated substance, reaching the lateral rhinal furrow, dorso-laterally and rostral-laterally spreading in the cerebral hemispheres (Fig. 1).

Rostral cerebral artery (RCA). It is the extension of the internal carotid artery after issuing the MCA, bordering the longitudinal fissure. After its origin, it issues from one to two small branch, creating a vessel net called rostral communicant artery. Still bordering the medium fissure, it laterally issues one to four cortical branch, which extend to the lateral olfactory tract surface, spreading in this tract and in parts of the frontal lobe of the cerebral hemispheres. After the emergence of the cortical branch, caudally to the olfactory bulb, RCA issues the internal ethmoidal artery and enters in the medium fissure, joining the contra-lateral artery at a short distance to form the common artery of the callous body (Fig. 1).

Caudal communicant artery (CCA). After arising from the ICA, the CCA caudally and ventrally proceeds to the cerebral stalks, and next to the mammilar body it issues a caudal cerebral artery, which travels the lateral face of the cerebral stalk and proceeds over the ventral surface of the cerebral stalk to the medium plan, where it issues the artery of the mesencephalic roof, and keeps on to anastomose with the contra-lateral and basilar artery (Fig. 2).

Figure 2. Encephalon ventral face. Caudal communicant artery (1), caudal cerebral artery (2), mesencephalon roof artery (3), anastomosis of the caudal communicant arteries with the basilar artery (*), basilar artery (4), rostral cerebellar artery (5), medium cerebellar artery (6), caudal cerebellar artery (7), pontine branches (8). Mammilar body (9) optical chiasm (10).

Basilar artery (BA). BA is formed after the anastomosis of the vertebral arteries around the foramen magnum next to the emergence of the first pair of the spinal cervical nerve, runs by the ventral medium fissure and by the basilar furrow in the pons until the anastomosis with the caudal communicant arteries in the mesencephalon pons transition is performed. It issues several small and caudal bulb branch. Close to the trapezoidal body it issues the caudal cerebellar arteries. Continues its route and it issues about three or four pontine arteries in the pons, and in the emergence of the trigeminus nerve it issues the medium cerebellar artery. Before its anastomosis with the caudal communicant arteries, it issues 76,92% of the right rostral cerebellar arteries, 23,08% are issued in the anastomosis point with the caudal communicant artery, while the left one 69,23% are issued by the basilar. 23,07% of the anastomosis point with the caudal communicant artery, and 7,7% are caudal communicant artery branches (Fig. 2).

Encephalon arterial circuit (EAC). EAC is composed of internal carotid arteries, such as, caudal communicant, rostral branch, rostral cerebral, and rostral communicant, in the encephalon basis, delimiting important structures, such as, the hypophysis in the central portions, the optical chiasma in the rostral portion, and the mammillary body in the caudal portion of the circuit.

All analyzed encephala showed a very regular form of the arrangement of arteries which participate of the EAC formation, which is divided in two portions from the emergence of the internal carotid artery in the encephalon base, one rostral and the other caudal (Fig. 2).

Quantitative analysis. Data regarding latero-lateral (mm), rostrum-caudal (mm), weight (g), and volume (mL) measures of 13 Wild Boars encephala are shown in Table I, while data concerning the basilar, internal right and left carotid arteries caliber, as well as basilar artery length, all measures in mm, are described in Table II. After that, we established the confidence intervals for the data population average, as well as the simple linear correlation amongst variables, two by two, and the simple linear correlation coefficient of Pearson was obtained.

Table I. Data concerning the measures in the latero-lateral (mm), rostral-caudal (mm) direction, weight (g), and volume (mL) of encephalon of 13 wild boars.
 

Animal	Latero-lateral	Rostrum-caudal	Weight	Volume
01	57,3	77,8	95	95
02	61,2	82,5	110	110
03	53,4	75,4	85	85
04	57,3	78,6	97	97
05	53,5	76,6	85	85
06	54,9	79,7	103	103
07	58,9	78,4	102	102
08	55,5	79,9	101	101
09	54,3	80,7	90	90
10	58,4	79,6	105	105
11	51,5	77,4	90	90
12	54,7	77,8	93	93
13	54,4	72,4	84	84

Thus, with the Statdisk application program, developed by Triola (1999), estimates were determined for the data contained in Table I, shown on Table III, containing the average, the standard deviations, the maximum and the minimum values, as well as the confidence intervals for the population average, 95% certainty, of latero-lateral, rostrum-caudal, weight, and volume variables of the encephalon.

The same procedure was adopted to the data contained in Table II, trough the Statdisk application program, by Triola. Averages, standard deviations, minimum and maximum values, as well as confidence intervals for the population average variables were obtained, 95% certainty, concerning the caliber of the basilar artery, right and left internal carotids, and also the basilar artery length (Table IV).

Table II. Data of caliber of basilar arteries (mm), right internal carotid (mm), and left internal carotid; and length of basilar artery of the encephalon of 13 wild boars. Measurement was not possible.
 

Animal	Basilar Artery	ICA (Right)	ICA (Left)	Basilar artery Lenght
01	1,36	1,8	1,7	33,9
02	1,43	1,5	1,5	34,6
03	1,43	---	1,6	27,5
04	1,00	1,5	---	32,4
05	1,56	1,6	1,6	29,7
06	1,00	---	1,4	28,4
07	1,26	1,3	---	31,3
08	1,23	1,7	1,7	35,9
09	1,26	---	1,3	34,2
10	1,56	1,6	1,6	38,7
11	1,30	1,8	1,5	---
12	1,30	---	1,5	37,9
13	---	---	---	---

Therefore, according to Table III we can statistically state that the averages are as follows: (a) encephalon latero-lateral length of the boar population, with 95% certainty, between 54.17£ µ £ 57,41 mm; (b) encephalon rostrum-caudal length of the boar population, with 95% certainty, between 76,69 mm £ µ £ 79,75 mm; (c) encephalon weight of the boar population, with 95% certainty, between 90,30 g µ 100,48 g; and (d) volume of the boar population, with 95% certainty, between 90,30 mL £ µ £ 100,48 mL.

Table III. Averages, standard deviations, minimum and maximum values, and confidence interval for the population average, with 95% certainty, of variables concerning the encephala of 13 wild boars.
 

Variables	Mean	SD	Minim um value	Maximum value	Confidence interval
Latero-lateral (mm)	55,79	2,68	51,50	61,20	54,17 £ µ £ 57,41
Rostrun-caudal (mm)	78,22	2,53	72,40	82,50	76,69£ µ £ 79,75
Weight (g)	95,39	8,42	84,00	110,00	90,300£ µ £ 100,48
Volume (mL)	95,39	8,42	84,00	110,00	90,300£µ £ 100,48

These variables presented in Tables I and II were correlated, two by two, thus the linear correlation coefficients of Pearson were obtained, with the "Student t" test application, at a 5% probability level, to test the null hypothesis H₀: r = 0 versus the option hypothesis H₁: r = 0 (Table V).

Therefore, according to Table IV, we can statistically state that the average of the: (a) encephalon basilar artery caliber of the boar population, with 95% certainty, is between 20 mm £ µ £ 1,42 mm; (b) encephalon internal right artery caliber of the boar population, with 95% certainty, is between 1,46 mm £ µ £ 1,74 mm; (c) encephalon internal left artery caliber of the boar population, with 95% certainty, is between1,45 mm £ µ £ 1,63 mm; and (d) encephalon basilar artery length of the boar population, with 95% certainty, between 30,67 mm £ µ £ 35,61 mm.

Table IV. Averages, standard deviations, minimum and maximum values, and confidence interval for the population average, with 95% certainty, for the arteries caliber and length of the basilar artery (mm)
 

Variables	Mean	SD	Minimum Value	Maximum Value	Confidence interval
Basilar artery	1,31	0,18	1,00	1,56	1,20 £ µ £ 1,42
ICA (Right)	1,60	0,17	1,30	1,80	1,46 £ µ £ 1,74
ICA (Left)	1,54	0,13	1,30	1,70	1,45 £ µ £ 1,63
A. basilar (Lenght)	33,140	3,68	27,500	38,700	30,67 £ µ £ 35,61

Therefore, it can be observed that the weight is highly related to the latero-lateral measure, occurring the same with the volume, that is, volume is extremely related (p<0,05) to the latero-lateral measure, thus indicating that whenever the encephalon weight (or volume) increases, there is an increase in the latero-lateral direction, and vice-versa.

Table V. Linear correlation coefficient of Pearson, between variables concerning the encephalon.  Notes: ns= nor significant at a 5% probability level by the "Student" t test. Significant at a 5% probability level by the "Student" t test."
 

Variables	Rostrum	Weight	Volume	Basilar artery	ICA (Right)	ICA (Left)	Basilar artery (Lenght)
Latero-lateral	0,54 ns	0,80 *	0,80 *	0,06 ns	-0,60 ns	0,17 ns	0,38 ns
Rostrum		0,79 *	0,79 *	-0,19 ns	-0,28 ns	-0,38 ns	0,45 ns
Weight			1,00 *	-0,19 ns	-0,44 ns	0,01 ns	0,39 ns
Volume				-0,19 ns	-0,44 ns	0,01 ns	0,39 ns
Basilar artery					0,15 ns	0,12 ns	0,22 ns
ICA (Right)						0,44 ns	0,36 ns
ICA (Left)							0,22 ns

Weight and volume are also highly correlated with the rostrum-caudal direction measure (p<0,05), indicating that whenever the encephalon weight (or volume) increases, there is an increase in the rostrum-caudal direction, and vice-versa. Weight and volume present a perfect positive correlation, and weight value is the same of the volume's, modifying the units. The other variables are not related amongst them(p>0,05).

DISCUSSION

Internal and basilar carotid arteries and their anastomosis are located at the encephalon base. The arrangement formed by these anastomosis is different among the species, although there are several denominations, making the morphological studies complex.

The Veterinary Anatomical Nomina (1999) describes the swine encephalon base arteries as a circle, and calls it the brain arterial circle or Willis. De Vriese (1905) refers to the formed arrangement, when performed encephalon vascularization studies, as Willis polygon, a geometrical figure at the encephalon base. De La Torre et al. (1962) use the term Willis circle for the arterial anastomoses at the encephalon base. Alcântara & Prada (1996 a,b), use the term arterial circuit for the dog encephalon. According to observations of the present study, the encephalon base arteries do not delimitate any geometrical form corresponding to a polygon, nor to a circle. Such results confirm the findings of Alcântara & Prada (1996 a,b), who propose a revision of the Veterinary Anatomical Nomina, and state that the dog encephalon base arterial formation neither correspond to a polygon nor to a circle, but corresponds to an arterial circuit. The term circuit is defined as a line limiting any closed area and the word circle corresponds to a region forming a circumference. Once no polygon nor circle forms were observed, the present study use the term brain arterial circuit, agreeing with Alcântara & Prada (1996), who utilize this term for dogs.

De La Torre et al. (1959) describe the dog encephalon vascularization originating from the vertebral and internal carotid arteries. The internal carotid artery is divided in anterior and posterior branch, and the latter is the posterior communicant artery, showing the same caliber of the internal carotid artery. The anterior branch bifurcates into medium cerebral artery and anterior cerebral artery, which is not in agreement with Alcântara & Prada (1996a), who report that the internal carotid artery bifurcates into a rostral branch, which branches off into medium cerebral artery and rostral cerebral, and caudal branch, addressing caudally, and performing anastomosis with the basilar artery. Getty mentions that the internal carotid artery of domestic hog subdivides in branch, a rostral one, which branches off into the medium cerebral artery, and rostral cerebral artery, and a caudal branch, called caudal communicant artery, which can be divided into two portions, one proximal and another distal, named mesencephalic artery, from the caudal cerebral artery issuing. It is called communicant, as it performs the anastomosis with the basilar artery. Nevertheless, it has been observed in this study the internal carotid artery issuing two branches: the rostral, spreading out into a medium cerebral artery and rostrum cerebral, and the caudal branch, called caudal communicant artery, which will branch off during its route, where the main branch is the caudal cerebral artery. This work agrees with Alcântara & Prada (1996a) regarding the nomenclature used for the rostrally ramification of the internal carotid artery, although disagrees with them when they call the internal carotid artery caudal bifurcation a caudal branch, and agrees with De La Torre et al. (1959), who named the caudal communicant artery as the internal carotid artery caudal branch. Observations of the present study are absolutely contrary to the ones reported by Nanda (1986), who mentions that the internal carotid artery issues three branches: the caudal and rostral communicant arteries, and the medium cerebral artery.

One to three medium cerebral arteries originating from the internal carotid artery rostral branch were observed by the present study. These data are also found in Getty. According to De La Torre et al. (1959), vertebral arteries of dogs arise from the subclavian arteries, ascending in the transverse channel by transverse foramens. Vertebral arteries join and form the basilar artery. The latter has frequently a sinuous route in the ventral face of the encephalic trunk; it is divided in the highest point to form the anterior portion of the Willis circle. The basilar artery ventrally goes to the cerebral trunk sinuously, bifurcating into two communicant posterior arteries. The greatest posterior communicant arteries branches are the superior and the inferior cerebellar arteries. Getty mentions that the swine rostral cerebellar artery is the caudal communicant artery branch, and according to observations of this study regarding the boar basilar artery, we can state that the basilar artery is formed from the anastomosis of the vertebral arteries, which issues several branch, where the main ones are the medium cerebellar arteries. The right cerebellar artery is issued 76,92% , and 23,08% are issued in the anastomosis point with the caudal communicant artery, while the left one 69,23% are issued by the basilar. 23,07% of the anastomosis point with the caudal communicant artery, and 7,7% are caudal communicant artery branches, which disagrees with the above mentioned authors, when they mention the rostral cerebellar artery as the predominant branch of the caudal communicant artery.

According to Gillilan (1976), the internal carotid artery of primitive primates still is the bigger source of blood supply for the brain, but the vertebral arteries contribute for the encephalic trunk supply. The pattern of arteries supplying superior mammals encephalon is variable and complex. In the domestic hog the encephalon receives blood supply from the internal and basilar carotid arteries, with which we agree, because it has been observed by our results that both arteries contribute for the encephalon vascularization. The basilar artery is responsible for nurturing the encephalic trunk and cerebellum, and the internal carotid for supplying the brain, which make us disagree with Goss (1988), who describes that a considerable portion of the brain is irrigated by two vertebral arteries through the basilar artery. Statistical studies were accomplished according to our results, although we were not able to perform any discussion, as no morphometric data concerning the swine encephalon, nor the boar, were found.

The term brain arterial circuit is used for the internal carotid artery ramification in the encephalon. The circuit is formed by the internal carotid arteries branch, such as: caudal communicant arteries, rostral branch, rostral cerebral arteries, and rostral communicant arteries. It is included in type I.

The rostral cerebellar arteries are basilar artery branches. There is a positive correlation between weight, volume regarding the encephalon size in the rostral-caudal and latero-lateral direction. Weight and volume have a perfect positive correlation: the increase of one of them will cause the increase of the other in the same proportion.

---

CÂMARA FILHO, J. A.; SHERER, P. O.; SHERER, R. R.; MENESES, C. M. C. & BABINSKI, M. A. Disposición y distribución del círculo arterial cerebral en Javalí (Sus scrofa scrofa) Linnaeus (1758): Análisis Cualitativo y Cuantitativo. Int. J. Morphol., 21(4):265-272, 2003.

RESUMEN: Trece cerebros de jabalí (Sus scrofa scrofa) fueron estudiados con el propósito de describir la formación y las ramas del de la arteria basilar y del círculo arterial cerebral. Las arterias de la base del cerebro fueron inyectadas con látex coloreado para establecer el grado de correlación entre el peso, volumen, diámetros y longitud de las arterias carótida interna y basilar. Para el estudio anatómico fueron usadas cabezas de jabalí, provenientes del matadero Pro-Fauna, autorizados para su comercializacion y bajo el control del Servicio de la Inspección Federal (SIF), de la ciudad de Iguape, São Paulo, Brasil. El látex fue inyectado después de la disecció de las arterias. Los resultados indicaron una dominación de la arteria carótida interna en la vascularización del cerebro, existiendo correlación positiva entre el peso y el volumen con respecto al largo del cerebro y en el sentido rostro-caudal y latero-lateral. El peso y volumen presentaron correlación positiva perfecta.

PALABRAS CLAVE: 1. Arteria; 2. Arteria carótida interna; 3. Arteria basilar; 4. Círculo arterial cerebral.

---

REFERENCES

Alcântara, M. A. & Prada, I. L. S. Arteries of basis of encephalon in dog (Canis familiaris, linnaeus, 1758). I. Anatomical study od sources and behaviour. Braz. J. of Vet. Res. Anim. Sci., 33(2):67-71, 1996a.         [ Links ]

Alcântara, M. A. & Prada, I. L. S. Arteries of basis of encephalon in dog (Canis familiaris, linnaeus, 1758). II. Formation and behaviour of the encephalon arterial circuit. Braz. J. of Vet. Res. Anim. Sci., 33(2):72-6, 1996b.         [ Links ]

Arango, H. G. Bioestatística teórica e computacional. Guanabara Koogan, Rio de Janeiro, 2001. 235p.         [ Links ]

De La Torre, E. M. G. Netsky & Meschan, I. Intracranial e extracranial circulation in the dog: anatomic and angiografic studies. Am. J. Anat.,105:343-81, 1959.         [ Links ]

De La Torre, E. O. C. & Netsky, M. A. Anatomic and angiographic studies of the vertebral basilar system in dog. Am. J. Anat., 110:187-98, 1962.         [ Links ]

De Vriese, B. Sur la signification morphologique des artères cerebrales. Archives de Biologie, 21:357-457, 1905.         [ Links ]

Getty, R. Anatomia dos Animais Domésticos. 5. ed. Guanabara Koogan. Rio de Janeiro, 1986. V. 2. 2000p.         [ Links ]

Gillilan, T. A. Extra and intra-cranial blood supply to brain of dog and cat. Am. J. Anat., 146:237-54, 1976.         [ Links ]

Goss, C. M. Anatomia. 29.ed. Guanabara Koogan, Rio de Janeiro, 1988. 1147p.         [ Links ]

Machado, A. B. Neuroanatomia funcional. 2. ed. Atheneu, São Paulo, 1993. 363p.         [ Links ]

Mandarim-de-Lacerda, C. A. Métodos quantitativos em morfologia. Eduerj, Rio de Janeiro, 1995. 131p.         [ Links ]

Menezes, D. A.; Carvalho, M. A. M.; Cavalcante Filho, M. F. & Souza, W. M. Configuração do sistema venoso portal na cutia (Dasyprocta aguti, rodentia). Braz. J. Vet. Res. Anim. Sci.,38(6): 2001.         [ Links ]

Nanda, B. S. Suprimento sanguíneo para o cérebro, p. 1513-1518. In: R. Getty, S. Sisson & J. D. Grossman (eds.), Anatomia dos Animais Doméstico, 6 ed. Guanabara Koogan, Rio de Janeiro, 1986. 1788p.         [ Links ]

Nickel. R.; Schummer, A. & Seiferle, E. The Viscera of Domestic Mammals. 2nd ed. Berlin, Verlag Paul Parey, 330 -32, 1979.         [ Links ]

Nogueira-Filho, S. L. G: Manual de criação de javali. Viçosa - mg: centro de produções técnicas, 1998. 50p.         [ Links ]

Nogueira-Filho, S. L. G.; Nogueira, S. S. C. Criação comercial de animais silvestres: produção e comercialização da carne e subprodutos na região sudeste do Brasil. Rev. econ. nordeste (Fortaleza-Brasil), 1(2), 2000.         [ Links ]

Nowak, D. M. & Paradiso, J. L. Walker's mammals of the world. 2. ed. The John Hopkins Univerity Press, 1983. pp 1184-1185.         [ Links ]

Nomenclatura Anatômica Veterinária. Editada por Oskar Schaller 1 ed. Manole, São Paulo, 1999. 614p.         [ Links ]

Prada, I. L. S. & Ferreira, C. G. Estudo anatômico das artérias da base do encéfalo de suínos (Sus scrofa domesticus, Linnaeus - 1758). Braz. J. Morph. Sci., 17: 239-40, 2000.         [ Links ]

Swindle, M. M.; Smith, A. C. & Hepburn, B. J. S. Swine as models in experimental surgery. J. Invest. Surg., 1(1):65-79, 1988.         [ Links ]

Triola, M. F. Introdução à estatística. 7. ed. LTC- Livros Técnicos e Científicos, Rio de Janeiro, 1999. 410p.         [ Links ]

Young, P. A. & Young, P. H. Bases da neuroanatomia clínica. Editora Guanabara Koogan, Rio de Janeiro, 1998. 285p.         [ Links ]

Correspondence to:
Prof. Dr. Jurandyr de Abreu Câmara Filho
Rua Joaquim Távora 223 apto 1001,
Icaraí, CEP 24230-541
Niterói, RJ
BRASIL

Email: jurabreu@vm.uff.br

Received: 18-07-2003
Accepted: 26-08-2003
 

---

^*a Post-graduation Program in Animal Biology, ^*bDepartment of Animal Biology, Federal Rural of Rio de Janeiro, UFRRJ, RJ, Brasil.

^** Department of Morphology, Federal Fluminense University, UFF, RJ, Brasil.

^*** Department of Anatomy, Estácio de Sá University, UNESA, RJ, Brasil.