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Revista chilena de anatomía

versión impresa ISSN 0716-9868

Rev. chil. anat. v.20 n.3 Temuco  2002

http://dx.doi.org/10.4067/S0716-98682002000300011 

Rev. Chil. Anat., 20(3):295-302, 2002.

 

SISTEMATIZATION OF THE CRANIAL Vena cava IN BUFFALOS
(Bubalus bubalis bubalis _ SIMPSON, 1945)
 

SISTEMATIZACIÓN DE LA VENA CAVA CRANEAL EN BÚFALOS
(Bubalus bubalis bubalis - SIMPSON, 1945)

*Adelmar Afonso de Amorim Júnior & ** Marleyne José Afonso Accioly Lins Amorim

AMORIM JÚNIOR, A. A & AMORIM, M. J. A. A. L. Sistematization of the cranial Vena cava in buffalos (Bubalus bubalis bubalis - Simpson, 1945). Rev. Chil. Anat., 20(3):295-302, 2002.

SUMMARY: The almost complete lack of knowledge of the anatomical characteristics of this race allows us, here, to study the circulatory system in relation to the veined drainage of the large systemic venous trunks _ the cava system. In the literature many reports can be found on the arterial vascular pattern in several areas of the body in domestic animals as well as in savages; conversely, there is a shortage of pertinent data on the veined vascular pattern. For the present work 25 animals were utilized with the object of dissecting and systemizing the vessels, animals were fetuses with ages of between 5 and 9 months, 15 being females and 10 males. In the cranial vena cava the following origin tributaries were observed: External right and left jugular veins and their collateral tributaries; the internal right and left jugular veins; the mediastinial and pericardial; the internal right and left thoracic; thymic; the right and left subclavian and the right and left costocervicalvertebral venous trunk, and occasionally the thoracic duct.

KEY WORDS: 1. Cranial vena cava; 2. Caudal vena cava; 3. Buffalo; 4. Anatomy. 

INTRODUCTION

The buffalo is an original species of Africa and of Asia, diffused practically in all the continents, probably for the adaptation easiness in any adapts. It is animal rustic, precocious, fertile and docile. In America the largest flock is in Brazil, constituting a population of more than two million heads, with approximate growth of 5,4% a year (Fonseca, 1987).

During the embryonic development all the vertebrates present double cranial vena cava, Walker & Liem (1996) apud O'farrel, Griffith (1996). The animals genetically possessed to have an only vein present a transversal anastomosis between the two primitive cranial cave veins. This structure disappears for the change of the sanguine flow, given the atrophy of the primitive left vena cava origin in more caudal portion to the anastomosis. Like this, the vein of the right antimer stays as to main vein of drainage denominated cranial vena cava. This fact is observed in the domestic animals.

About to the subject, we came across in the literature several behaviors regarding the veined vascular pattern, mainly in what refers to the third cranial part of the body (Cranial cava system of the vertebrates). The disposition of this system united or bilaterally, can be summarized to proceed: (O´Farrel & Griffith)- to cranial vena cava bilaterally (Amphibious, Reptiles, Birds, Rodents, Lagomorphs, Marsupial, Insectivore, Bats and Elephants) and cranial vena cava right Unilaterally (Primates, Carnivores, Ungulate (except elephants) Cobaia and Opossum).

When consulting the allusive literature to the subject we came across some works that study the veined drainage in some domestic animals (Swine, Carnivorous). Relative information to the ruminant and specifically to our research in bubalines nothing found.

Dyce et al. (1997) and Barone (1990) affirms that the cranial vena cava (Vena cavae cranialis), receives the blood originating from the head's areas, neck, thoracic members, wall of the thorax and a part of the abdomen. Numerous are the mammals that possess two cranial vena cavas, a right and a left, whose origins are to each other similar, however your tributaries present an asymmetric disposition where the right cranial vena cava has in general, a domain a little more extensive. The origin of the cranial vena cava in the ruminant, except for sometimes in the caprins , happens for the junction of the two external jugulars right and left in the medium plan, for a brief bijugular trunk that receives to it shift the two subclavian veins. In the bovine the bijugular trunk is longer than in the caprins ones (where it can lack) and the two internal jugular veins (absent in the small ruminant) frequently form a brief common trunk that continues in the angle of encounter of the two external jugular veins. The cranial vena cava has the following flowing: internal thoracic vein, costocervical vein (has as flowing in most of the species the vertebral veins, deep cervical vein, dorsal scapular vein and supreme intercostal vein) and last and fewer developed the right azygos vein.

Ghoshal et al. (1981) describe for the ruminant that the cranial vena cava (Vena cava cranialis) is one of the two larger veins of the systemic circulation. It arises in the veined breast (Sinus venarum cavarum) of the right atrium of the heart and it is destined to supply the cranial part of the body that includes the head, neck, thorax, thoracic member and part of the abdominal wall.

Of the part, Nickel (1981), Schwarze & Schröder (1972), expose that the cranial vena cava in the ruminant originates itself from the cranium-dorsal part of the veined breast of the right atrium, and that opening of the thoracic cavity creates the branches: Right azygos vein, right and left costocervical veins (vertebral veins, deep cervical vein, dorsal scapular veins), right and left internal thoracic veins, and in the entrance of the thoracic cavity in the ruminant ones, the cranial cava vena emits the right and left subclavian veins. González & González (1961); and Zimmerl et al. (1930) Favilli (1931). Montané & Bourdelle (1917) comments that in the ruminant the veins of the great circulation are the previous and subsequent cave veins. The origin of the vena cava previous are the two jugular veins and the axillary two and tends as collateral flowing the thoracic vein interns, vertebral vein, superior cervical vein, dorsal veins and the great vein azigos. With relationship to your tributaries the author describes an trunk origin represented by the two jugular veins gathered in a small trunk with the axillary vein, and your collateral ones represented by the following veins: thoracic interns, vertebral, cervical deep, costocervical and right azigo.

MATERIAL AND METHOD

The material collected for the present work, it consists of buffalos of the Murrah race, belonging to several age groups. We used 25 fetuses with ages varying between 5 and 9 months, being 16 females and 9 males, and 3 calves bubalinos with approximately 3-4 months of age, obtained in Minas Gerais (Uberlândia), São Paulo (Ilha Solteira, Araçatuba and Açaí) and Pará (Belém), Brasil.

Of all the preparations we picked relative data to the sizes and corporal proportions of the fetuses, important information in the estimate of the fetal age, with views the dissection and sistematization of the vases in study.

By a longitudinal incision in the ventrolateral cervical area, in the jugular leak, the jugular vein was exposed it expresses (vein jugularis expresses). The vase the more possible cranial was called and, soon caudal to the point of bondage, a stem was introduced for injection with flow in the sense of the heart, tends the concern of, in the fetuses, to proceed an opening in the left costal low fence formed by the 4a, 5a and 6a rib, with the purpose of lacquering the arterial vases of the base of the heart, impeding like this the completion of the arteries of the body, in the opportunity also called the femoral vases and the intra-abdominal umbilical vein. Like this, the veins were injected with latex - Neoprene 650 red-faced with coloring specific (blue coloring suvinil).

Be pointed out that the fetal ages here mentioned they were dear for the established formulas for Abdel-Raouf & El-Naggar (1970), ratified later by Souza (1993). Saint them: Y=74 + (9/2)X (for fetuses with less than 20 cm) and Y=74 + (9/4)X (for fetuses with more than 20cm), where X represents the apex-sacred length (TO-S), equivalent at the distance of the head's highest point to the base of the tail, accompanying the curvature of the body, and Y = age.

Being like this, the dear ages can be summarized in the periods bellow: Period 1 (P1) = Fetus between 61 - 90 days or between 2 - 3 months; Period 2 (P2) = Fetus between 91 _ 120 days or between 3 - 4 months; Period 3 (P3) = Fetus between 121 - 150 days or between 4 - 5 months; Period 4 (P4) = Fetus between 151 - 180 days or between 5 - 6 months; Period 5 (P1) = Fetus between 181 - 210 days or between 6 - 7 months; Period 6 (P6) = Fetus between 211 - 240 days or between 7 - 8 months; Period 7 (P7) = Fetus between 241 - 270 days or between 8 - 9 months; Period 8 (P8) = Fetus between 271 days or more or between 9 - 10 months; then the estimative of the fetus ages in months observed are represented in Table I.

Being the animal in ventral decubitus, the dissection had beginning in the mandibular area and proceeding in the direction of the flow until the pubic area. Like this, the vases of interest of this research were visualized and isolated. In the thoracic area, we removed the breastbone having the concern of preserving the internal thoracic veins and the cranial vena cava with its tributary ones. We used for the description of our results Veterinary Anatomical Nomina (1994), and of each preparation we made schematic drawings, (Figs. 3 and 4).

As the veins are convergent vases that are born of the capillaries for fine thin branchs that continue directly with these last vases that are the thin veins, in our work we will describe the itinerary of the veins in the flow of the sanguine current and not in the against-flow, as Schmaltz (1898) and him followers made.

For the measures of the distances among the outlets of the tributary ones relative to the Vena cava, we used a paquimeter, observed by the face it interns of the referred vases (tunic interns).

Table I. Buffalos fetus ages (Bubalus bubalis L. 1758) estimated by the formules of Abdel-Raouf & El-Naggar.


Observation

Comp. A-C(cm)
Value Y
Fetal age (months)
1F
78,0

249,5

8-9
2F
74,0

240,5

7-8
3M
56,0
200,0
6-7
4M
69,5
230,4
7-8
5F

69,0

229,3
7-8
6M
72,0
236,0
7-8
7F
65,0
220,3
7-8
8F
61,5
212,4
7-8
9M
63,0
215,8
7-8
10M
71,5
234,9
7-8
11F
48,5
183,1
6-7
12F
57,0
202,3
6-7
13F
59,5
207,9
6-7

14F

53,0
193,3
6-7
15F
63,0
215,8
7-8
16F
82,0
258,5
8-9
17F
65,5
221,4
7-8
18F
65,0
220,3
7-8
19M
64,5
219,1
7-8
20M
67,0
224,8
7-8
21M
57,5
203,4
6-7
22M
73,5
239,4
7-8
23F
52,5
192,1
6-7
24F
48,3
182,7
6-7
25F
37,0
157-,3
5-6

F= Female ; M= Male      

Figs. 1 and 2. 1. Internal jugular veins right and left; 2. Veins external jugular right and left; 3. Superficial cervical vein right and left; 4. Cephalic veins right and left; 5. Subclavian veins right and left; 6. Internal thoracic veins right and left; 7. Vertebral vein; 8.Costocervical veins; 7, 8. Costocervicalvertebral trunk; 9. Right azygos vein; 10.Cranial  vena cava; 12. Caudal vena cava.

Fig.3 (1F) Showin g the ventral face the cranial vena cava with its respective tributary in buffalos

Fig.4 (5F) Showing for the ventral face the cranial vena cava with its respective tributary detaching the anastomosis between the cephalic vein and juglar left

Legends of the illustrations from Figs. 3 and 4.
Related to the cranial vena cava

Cr.C.v.

Cranial vena cava

Cd.C.v.

Caudal vena cava

Tm v.

Thymic veins

R.IT.v.

Right internal thoracic vein

L.IT.v.

Left internal thoracic vein

L.EJ.v.

Left external jugular vein

L.IJ.v.

Left Internal jugular vein

L.SC.v.

Left superficial cervical vein

L.Ce.v.

Left cephalic vein

To. d.

Thoracic duct

L.S.v.

Left subclavian vein

L.Vt.v.

Left vertebral vein

L.CC.v.

Left costocervical vein

Pe. v.

Pericardial vein

H.

Heart

R.CCVt.v.     

Right costocervicalvertebral vein

R.Az.v.

Right azygos vein 

Anastomosis in the cranial cava system

An.eJ.       

Anastomosis between the external jugular veins

 An.iJ.

Anastomosis between the Internal jugular veins

An.Vt.L.CC.

Anastomosis between the vertebral and left costocervical veins

An.Ce.lJ.

Anastomosis between the cephalic and the left jugular veins

RESULTS

The cranial vena cava measuring 7,1 cm on average (the originating from blood comes back all the supradiafragmatics structures that is: head, neck, thoracic members, thoracic wall, leaves of the ventral wall of the abdomen and the most cranial portion of the lumbar area.

It is formed in the cranial border and medial face of the equal of ribs 1a, for the confluence of the veins external jugular right and left when at level of 4a or 5a rib perforates the fibrous pericardium to reach the right atrium of the heart in a denominated dilatation of veined breast of the vena cava, most of this vein is more in the cranial mediastin to the right of the medium plan, and ventro-lateral to the windpipe, while the other part (smaller) it is in the medium mediastin beside the ascending aorta and involved by the fibrous pericardium.

Tributaries: The cranial vena cava receives in its more cranial end, that is, in the entrance of the thoracic cavity (cranial opening of the thoracic cavity) as constituent veins, the two veins external jugular right and left, the way of confluence of the external jugular veins and subclavian veins, varies with the degree of cranial opening of the thorax, then in the ruminant where this opening presents a smaller relative width (except sometimes in caprins) there is not more line of the brachiocephalic trunk; in the angle of convergence of these veins it still receives in its dorsal face the internal jugular veins right and left and in the ventral face the thoracic duct, in the course of its itinerary usually receives to each side in its lateral face the two right and left subclavian veins, soon after the internal thoracic veins right and left, that enters in your ventral face, the costocervicalvertebral veins still discharges in it (deep cervical, vertebral, intercostal, supreme intercostal and scapular dorsal veins) and right azygos vein coming of the right antimer of the body (thoracic member and thoracic wall up to the 60 intercostals space), while of the left antimer we came across the vertebral vein and vein costocervical penetrating independently in its face latero-dorsal or through a small common trunk similar to the of the opposite antimer.

It's important to say, still, that if treating of young animals noticed several coming veined branches of the thymus crossing the cranial vena cava in its lateral and ventral faces; we also noticed pericardial thin branches transposing the walls of the cranial vena cava close to the entrance of the vein left costocervical and mediastinal veins in its dorsal face.

DISCUSSION

Who to decide to study the anatomy of the veined system in ruminant, being been for so much of the Handbooks of Veterinary Anatomy, there will, surely, to confront with suscints descriptions, schematic and even precarious, lacking of relative necessary indications to the group of veined vases that composes the cava system and its flowing multiples. It is well true that referred works, in its majority, follow the criterion of examining wide and in full detail, a species pattern, the equine, restricting the other ones to appendixes or isolated volumes and summarized, however insufficient, for being used in this chapter. For this reason, certainly, we were in the conditions of obtaining complementation of the morphologic and enough data of the subject in subject to insert them in the description of the morphology of the domestic ruminants. We also got the attention for the information inserted in the chapter of Material and Method correspondent to the use of three bubalines calves with approximately 3 - 4 months of age. Our concern was the one of establishing comparison of data obtained in these animals, with those found in the fetuses, checking like this a pattern, because in the adult animals, one of the systems that present a larger number of variations is the veined, especially, when in its formation phase.

As the veins are convergent that are born of the capillary ones sanguine in the flow for fine ramuscles that are continued directly with these last vases (venules), in our work we described the itinerary of the veins, taking as base the sanguine current, and not the against flux, as made by Schmaltz, Dobberstein & Koch (1958); Dobberstein & Hoffmann (1964); Ghoshal et al. and Zietzschmann et al. (1985); International Committee On Veterinary Gross Anatomical Nomenclature. International Committee on Veterinary Histological Nomenclature. International Committee on Veterinary Embryological Nomenclature and Schaller (1999).

In the buffalos, the cranial vena cava has exclusively as flowing of origin the veins external jugular right and left, that they join at level of the first pair's of ribs cranial border in the highway of the thoracic cavity, for soon after to penetrate in the referred cavity. Once constituted this vase, we surprised the internal jugular veins being flowed separately (92%), or in common log (8%), in its dorsal portion. In contrast to our results, Schwarze and Schröder, Nickel et al., and Barone (1990), they describe that the internal jugular veins, in the bovine ones (absent in the bovid ones and ovinos), they originate from the first portion of the jugular vein it expresses, in trunk or separately. In the first case the authors denominated of common jugular vein, affirming Schwarze & Shröder, that sometimes for being so calibrous consider as collateral of the jugular vein it expresses corresponding. This data resembles each other to the described by Barone, which are not totally added with those visas in our results.

As flowing collateral and lateral of the cranial vena cava, we have for the bubalines the veins right and left subclavians that, they collect, therefore, the originating from blood of the head, neck and thoracic members areas. This result also differs partially of the informed ones for Zimmerl et al.; Schaller, Nickel et al. and Ghoshal et al., which working with ruminant describes that, sometimes in the caprins ones, the cranial vena cava forks in the veins left and right brachiocephalics or creates the veins subclavian on both sides and the bijugular trunk. For Schaller, this trunk is the odd continuation of the cranial vena cava, in cranial situation to the veins right and left subclavians. Still regarding this bijugular trunk, Ghoshal et al., appears that in the small ruminant he represents the origin of the external and internal jugular veins of the corresponding antimer. For Montané & Bourdelle and Favilli, however, the previous vena cava (cranial) is formed for the common meeting in island of the jugular and axillary veins, while that for Nickel et al., the internal jugular veins in the bovine ones (absent in the caprins and ovines), they originate from the first portion of the jugular vein it expresses, in log or separately. In the first case, the authors denominate it of common jugular vein. Our results don't add to the described by these authors, because, we surprised the internal jugular veins ending in the portion more distal of the cranial vena cava.

It is worth above to point out that Anatomical Nomina makes a small observation regarding the originated veined trunk of the union of the veins external jugular nominated for the authors described, of bijugular trunk, defining it as the most cranial part of the cranial vena cava. In its thoracic course dorso-caudally, the cranial vena cava after the flowing of the right and left subclavians, receives in your latero-dorsal face on both sides of the veined costocervicovertebral trunk (to the right 100%, and to the left 96%). We came across only case where the vertebral vein opened up separately and cranially to the vein costocervical in the cranial vena cava, what thwarts the information engraved by Zimmerl et al.; Bruni & Zimmerl (1947); Schwarze &Schroder; May (1974) and Nickel et al., when they expose that the vertebral vein, cervical deep and costocervical end in the cranial vena cava. It is worth to still point out, that the term veined costocervicovertebral trunk adopted in our researches, has as auxiliary objective the understanding of the areas drained by the referred trunk because Zimmerl et al., May, Nickel et al., Ghoshal et al., Zietzschmann et al., Barone and Schaller (1999) use the same term - vein costocervical - for the meaning above, exposing although that this vein results of the union of the deep cervical veins, intercostal supreme, scapular dorsal and vertebral, in agreement with the considered species. This result resembles each other the that found in our work.

Symmetrically to the outlet of the subclavians veins in both antimers in the cranial vena cava, came across in its ventral area, with the arrival of the thoracic veins it interns right and left separately in all the preparations. It is worth to say that the confluence of the internal thoracic veins for Schwarze & Schröder and Barone, are disposed similarly in general to the arteries, increasing, still, Zimmerl et al., the possibility of these vases disccharges in the axillary vein, such possibility, not observed in our research.

RESUMEN: Existe un escaso conocimiento de las características anatómicas del sistema circulatorio del búfalo (Bubalus bubalis bubalis) con respecto al drenaje venoso de los grandes troncos venosos sistémicos, como el sistema cava. Sin embargo, pueden encontrarse en la literaratura muchos relatos del modelo vascular arterial, en varias áreas del cuerpo de animales domésticos y salvajes; pero son pocos los datos del modelo vascular venoso.

Utilizamos 25 fetos de búfalos (Bubalus bubalis bubalis) con edades entre 5 y 9 meses, 15 hembras y 10 machos, con el objetivo de sistematizar los grandes vasos venosos que conforman la vena cava craneal. En la vena cava craneal se observaron las siguientes venas tributarias: Venas yugulares externas derecha e izquierda y sus colaterales; yugulares internas derecha e izquierda; mediastínicas y pericárdicas; torácicas internas derecha e izquierda; tímica; subclavias derecha e izquierda y los troncos venosos costocervicalvertebrales derecho e izquierdo y, algunas veces, el conducto torácico.

PALABRAS CLAVE: 1. Vena cava craneal; 2. Vena cava caudal; 3. Búfalo; 4. Anatomía.

REFERENCES

Abdel-Raouf, M. & El-Nagar, M. A.  Further study of the biometry and development  of  the  Egyptian  búfalo  foetus,  U.A.R. J. Veterinary Science, 7(1):125-40, 1970.         [ Links ]

Barone, R.  Anatomie comparée des mammifères domestiques.  2. ed. Paris, Vigot,  1990. V. 5. pp. 449-663         [ Links ]

Bruni, A & Zimmerl, U. Anatomia degli animali domestici. Milano, Francesco Vallardi, 1947. V. 2.         [ Links ]

Dobberstein, J. & Hoffmann, G. Lehrbuch der Vergleichenden Anatomie der Haustiere. Leipzig, Hirzel, 1964. V.3. pp. 46-50.         [ Links ]

Dobberstein, J. & Koch, T. Lehrbuch der Vergleichenden Anatomie der Haustiere. Band III- Gefäßlehre, Nervensytem, Sinnesorgane, Haut, Leipzig,Hirzel, 1958. V. 3. pp. 65-73         [ Links ]

Dyce, K. M.; Sack, W.O & Wensing, C. J. G.  Tratado de Anatomia Veterinária. 2. ed. Rio de Janeiro, Guanabara, 1997. pp. 461-4         [ Links ]

Favilli, N. Nozioni comparate di Anatomia e Fisiologia degli animali rurali. Torino, Unione Tipográfico- Editrice Torinese, 1931. pp. 290-1         [ Links ]

Fonseca, W.  Búfalo: estudo e comportamento. São Paulo, Ícone, 1987. pp. 34-8.         [ Links ]

González-García, J. & González-Alvarez, R.  Anatomia comparada de los  animales domésticos. 7. ed. Madrid, Canales, 1961. pp. 79-108.         [ Links ]

Ghoshal, N. G.; Koch, T. & Popesko, P.  The venous drainage of the domestic animals. Philadelphia, Saunders, 1981. pp. 3-143.         [ Links ]

International Committee on Veterinary Gross Anatomical Nomenclature. Nomina anatomica veterinária. 4. ed. Zurich and Ithaca, 1994. pp. 86-105         [ Links ]

May, N. D. S.  Anatomía del ovino _ Manual de disección. Buenos Aires, Hemisferio Sur, 1974. pp. 71-153.         [ Links ]

Montané, L. & Bourdelle, E. Anatomie régionale des animaux domestiques. II Ruminants.  Paris, Baillière, 1917. pp. 316-22.         [ Links ]

Nickel, R.; Schummer, A & Seiferle, E. The anatomy of the domestic animals. Berlin,  Parey, 1981. V.3.  pp.184-239.         [ Links ]

O'Farrell  L. &  Griffith, J. W.  Comparative anatomy of the cranial vena cava in laboratory animale. Lab. Anim. Sci., 46(4):702, 1996.         [ Links ]

Schaller, O.  Nomenclatura anatômica veterinária.  São Paulo, Manole, 1999. pp. 338-78.         [ Links ]

Schmaltz, R.  Ueber die Beschreibung der Venen. Berl: Münch. Tierärztl. Wochenschr. 1:193-5, 1898.         [ Links ]

Schwarze, E. & Schröder, L. Compendio de anatomia veterinária. Zaragoza, Acribia, 1972. V. 3. pp. 89-102.         [ Links ]

Souza, H. E. M.  Idade fetal e caracteristicas biométricas e morfológicas do útero gestante de bubalinos. Rio de Janeiro, 1993. dissertação (Mestrado) _ Universidade Federal Rural do Rio de Janeiro.         [ Links ]

Walker, W. F. & Liem, K. F.  1994. apud  O'Farrell  L.&  Griffith, J. W.  1996. p. 702.         [ Links ]

Zimmerl, U.; Bruni, A C.; Caradonna, G. B. & Prezioso, L.  Trattato di anatomia veterinaria. Milano, Francesco Vallardi V. 2. pp. 170-1, 1930.         [ Links ]

Zietzschmann, O.; Ackerknecht, E. & Grau, H. Ellenberger-Baum Handbuch der vergleichenden anatomie der Haustiere. 18 aufl. Springer, Berlin, 1985. pp. 717-40.         [ Links ]

Dirección para correspondencia:
Prof. Dra.Marleyne José Afonso Accioly Lins Amorim
Rua Moisés Correa da Silva n.030 Aptº202
CEP 51160-030
Boa Viagem
Recife- PE
Brasil

Email: mjaamorim@yahoo.com.br
slothvariegatus@hotmail.com

Recibido : 15-10-2002
Aceptado: 22-11-2002


* Departamento de Anatomía del Centro de Ciencias Biológicas de la Universidad Federal de Pernambuco, Recife, Brasil.

** Departamento de Morfología y Fisiología Animal de la Universidad Federal Rural de Pernambuco, Recife, Brasil.