Int. J. Morphol., 22(2):113-118, 2004.

THE CONTRIBUTION OF THE AORTIC BRANCHES IN THE VASCULARIZATION OF CERVICAL REGIONS, DURING THE DEVELOPMENT OF THE NINE BANDED ARMADILLO (Dasypus Novemcinctus, L. 1758)

CONTRIBUCIÓN DE LAS RAMAS AÓRTICAS EN LA VASCULARIZACIÓN DE LAS REGIONES CERVICALES, DURANTE EL DESARROLLO DEL TATU GALLINA (Dasypus Novemcinctus, L. 1758).

Raquel Fantin Domeniconi; Mara Alice Fernandes de Abreu; Edson José Benetti & Jacqueline da Silva Villaça

Laboratory of Anatomy of Biological Sciences Department, Faculty of Sciences of Bauru, UNESP, São Paulo, Brazil.
Project financed by FAPESP, Proc. 99/01199-6.

Correspondence to:

SUMMARY:The work describes the origin, branching and distribution of aortic branches, during the development of the armadillo, experimental model in the study of human leprosy. Using contrast injection, the branches of the subclavial, common carotid and omocervical aa. were identified as to its cooperation in irrigation of the ventral, lateral, dorsal, costal cervicals regions, encephalic and the thyroid gland.

KEY WORDS: 1. Armadillo; 2. Irrigation; 3. Cervical regions; 4. Anatomy; 5. Development.

RESUMEN: El trabajo describe el origen, ramificación y distribución de las ramas aórticas, durante el desarrollo del tatu gallina, modelo experimental en el estudio de la hanseniasis humana. Aplicando inyección de contraste, se identificaron las ramas de las aa. subclavia, carótida común y omocervical, y su contribución en la irrigación de las regiones cervicales ventral, lateral, dorsal, encefálica y de la glándula tiroide.

PALABRAS CLAVE: 1. Tatu gallina; 2. Irrigación; 3. Región cervical; 4. Anatomía; 5. Desarrollo.

INTRODUCTION

There is in the specialized literature, lack of works related to the anatomy of the armadillo (Dasypus novemcinctus). That animal is from Edentata super-order, Dasypodidae family and Dasypus gender (Caparo, 1979). Native from Mexico and found in the southeast of the USA and in South America (Talmage & Buchanan, 1954), it belongs to this gender, the Dasypus novemcinctus, being the most numerous of the twenty species already described.

This study becomes interesting, for the fact that this animal is used as an experimental model in human leprosy research, which point that the originator bacillus is genetically identical to the human Mycobacterium leprae (Opromolla et al., 1980; Folse & Smith, 1983; Meier et al., 1983). The armadillos contain adaptive and primitive characteristics in both anatomical and physiological aspects (Galíndez et al., 2000).

It is described by Gilbert (1995), a convergence of blood, a "rede mirabile", constituted by a group of veins and arteries through where the blood flows from the body to the limbs. In this situation, when the hot blood passes through the arteries, it is cooled by the cold blood of the veins.

The study of cervical region irrigation in the armadillo makes suitable the description of the symptoms regarding the pathologies that affect the distal regions of the limbs, especially the ones caused by the Mycobacterium leprae, being pointed as a requirement to the development of the brain, toraxic and costal vascularization concept (Catala et al., 1995) and to the adjustment to surgical procedures (Sun et al., 1999). This work aims to offer morphologic bases for the knowledge of the origin, branching and distribution of the emerging aa. from the aortic arch, during the phases of development (newborn, young and adult), describing patterns of distribution of aortic branches and cooperating with the researches related to human leprosy and to compared anatomy.

MATERIAL AND METHOD

Fifteen (15) animals were collected (newborn=NB, young=Y and adult=A), identified as to sex and age, injected in the arterial system with latex Neoprene 650® (Du Pont do Brasil S.A.) and to proceed, fastened in formol solution at 10%. After dissection under magnifying glass Ramsor (2x) and stereoscopic microscope, ZEISS-Citoval 2 (10, 16 and 20x), the samples were identified and described regarding the origin, branching and the distribution pattern of the cervical aortic branches. The obtained data were schematized, documented with photos and analyzed, in relation to the responsibility of carotid, subclavian and omocervical branches in the irrigation of the different cervical regions (ventral, lateral and dorsal), encephalic and thyroid gland. The nomenclature used in this study was according to the pattern established by Schaller (1999) (International Committee of Veterinary Gross Anatomical Nomenclature).

RESULTS

The arteries that irrigate the cervical region and part of the thoracic, in the armadillo, show unpublished pattern in the described compared anatomy. From the aortic arch two (2) brachycephalic trunk emerge, left and right, the right with larger longitude in relation to the left, due to its itinerary on the trachea before bifurcating. From these trunk the common carotid and subclavian aa. are originated, emerging from the omocervical a. which cooperates with the blood afflux of the cervical regions (Fig. 1).

The comparative analysis of origin, branching and distribution of the common carotids, subclavial and omocervical aa., allowed the description of the irrigation pattern of the cervical regions, along the development, considering the right (R) and left (L) antimeres (Figs. 1 and 2).

- The right and left ventral cervical regions are mainly vascularized, by the common carotids aa. at young age (L=100%; R=60%) and adult (L and R=40%). It was also observed in relation to the young's right antimere, the cooperation of the omocervical a. (40%) in the vascularization of this region, which is of about 20%, when in the left antimere of young animals and adults. It can be verified that the thyroid gland in the newborn and its cranial pole, in young and adult animals are exclusively irrigated by common carotids aa. branches (100%). The caudal pole presents varied and inconstant vascularization; in the left antimere of young armadillos, the vascularization occurs in 60% as from the anastomosis aortocarotid and in 20% in adult, it may still occur in 20% of young animals through the subclavian a. branches.

- The irrigation of the dorsal cervical region has as main responsible omocervical a. in both antimeres (NB=20%; Y and A=100%), except on the right side of the newborn. In the young's left antimere, this same region receives branches from common carotid a. (80%), which significantly contribute to its blood supply, while in the right antimere of that age group and also, on both adults' sides, this artery is only a collaborator (20%). The vascularization of dorsal regions of the neck still receives auxiliary branches originated from the subclavian a., in percentage of growing occurrence (L of 20% for 40% and R of 20% for 60%) in newborn and adult armadillos, while in the young, such aid is limited to the right side (40%).

- The irrigation of the lateral cervical region of the neck is carried out exclusively by branches, originated from the omocervicals aa., on both sides and in all the studied age groups (100%).

- The encephalic and costal regions are preferably vascularized by branches proceeding from subclavial a., in all cases, and in the left antimere of the newborn occurs the cooperation of the axillar a. in 20% of its supply. The subclavian a. collaborates directly, also with the costal region, in the left antímero (NB=80%; A=60%) and in the right (NB and Y=60%; A=80%). However, the left costal region of the young animal is exclusively supplied by branches direct from the omocervical a. (80%).

DISCUSSION

The distribution of the carotid and subclavian branches starting from two brachycephalic trunk, one right and another applied to the left side, shown in the three studied ages, has an odd disposition if compared to the ones described for the domestic animals (Schwarze & Schroder, 1970; Anderson & Anderson, 1986; Albuquerque et al., 1987), of laboratory (Cooper & Schiller, 1975; Hebel & Stromberg, 1976; Bugge, 1992) and wild (Souza et al., 1982; Miglino et al., 1983; Carvalhal et al., 1988; Matos & Abreu Rays (1992); Carvalho et al., 1993; Souza et al., 1996).

The cranial thyroid a. was found in the armadillo, emerging from the common carotid a., at young and adult age, similarly to the one described for the horse (Schwarze & Schroder), ruminants (Oliveira et al., 1974), dog (Booth (Booth & Goshal, 1977) and cat (Orsi et al., 1977), seeing that in the man (Di Dio, 1998) and in the rabbit (Yamasaki, 1996) prevails as branch of the external carotida.

As well as observed in the armadillo, the specialized literature describes the caudal thyroid a. emerging in a varied way (of the subclavial, rising cervical, common carotid, cranial thyroid aa. and brachycephalic trunk), many times inconstant and even absent as in goats (Schwarze & Schroder, 1970). In the newborn armadillos the totality of the gland is irrigated by only branches of the common carotid a., constituting unpublished discovery before the consulted literature.

The common carotid a. shown in the young and adult as great responsible for the vascularization of the ventral cervical region in the armadillo was also reported in the literature, for the horse (Schwarze & Schroder, 1970).

The referring discoveries to vertebral a., arising from the subclavial a. in the armadillo, find support in the literature in relation to man (Jacob et al., 1990, Spence, 1991), dog (Miller, 1964; Schwarze & Schroder, 1970), horse (Schwarze & Schroder, 1970), to guinea pig (Cooper & Schiller, 1975) and to mouse (Hebel & Stromberg, 1976). These same authors also describe, the vertebral aa. emerging from the cranial cervical a. in mice and from the costocervical trunk in ruminants pigs. Still in relation to vertebral a., Schwarze & Schroder reveal its occurrence, starting from the vertebrocervical trunk in pigs and, directly, from the brachycephalic trunk in horses.

As in the armadillo, the already mentioned authors describe respectively, for the man, dog, horse, ruminant, guinea pig and mouse, a costocervical trunk originating from the subclavian a. This artery, called dorsal costocervical trunk in the armadillo, is destined to the irrigation of the dorsal region of the neck, in the right antimere of the young animal and in the left of the adult. Still in adults armadillos, a distribution of branches of the costocervical laterodorsal trunk was observed for the respective lateral and dorsal cervical regions, on the right side. The thyrocervical trunk can also cooperate with the irrigation of the cervical region, occurrence observed in armadillo as well as in man (Jacob et al.; Spence, 1991). In pig (Schwarze & Schroder), this region receives vascularization starting from the cervical branches, originated from the vertebrocervical trunk. Another artery, the vertebrocostal trunk can be identified in the armadillo, emerging from the subclavian a. in all the studied ages.

In the newborn armadillos, the vascularization of the cervical region shows predominance in the distribution of costals branches in the left antimere and vertebrals in the right one, which appear more frequently with their development. In relation to subclavian a. were observed as predominant branches, the costal and vertebrocostal aa. in the left antimere, while in the right the larger occurrence happens through vertebral and costal branches; the dorsal branches are present in small proportion, on both sides.

In the left antimere, the behavior of the costal a., in relation to the number of branches that emerge from the omocervical a. in young armadillos, seems to reflect the probable need of a larger blood flux (which come from the subclavian a. in the other two ages) for the increased locomotion activity and the consequent need of muscular nutrition, while in the adult armadillo, the exclusiveness of emergency of the costal branches starting from the subclavian a., seems to reflect the compensation in the blood supply of the right cervical region.

The analysis of the cervical branching originated from the studied arteries shows clearly for the armadillo, the possibility of larger blood afflux, justified by the growing relation of the number of branches presented by the animals, between the growth and the youth.

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Correspondence to:

Prof. Dra. Mara Alice Fernandes de Abreu
Rua Rubens Arruda, 19-180
CEP 17016-040
Bauru - SP
BRASIL Email: mafabio@fc.unesp.br mafa.bio@uol.com.br

Received: 12-11-2003
Accepted: 22-22-2004