VASCULATURE OF TESTIS , EPIDIDYMIS AND DUCTUS DEFERENS OF RABBIT . THE ARTERIES

Rajtová V. , J . Danko: Vasculature of testis, epididymis and ductus deferens of Rabbit. The Arteries. Acta Vet. Brno 2001, 70: 3-7. The vasculature of the testis, epididymis and ductus deferens was studied in twenty adult rabbits using X-ray apparatus. For filling the roentgen-contrast and also colour-contrast mass we used red lead in 10 % warm gelatin. We found an irregular origin of the bilateral aa. testiculares from the aorta. The testicular artery forms, after its pars recta, the pars convoluta with 13-20 loose loops inside the entire inguinal canal. It enters the parenchyma, then encircles the testis twice under the tunica albuginea. The r. rete testis is one of the intratesticular branches, which passes through the mediastinum testis. The rr. interlobulares originate from the r. rete testis. The epididymis is supplied by rr. epididymales (cranialis, media and caudalis) and the a. epididymalis caudalis. The spermatic duct is vascularized by the a. ductus deferentis originating from the common trunk of the a. iliaca externa. The cremaster muscle supplies the branches of the a. cremasterica and r. cremastericus from the a. ductus deferentis. Several intratesticular anastomoses were found between the parenchymal part of the a. testicularis and the rr. epididymales and also the a. epididymalis caudalis. Our study complets the arterial vasculature of the testis, epididymis and ductus deferens of rabbit. Arteries, testis, epididymis, spermatic duct, rabbit Laboratory animals have been, but also will be, appropriate subjects for those experiments that cannot be carried out in vitro. Some attention has already been paid by several authors to the structure of their bodies and organ systems (McLaughlin 1972; Barone et al. 1973; Cooper and Schi l ler 1975; Hebel and Stromberg 1976; Smallwood 1992; Popesko et al. 1992) but many details have not yet been studied. The study of anatomy, including the vasculature of the testis in domestic mammals, is closely connected with their reproduction. Similarly, in laboratory animals such study is necessary for experiments which, to a greater or lesser degree, provide knowledge which could be applied not only to domestic mammals, but also to man. Examples include the study of the effect of heavy metals on the testicular parenchyma, the effect of ionizing radiation, the effect of some medicaments, disorders in the circulation of the blood, as well as various experimental surgical interventions. Among laboratory animals, perhaps the vascularization of the rat testis has been studied the most (Har r i son 1949; Har r i son and Weine r 1949; Kormano 1967; Vrzgu lová and Hajovská 1968; Hebel and Stromberg 1976; Chubb and Desjardins 1982; Melman et al. 1985). This problem has been studied, to a much lesser degree, in the mouse (Harr ison 1949; Harr ison and Weiner 1949; Froud 1959; Suzuki 1982; Chubb and Desjardins 1982), the guinea pig (Cooper and Schi l ler 1975), the golden hamster (Michel 1959) and in the rabbit (Harr ison 1949; Harr ison and Weiner 1949; Chubb and Desjardins 1982). The purpose of the present work is to study the arterial supply and its sources in the male rabbit’s genital gland, epididymis, scrotum and the ductus deferens. ACTA VET. BRNO 2001, 70: 3–7 Address for correspondence: Prof. MVDr. Viera Rajtová, DrSc. Department of Anatomy and Histology University of Veterinary Medicine Komenského 73, 041 81 Ko‰ice, Slovak Republic Phone: +421 95 633 8192 Fax: +421 95 632 3666 E-mail: rajtova@uvm.sk http://www.vfu.cz/acta-vet/actavet.htm Materials and Methods For the study, twenty healthy male rabbits weighing 2.5-3 kg from private breeders were used. The animals were euthanized by prolonged anaesthesia administered as an inhalant using either chloroform or ether. Immediately following euthanasia, the vascular network was perfused by a physiological solution with the addition of Heparin (Léãiva) at the dose of 1 ml (5000 U. I.) per 250 ml of solution, through the left cardiac ventricle. During the injection, the v. cava cranialis was opened in order to lower the pressure in the vessels to ensure a good injection. As a filling mass which gave not only roentgen-contrast but also colour-contrast, we used red lead (tri-plumbictetroxide, Pb3O4) with a 10 % solution of warm gelatin or glycerine. In the work, the latest veterinary anatomical nomenclature is used (NAV, 1994).


Materials and Methods
For the study, twenty healthy male rabbits weighing 2.5-3 kg from private breeders were used.The animals were euthanized by prolonged anaesthesia administered as an inhalant using either chloroform or ether.Immediately following euthanasia, the vascular network was perfused by a physiological solution with the addition of Heparin (Léãiva) at the dose of 1 ml (5000 U. I.) per 250 ml of solution, through the left cardiac ventricle.During the injection, the v. cava cranialis was opened in order to lower the pressure in the vessels to ensure a good injection.As a filling mass which gave not only roentgen-contrast but also colour-contrast, we used red lead (tri-plumbictetroxide, Pb 3 O 4 ) with a 10 % solution of warm gelatin or glycerine.
In the work, the latest veterinary anatomical nomenclature is used (NAV, 1994).

Results
The testis of rabbit, as with the males of other mammals, is supplied by the a. testicularis.It originates (Plate I, Fig. 1,f) from the abdominal aorta caudally to the a. renalis, ventrolaterally or ventrally.The a. testicularis dextra emerges about 1-1.5 cm, sometimes only 0.5 cm in front of the a. testicularis sinistra.The right testicular artery arises approximately at the level of the fifth lumbar vertebra, the left at the level of the cranial part of the sixth lumbar vertebra.The a. testicularis, from its origin, runs caudo-ventrally as the pars recta in the wide plica vasculosa.Within the canalis inguinalis, which is long and wide in rabbits, the pars recta changes to the pars convoluta which is formed by 13-20 loose loops (Fig 1,f).At the extremitas capitata and along the margo epididymis, it approaches the extremitas caudata, where it perforates the tunica albuginea and continues as a subcapsular artery directly or tortuously through the margo liber.At the cranial end, it returns to the epididymal margin, where it forms slightly tortuous loops.At the extremitas caudata (in some cases also at the opposite testicular end) the testicular artery divides into two branches of almost equal thickness, which bend and continue around the testis, so that at the margo liber three arteries run side by side (Plate I, Fig 2 , II, 3b).The small secondary intratesticular branches project from both marginal arteries (Plates II, III,Figs 2c,3,5b).The thicker of them, the r.rete testis enters the mediastinum testis which is shifted closely to the epididymal margin.From the r.rete testis, tiny rr.interlobulares (Plate II, Fig. 4c) originate in all directions; they run in the septula testis and reach the marginal branches and tunica albuginea.Several anastomoses are formed between the arteries of the free and epididymal margins (Fig 2c).
The epididymis is supplied by the branches of the blood vessels emanating from two sources: a) the a. testicularis or its pars convoluta, from which originates the r.epididymalis cranialis, which vascularizes the epididymal head and fat pad (Fig 3,5c).Before reaching the epididymal head the thin small branch (r.epididymalis medius), protrudes from the a. testicularis for the head and cranial part of the epididymal body (Fig 3d).The caudal part of the epididymal body and tail are supplied with the next branch of the a. testicularis -the r. epididymalis caudalis; b) the a. epididymalis caudalis, which vascularizes the caudal part of the epididymal body and tail.It originates from the initial part of the a. iliaca externa either independently or from the common trunk (Fig. 1,g) whose branches also supply the ductus deferens and m. cremaster.The a. epididymalis caudalis above the epididymal tail is divided into 2-3 delicate branches (Figs 3,f), which enter the caudal part of the epididymal body and tail, where they run almost horizontally and give rise to more secondary branches.Some of them communicate with the r.epididymalis caudalis, with the terminal part of the a. ductus deferentis as well as with the intratesticular branches.
The a. ductus deferentis is a thin blood vessel, originating from the common trunk of the a. iliaca externa (Fig. 1,i).It runs along the ductus deferens, which it supplies.In the epididymal tail, it communicates with the terminal part of a. epididymalis caudalis and the r.epididymalis caudalis.A thin branch, the r.cremastericus for the ventral part of the m.cremaster originates above the extremitas caudata from the r.ductus deferentis.
The a. cremasterica originates from the above mentioned common trunk of the a. iliaca externa (Fig. 1j).Its several rr.musculares supply the m.cremaster and 1-3 rr.adiposi vascularize the caudal fat pad.The terminal branches of a. cremasterica enter the testicular coverings.
The following intratesticular communications have been found in our study: a) in the region of the extremitas capitata: intratesticular branches of the testicular artery with branches from the r.epididymalis cranialis (Plates II, III, Figs 4, 6); b) in the region of the extremitas caudata: intratesticular branches of the testicular artery with branches from r. epididymalis caudalis and a. epididymalis caudalis (Fig. 6, rings circle the anastomoses).

Discussion
The testes of rabbits, as with other species of mammals, supply the aa.testiculares (NAV, 1994).The origin of the testicular arteries from the aorta in male laboratory rodents varies according to species.In rats, it is situated close to the aa.renales; in some individuals, it also originates from the aa.renales or even from the truncus iliacus communis (Hebel and Stromberg 1976;M elman et al. 1985).In guinea-pigs and golden hamsters (Michel 1959;Cooper and Schiller 1975) the testicular arteries arise from the aorta at the level of the aa.renales or behind them, and in mice (Froud 1959) they emerge as branches from the aa.renales (Harrison 1949;Harrison and Weiner 1949;Chubb and Desjardins 1982) have not reported the exact sites of the origin of the aa.testiculares for the rabbit (Lagomorpha).Based upon our findings, the aa.testiculares arise irregularly from the aorta as some of its last branches.The right artery originates in front of the a. mesenterica caudalis (level with the fifth lumbar vertebra), the left at the a. mesenterica caudalis or behind it (level with the sixth lumbar vertebra).Only in two cases were the testicular arteries found to originate at the same level as reported by Popesko et al. (1992).
In all mammals, the a. testicularis has an abdominal part with a direct course (pars recta), while the part passing through the inguinal canal forms loops (pars convoluta).In some laboratory rodents, e.g.mice, these loops are missing or not apparent (Harrison and Weiner 1949;Suzuki 1982).According to Michel (1959) in the gold hamster the pars convoluta is formed by four big loops during the mating period, which in the rest period (during hibernation), however, are straightened.The pars convoluta in the rabbits studied runs throughout the inguinal canal, where it forms 13-20 loops.This data corresponds to that of Chubb and Desjardins (1982).
After reaching the testis, the a. testicularis of the rabbits studied perforates the tunica albuginea only in the proximity of the extremitas caudata and enters the parenchyma after encircling the testis twice (or three times).A similar arrangement of the a. testicularis in rabbits is reported by (Harrison (1949), Harrison and Weiner (1949), while in McLaughlin's (1972) study of the rabbit's anatomy, the arrangement of the a. testicularis is not mentioned.After the division of the a. testicularis under the tunica albuginea at the level of the margo liber of the testis, three arteries run side by side.A similar observation in rabbits was also recorded by Harrison (1949).One of the branches of the marginal arteries enters the mediastinum testis as the r.rete testis.Its fine rr.interlobulares run through the interlobular spaces.Neither Harrison (1949), Harrison and Weiner (1949) nor Chubb and Desjardins (1982) have reported the intraorgan arrangement of a. testicularis in the rabbit.Harrison and Weiner (1949) considered the circular arrangement of the a. testicularis to be a part of thermoregulatory mechanism of the testis.
According to Chubb and Desjardins (1982), the epididymis of the rabbit is supplied by the r.epididymalis superior and inferior (in the sense of NAV 1994, these are known as the r.epididymalis cranialis and caudalis) as direct branches from the a. testicularis.The independent origin of the branch for the epididymal head of the rabbit from the a. testicularis has also been described by Clavert at al. (1980).The same finding have been recorded in our material.
However, based upon our study, unlike the above-mentioned authors, part of the epididymal body and tail is also supplied by the a. epididymalis caudalis, originating from the common trunk of the initial part of the a. iliaca externa.This vessel has not been reported by Chubb and Desjardins (1982) or Popesko et al. (1992).The a. ductus deferentis, supplying the deferent duct and partially the epididymal head, originates independently or from the common trunk of the initial part of the a. iliaca externa.Its origin was also reported at the same site in the rabbit by Barone et al. (1973) and Popesko et al. (1992).
The a. cremasterica, serving not only the m.cremaster and caudal fat pad, but also the testicular coverings, represents according to our findings one of the branches of the common trunk of the a. iliaca externa.There is no mention in the literature of this small vessel its origin in connection with vascularization of the rabbit (Harrison 1949;Harrison and Weiner 1949;McLaughlin 1972;Barone et al. 1973;Chubb and Desjardins 1982;Popesko et al. 1992).

Fig. 1 .
Fig. 1.Thyroid gland of a kid affected by neonatal goitre