A radiological study of the central circulation in the lungfish, Protopterus aethiopicus

The dipnoan heart is only in part structurally developed to support a separated circulation in pulmonary and systemic circuits. In the present investigation biplane angiocardiography has been used to describe the extent of such a double circulation and the factors which may modify it in the African lungfish, Protopterus aethiopicus. Contrast injections in the pulmonary vein revealed a clear tendency for aerated blood returing from the lungs to be selectively dispatched to the anterior branchial arteries giving rise to the major systemic circulation. Contrast injections in the vena cava delineated the sinus venosus as a large receiving chamber for systemic venous blood. Contraction of the sinus venosus discharged blood into the right, posterior part of the partially divided atrial space. Contrast injection in the pulmonary vein showed that vessel to pass obliquely from right to left such that blood was emptied distinctly into the left side of the atrium. During contraction the atrial space tended to retain a residual volume in its anterior undivided part which minized mixing. Ventricular filling occurred through separate right and left atrio-ventricular connections. Right-left separation in most of the ventricle was maintained by the partial ventricular septum, the trabeculated, spongelike myocardium and the mode of inflow from the atria. Mixing in the anterior undivided portion of the ventricle during the ejection phase was slight due to a streamlined ejection pattern. The outflow through the bulbus cordis occurred in discrete streams which in part were structurally separated by well developed spiral folds. In the anterior bulbus segment the spiral folds are fused and make completely separate dorsal and ventral outflow tracts. The ventral bulbus channel provides blood to the three anterior branchial arteries. The second and third branchial arteries are large and represent direct shunts to the dorsal aorta. The fourth and fifth branchial arteries are gill bearing and receive blood form the dorsal bulbus channel. The most posterior epibranchial vessels give rise to the pulmonary arteries.     

Hypophyseal angioarchitecture of common tree shrew (Tupaia glis) revealed by scanning electron microscopy study of vascular corrosion casts.

The vascular corrosion cast technique in conjunction with scanning electron microscopy (SEM) was used for the study of pituitary microvascularization in the common tree shrew (Tupaia glis). The pituitary vascular casts were obtained by infusion of low viscosity methyl methacrylate plastic (Batson's no.17) mixture. It was found that the blood supplies to the pituitary complex were from branches of the circle of Willis and could be divided into two groups. The first group consisted of two to four superior hypophyseal arteries (SHAs) branching off from the internal carotid artery supplying each half of the median eminence (ME), infundibular stalk (IS), and pars distalis (PD). The SHAs supplying the ME branched into internal and external capillary plexi. The internal plexus had a larger capillary size (approximately 15 microns in diameter), was deeper in position, and had denser and more complex capillary loops than those in the external plexus. The capillaries of the external plexus were approximately 10 microns in diameter. The two plexi drained into 15-20 hypophyseal portal veins (HPVs) which were located mainly along the ventral and ventrolateral surfaces of the IS before breaking up into large capillaries (approximately 18 microns in diameter) with an anteroposterior arrangement within the PD. The second group consisted of one inferior hypophyseal artery (IHA) on each side branching off from the internal carotid artery. These arteries gave off branches to pierce the dorsolateral and ventrolateral aspects of infundibular process (IP) before branching off to form a capillary network. They also gave rise to radiating capillaries to supply the pars intermedia (PI) surrounding the cortical area of the IP. The hypophyseal cleft separating the PI from the PD was clearly seen with very few blood vessels. The capillaries in both PD and IP joined to form confluent hypophyseal veins draining the blood into the cavernous sinus.     

Vascularization of the telencephalic choroid plexus of a ganoid fish [Acipenser ruthenus (L.)

The vascularization of the telencephalic choroid plexus of the sterlet Acipenser ruthenus, a ganoid fish, was examined by vascular corrosion casting and by light and transmission electron microscopy. The arterial supply is from the dorsal mesencephalic artery via: 1) the ventral choroidal arteries (left and right); 2) the dorsal choroidal arteries (left and right); 3) the caudal choroidal arteries (left and right); 4) the ventral arteries of the dorsal sac; and, from the olfactory arteries, via 5) the rostral choroidal arteries. The venous drainage is mainly through a single main choroidal vein that can take various courses either directly to the anterior cardinal vein or via the middle cerebral vein to the anterior cardinal vein. To a lesser extent, the plexus is drained via the lateral telencephalic veins and the ventral vein of the dorsal sac to the middle cerebral vein. By angioarchitecture and form, the plexus can be subdivided into five distinct parts: the surface network, the median folds, the large lateral folds, the small lateral folds, and the area common to the bottom of the dorsal sac and the telencephalic plexus. Diameters of terminal vessels as measured from vascular corrosion casts and from paraplast, semithin, and ultrathin sections were never less than 10 micron. It is suggested that the different areas in one plexus may have different functions with respect to secretion and absorption of cerebrospinal fluid.     

Cardiovascular effects of prostaglandin F(2 alpha) and prostaglandin E(2) in Atlantic cod (Gadus morhua)

Little is known of the cardiovascular functions of prostaglandins in non-mammalian vertebrates. There are indications that prostaglandins may have a function in haemostasis by constricting blood vessels in filament arteries in the fish gill after injury. Our aim was to examine the cardiovascular effect of the prostaglandins F(2 alpha) (PGF(2 alpha)) and E(2) (PGE(2)) with emphasis on branchial circulation. Intra-arterial injections of PGF(2 alpha) (10, 40, 160, 400 nmol kg(-1)) in cod caused a dose-dependent increase in ventral aortic blood pressure, a reduction in cardiac output, and an increase in gill vascular resistance. A contraction of filament arteries was observed with in vivo microscopy only seconds after injection. PGF(2 alpha) may therefore possibly be involved in a haemostatic vasoconstriction. In contrast, the most significant effects of PGE(2) appeared to be on the heart. PGE(2) also reduced dorsal aortic blood pressure.     

The Structure of the Hypothalamohypophysial Portal Vascular System in Acipenser ruthenus L. (Chondrostei)

The vascularization of the pituitary region in Acipenser ruthenus L. (Chondrostei) is described. The adenohypophysis has no direct arterial supply but is fed exclusively by a pituitary portal system supplied through a pair of infundibular arteries. Distinct portal vessels connect the lateral part of the primary plexus of the neurohaemal area (the median eminence) with the secondary plexus of the pituitary gland. The primary plexus enters the pars distalis paramedially, apparently without the formation of distinct portal vessels. The neuro-intermediate lobe receives its blood supply exclusively from the primary plexus. The plexus intermedius gives off capillaries to the parenchyma of the intermediate lobe (an intermediate lobe sinus system). The saccus vasculosus receives (1) a “direct” supply, i.e. branches originating directly from the cerebral arteries and (2) an “indirect” supply, i.e. capillaries from the primary plexus. The pars distalis is drained into an unpaired ventral hypophysial vein, while a dorsal hypophysial vein, also unpaired, drains the plexus intermedius. These two veins join to form the unpaired hypophysial vein. The findings are discussed from comparative and functional viewpoints.     

Localization of horseradish peroxidase (HRP)-anti-HRP complexes in cryostat sections: Influence of endotoxin on trapping of immune complexes in the spleen of the rat

Substance P-like immunoreactivity (SPLI) was studied by immunocytochemistry and radioimmunoassay in the cerebral arteries, choroid plexus and dura mater of the guinea-pig, rabbit, cat and man. The highest concentrations were found in cerebral blood vessels: 6.1 +/- 2.3 pmol/g (guinea-pig), 9.0 +/- 1.1 pmol/g (rabbit), 7.1 +/- 0.4 pmol/g (cat), and 2.4 +/- 0.9 pmol/g (man). Lower levels were obtained in the choroid plexus and dura mater. The distribution of substance P (SP)-immunoreactive nerve fibres found in various regions of the guinea-pig correlated well with the amount of SPLI measured. Sympathectomy did not alter the concentration of SPLI in the dura mater or in cerebral blood vessels. Electrical field stimulation or 124 mM potassium enhanced the spontaneous efflux of SPLI by 10 and 20%, respectively, from superfused pial arteries in vitro. These data are in support of a functional role of perivascular SP within the cranial circulation.     

The vasculature of the rat penis: a scanning electron microscopic and histologic study.

As a basis for understanding the mechanism of erection in an animal model frequently used in research in reproductive biology, the angioarchitecture of the penis of the rat has been described using scanning electron microscopy. Study of the penile vasculature of the rat indicates that the corpora cavernosa penis and the corpus spongiosum are independent erectile tissues, each with its own arterial and venous vessels. The large vascular spaces and abundant smooth muscle of the penile crura are compatible with its role in regulating blood flow to more distal penile tissues. Helicine arteries of the crura, but not the parent deep penile artery or arteries elsewhere, have muscular cushions in their walls. The venous drainage of the penile crura is via subtunical veins which are thought to be compressed during erection to elevate pressure within the penis. Large, paired cavernous veins drain the shaft of the penis. A unique method for inhibiting blood flow from the penis is indicated by the division of the cavernous veins into smaller channels prior to joining the subtunical venous plexus. Erectile tissue in the bifid origins of the corpus spongiosum has abundant cavernous muscle, while in the remainder of the corpus spongiosum little smooth muscle lines the cavernous spaces. The cavernous spaces on either side of the urethra coalesce to form vessels, each of which communicates with cavernous spaces in the glans. In addition, a bypass of the glans is effected by communication of these vessels directly with the deep dorsal vein. The apparent absence of muscular pads in vessels of the spongiosum, the relative paucity of cavernous smooth muscle, and the ample venous drainage provided by the deep dorsal vein may account for the lack of a venous occlusive mechanism similar to that of the corpora cavernosa penis.     

Vasculature of the parotoid glands of four species of toads (bufonidae: bufo)

The parotoid glands of toads (Bufonidae) consist of large aggregations of granular glands located between the otic region of the skull and the scapular region. To determine the circulatory pattern of these glands, we perfused the vascular systems of Bufo alvarius, B. marinus, B. terrestris, and B. valliceps with either India ink or Microfil, a fine latex. The perfused glands were studied by gross dissection, microscopic examination, and histology. The vascular patterns of the parotoid glands were compared to the arrangement of vessels in the dorsal skin of Rana sphenocephala (Ranidae), a frog that lacks parotoid glands. The parotoid glands of the four species of toads are supplied with blood by the lateral and dorsal cutaneous arteries and are drained by one or more branches of the internal jugular vein. The dorsal cutaneous artery supplies most of the blood to the parotoid glands in B. terrestris and B. valliceps. In B. alvarius and B. marinus, both the lateral and dorsal cutaneous arteries serve major roles in the blood supply of the glands. These patterns of blood flow have not been described previously for parotoid glands and conflict with earlier accounts for B. alvarius and B. marinus. The arteries and veins associated with the parotoid glands of toads are present in R. sphenocephala, but are arranged differently. In R. sphenocephala, the lateral cutaneous artery supplies the dorsal and lateral skin posterior to the shoulder region, whereas the dorsal cutaneous artery supplies the skin of the shoulder region. In toads, both the lateral and dorsal cutaneous arteries supply the skin of the shoulder region and ramify into subcutaneous capillaries that surround the secretory units of the parotoid glands. Extensive vasculature presumably is important for delivering cholesterol and other precursor molecules to the parotoid glands, where those compounds are converted into toxins.     

The ultrastructure of the blood vessels of Branchiostoma lanceolatum (Pallas) (Cephalochordata)

Summary The ultrastructure of the blood vessels in the caudal region of Branchiostoma is described in specimens injected with indian ink. None of the vessels have endothelial cells delimiting the luminal surface. The vessels are delimited either by dense connective tissue or by the characteristic basement lamella underneath the basal lamina of the myocoelic epithelium. It is proposed that the main blood flow in the caudal region follows different pathways depending on the activity of the animal. During swimming the muscle activity of the caudal muscles may have the effect that more blood flows from the aorta to the myoseptal plexi and is drained to the caudal vessel. In the resting animal it is possible that the blood flow through the myosepta is insignificant, and that the caudal blood flow is more or less restricted to the direct connections between the aorta and the caudal vessel: the dorsoventral anastomosis and the segmental connecting vessels.Supported by a grant from the Danish Natural Science Research Council     

A THREE-DIMENSIONAL RECONSTRUCTION OF THE VASCULAR SYSTEM TO THE LODICULES,ANDROECIUM, AND GYNOECIUM OF A FERTILE FLORET OF PANICUM DICHOTOMIFLORUM (GRAMINEAE)

A three-dimensional reconstruction of a fertile floret stele of Panicum dichotomiflorum approaching anthesis was made by a new technique using superimposition of tracings of 80, 1-μm thick serial sections, cleared tracing film, and mounting adhesive. From a collateral bundle, which also served as the median trace to the fertile lemma, most of the vascular tissue branched adaxially and horizontally to become the sole vascular supply to the two lodicules, three stamens, and pistil. The xylem branched at a low level to form a broad and long vessel plexus. The phloem branched at a higher level to overlay the vessel plexus on the right and left with an arc of horizontal sieve tubes in a phloem plexus. Those sieve tubes and vessels which rose after branching from the horizontal plexi assumed a more vertical course in the floret stele. Traces to the right and left lodicules arose from the lower abaxial portions of the flanks of the floret stele. Vessels ascended vertically from the xylem plexus and passed through the phloem plexi and joined with the sieve tubes there to exit at the same level and become the right and left lodicule traces. The vascular tissues to the three filament traces arose from different higher levels of the stele. The sieve tubes for the median filament trace arose vertically from the abaxial side between but above the lodicule traces. At higher levels the sieve tubes for the lateral filaments rose from the horizontal arcs of the flanks of the stele and departed it tangentially. The vessels destined to the filament traces arose in the center of the floret stele from adaxial portions of the horizontal plexus, ascended between the arcs of phloem, exited the stele simultaneously above the phloem of the traces, and followed the courses of their respective sieve tubes. The adaxially displaced apex of the floret stele then contained the vascular tissue related to the pistil. All the sieve tubes and vessels of the floret stele were embedded in a matrix of intermediary cells. The peripheral intermediary cells associated with the vessel plexus were xylem transfer cells with pronounced wall ingrowths. At higher levels in the floret stele, intermediary cells in scattered locations near sieve tubes or vessels had less conspicuous wall ingrowths. No preferred orientation of transfer cells with any particular trace was noted.     

Gill microcirculation of the air-breathing climbing perch, Anabas testudineus (Bloch):relationships with the accessory respiratory organs and systemic circulation

The general macrocirculation and branchial microcirculation of the air-breathing climbing perch, Anabas testudineus, was examined by light and scanning electron microscopy of vascular corrosion replicas. The ventral aorta arises from the heart as a short vessel that immediately bifurcates into a dorsal and a ventral branch. The ventral branch distributes blood to gill arches 1 and 2, the dorsal branch to arches 3 and 4. The vascular organization of arches 1 and 2 is similar to that described for aquatic breathing teleosts. The respiratory lamellae are well developed but lack a continuous inner marginal channel. The filaments contain an extensive nutritive and interlamellar network; the latter traverses the filament between, but in register with, the inner lamellar margins. Numerous small, tortuous vessels arise from the efferent filamental and branchial arteries and anastomose with each other to form the nutrient supply for the filament, adductor muscles, and arch supportive tissues. The efferent branchial arteries of arches 1 and 2 supply the accessory air-breathing organs. Arches 3 and 4 are modified to serve primarily as large-bore shunts between the dorsal branch of the ventral aorta and the dorsal aorta. In many filaments from arches 3 and 4, the respiratory lamellae are condensed and have only 1-3 large channels. In some instances in arch 4, shunt vessels arise from the afferent branchial artery and connect directly with the efferent filamental artery. The filamental nutrient and interlamellar systems are poorly developed or absent. The respiratory and systemic pathways in Anabas are arranged in parallel. Blood flows from the ventral branch of the ventral aorta, through gill arches 1 and 2, into the accessory respiratory organs, and then returns to the heart. Blood, after entering the dorsal branch of the ventral aorta, passes through gill arches 3 and 4 and proceeds to the systemic circulation. This arrangement optimizes oxygen delivery to the tissues and minimizes intravascular pressure in the branchial and air-breathing organs. The efficiency of this system is limited by the mixing of respiratory and systemic venous blood at the heart.     

Cholinergic and adrenergic innervation of the arteries of the base of the brain in certain lower vertebrates]

The arteries in the encephalon base have been investigated by Koelle's and Falck's methods in Teleostei (Anarhichas lupus, Eleginus navaga, Leuciscus brandti, Pelingas), amphibians (Rana temporaria, Rana semiplicata, Bufo bufo) and in reptiles (Testudo horsfieldi, Trionyx chinensis). Cholin- and adrenergic nerve fibres of the encephalic arteries have been revealed in all the vertebrates studied, but their concentration is far from being equal. In fishes and reptiles neural conductors from scarse plexus with wide loops. Concentration of effector neural fibres only in Bufo bufo exceeds that of fishes. In some cases, the arteries of frogs have equal or less density of cholin- and adrenergic neural conductors as compared with those of Pelingas. Certain individual peculiarities are noted in distribution of the effector neural fibres of the encephalic arteries of the vertebrates. In reptiles, the neural apparatus of the encephalic blood vessels reaches a considerable development; it is definitely differentiated into two plexuses - superficial and deep, having a close interconnection. The development of the effector vascular plexus in vertebrates corresponds to increasing mass of the brain and the vascular diameters. Taking into consideration structural peculiarities of the neural conductors and their concentration, it should be recognized that the role of the neural factor in regulation of the cerebral circulation increases in the following order: fishes - amphibians - reptiles.     

Angiosomes of the brachial plexus: an anatomical study

This anatomical study analyzed the neurovascular relationships of the brachial plexus. Ten fresh cadaveric brachial plexuses were examined after injection of the arterial system. The vascular anatomical features of the brachial plexus were documented with microdissection after lead oxide/gelatin injection. The specimens were analyzed by using radiography (including digital subtraction techniques) and light-microscopic, macroscopic, and digital photography. Four angiosomes, based on the subclavian, axillary, vertebral, and dorsal scapular arteries, were observed. As noted in previous angiosome studies, connections between angiosome territories lay within tissues, in this case, nerve trunks. Nutrient vessels penetrated nerve trunks at points of branching within the brachial plexus, with a Y-shaped mode of division on entry. The vascular supply was markedly rich, often with true anastomotic connections occurring within the nerves. There was much variation in supply, depending on the vascular anatomical features of the subclavian artery.     

Study of innervation of the pancreatic duct of Lepus europaeus, using the cholinesterase technique

The innervation of the pancreatic duct was studied in the European Hare (Lepus europaeus) by the cholinesterase technique. The duct was accompanied by thick myelinated and thin non-myelinated nerve fibres, which subsequently formed a plexi. The plexi were associated with the fibres of the plexi of the islet of Langerhans, or with ganglia, blood vessels or neural networks. No chain of ganglia was observed on or near the duct and the ductules.     

Ultrastructure of the Neurohypophysial Lobe of the Hagfish,Eptatretus stouti (Cyclostomata)

The neurohypophysial lobe is a thin-walled sac that, except for a few blood vessels, lacks any anatomical link with the adenohypophysis. Its wall consists of ependymal, fiber and palisade zones and is surrounded by blood vessels. The lobe is differentiated into distinct dorsal and ventral regions. The dorsal wall is doubly innervated by Gomori-positive axons arising in the anterior hypothalamus and by Gomori-negative fibers of unknown origin. Its surface is covered by an extensive vascular plexus. The ventral wall is innervated only by Gomori-negative fibers and is sparsely supplied with a few fine capillaries. All of the ependymal cells in both regions have the same ultrastructural appearance. The Gomori-positive or Type I axons are identified at the electron microscope level as fibers containing elementary granules with a diameter of 150–230 run. The Gomori-negative or Type II fibers contain dense-cored vesicles that vary from 80–125 nm in diameter. Both Type I and II fibers form synaptic-like complexes with the processes and end-feet of the ependymal cells. Type I axons also abut on the basal lamina bounding the perivascular spaces. It is suggested that the agranular reticulum of the ependymal cells may provide a transport pathway for neural products that are destined for release into the circulation. It is also possible that the ependyma itself is a target of neural activity.     

豚鼠小肠粘膜下层内神经节丛与血管的伴行现象

本文应用NADH黄递酶联合Karnovsky-Roots乙酰胆碱酯酶组化技术研究了豚鼠小肠粘膜下层铺片上神经节丛与血管的关系,结果发现,由肌层穿入粘膜下层的小动、静脉及其分支互相伴行,环绕肠壁;动、静脉两侧有大致平行走向的伴行神经节丛,并从伴行的神经节丛发出分支终止于动、静脉壁上以及连接动、静脉两侧的神经节丛之间有纤维束相连。这种伴行现象在小动、静脉起始段和第一级分支段最为明显。伴行的神经节多数呈长梭形,其长轴与血管长轴平行。在血管“人”字形分支处,可见到“人”字形神经节,常位于静脉叉内。上述结果提示,伴行的神经节丛可能调节粘膜下层和粘膜的血流,从而影响小肠的吸收功能。     

Vascularization of the pituitary of the Australian lungfish and Neoceratodus forsteri

The vascularization of the brain and the pituitary region of the Australian lungfish, Neoceratodus forsteri is described from serial section reconstruction. The distal lobe has no direct arterial blood supply and receives blood solely from a pituitary portal system basically similar to that of other sarcopterygians. The primary capillary plexus of the median eminence receives its arterial blood from the infundibular arteries, which on their way distribute some small branches to the prechiasmatic region. The primary plexus also receives capillaries from the adjacent pial hypothalamic plexus. The primary capillary plexus of the median eminence comprises a rostral 'uncovered' and caudal 'covered' part which are not sharply delineated. Distinct portal vessels connect the 'uncovered' rostral part of the primary plexus with the secondary capillary plexus supplying the rostral subdivision of the pars distalis. The 'covered' caudal part of the primary plexus merges into the proximal subdivision of the pars distalis, apparently without formation of distinct portal vessels. The primary plexus has some connections with the plexus intermedius via a hypophysial stem capillary plexus. The plexus intermedius has a substantial arterial supply and gives off capillaries to the parenchyma of the pars intermedia. The adenohypophysis is drained into an unpaired hypophysial vein. The significance of the vascular pathways is discussed from comparative, functional, and evolutionary viewpoints.     

Nerves and nerve plexuses of the human vertebral column

The origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole-mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu-vertebral nerves. The sinu-vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu-vertebral nerves are found. Most frequently three types of thick sinu-vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu-vertebral nerves is described.     

The atrioventricular branches of the human coronary arteries

Branches of the coronary arteries of normal human hearts, supplying both atria and ventricles, were found by fine dissection and have been named rami atrioventriculares. They comprise atrial branches from ventricular arteries and ventricular branches from atrial arteries. Their incidence was 74% in the 50 adult individuals studied. The subjects had committed suicide with a poison which did not damage the coronary arteries. The atrioventricular branches constitute communications across the coronary sulcus, thus establishing a continuity between the atrial and the ventricular arterial supply. Therefore, there is not invariably a sharp demarcation of blood supply between atria and ventricles, as has been commonly taught. Neither atrial nor ventricular branches consist exclusively of ascending and descending branches of the coronary arteries, as has been assumed. Atrioventricular branches can play a role in collateral circulation and may, in individuals who are born with them, provide an explanation for some of the variability in signs and symptoms incidental to heart attacks.     

Blood collection from the facial (maxillary)/musculo-cutaneous vein in true frogs (family Ranidae)

Collection of blood from amphibians, as in other classes of vertebrate animals, is essential to evaluate parameters of health, diagnose hemoparasitism, identify viral and bacterial pathogens, and measure antibodies. Various methods of blood collection have been described for amphibians. Most can be cumbersome (venipucture of femoral vein, ventral abdominal vein or lingual venus plexus) or result in pain or deleterious health consequences (cardiac puncture and toe-clipping). We describe an easy and practical technique to collect blood from frogs and toads that can be used in multiple species and is minimally invasive. The technique consists of puncturing either the facial or, less commonly, the musculo-cutaneous vein and collecting the blood with a capillary tube. These veins run dorsal and parallel to the maxillary bone and can be accessed by quick insertion and withdrawal of a needle through the skin between the upper jawline and the rostral or caudal side of the tympanum. The needle should be of 27 or 30 gauge for anurans weighing more or less than 25 g, respectively. Although the technique has been used by some amphibian researchers for years, it is little known by others and has never been fully described in a peer-reviewed publication.