Das Blutgefäßsystem des Enddarms vom Hund (Canis lupus f. familiaris)

The Vascular System in the Large Intestine of Dog (Canis lupus f. familiaris) The vascular System of the large intestine of 10 dogs was examined by means of vascular corrosion casts, histology and transmission-electron microscopy. The tela submucosa contains an arterial and a venous vascular plexus. In broader areas of the submucosa, a deep and a superficial vascular plexus, which are interconnected, can be found. The plexus are orientated parallel to the layers of the intestinal wall. On the one hand, these vessels naturally provide self-sufficiency and drainage of the submucosa, and, moreover, direct branches to the stratum circulare of the muscular layer. On the other hand, the submucosal vascular plexus is the ‘distributional network’ for the functional plexus of the tunica mucosa. The arteries, which ascend to the tunica mucosa, supply a flat arterial network underneath the intestinal glands. Bundles of only a few arteriolae originate from this in order to supply the pericryptal capillaries. In the vicinity of the cryptai orifices, these turn into a network of subepithelial capillaries, which is post-connected to the periglandular capillary plexus. From this ‘terminal circulatory pathway’, the blood is drained off by veins that enter the submucosal plexus. It is characteristic that the postcapillary venules often begin as part of the capillary network. As in other species, the subepithelial capillaries are predominantly lined with a ‘fenestrated endothelium’, whereas the capillaries of the pericryptal areas show a continuous endothelium. The latter contains multiple vesicles that may fuse in order to form transcytoplasmic channels as a morphological equivalent for transcappillar-epithelial and vice versa occurring transport of substances.     

Über die intramuralen Blutgefäße des Enddarms vom Pferd (Equus przewalskii f. caballus)

The vascular system of the large intestine of 12 horses was examined by means of vascular corrosion casts, histology and transmission electron microscopy providing the following results. The Aa. et Vv. breves et longae leave the mesenteric vessels, respectively the subserously on the teniae lying cecal vessels to reach the tela subserosa at the mesenteric margin. The short vessels enter the deeper layers of the wall instantly, whereas the Aa. et Vv. longae move towards the submucosa by penetrating the muscular layers after a variable subserous course. The tela submucosa contains an arterial and a venous vascular plexus. In broader areas of the submucosa a three-dimensional vascular network can be found. This consists of a deep and a superficial vascular plexus, which are closely interconnected. The deep plexus is applied to the inner circular muscles, whereas the superficial plexus is adjacent to the muscularis mucosae. The (deep) arterial plexus receives its afflux from the Aa. breves et longae and supplies parts of the circular muscle layer with recurrent muscle branches. The vascularisation of the mucosa also originates from the submucosal (superficial) plexus. In the basal tunica mucosa, the ascending arteries form a transversal network from which arterioles branch into periglandular capillaries around each Lieberkühn crypt. Close to the lumen, a polygonal subepithelial capillary system is formed. The capillaries turn into postcapillary venules immediately below the epithelium of the mucosal surface. Veins move vertically through the submucosa to enter the submucosal plexus after few inflowing side branches. Branches of the subserous-submucosal connections form an intermuscular plexus between the circular and longitudinal muscular layer. This plexus supplies the capillaries of the tunica muscularis. The subepithelial capillaries are predominantly lined with a fenestrated endothelium, whereas the capillaries of the pericryptal mucosa mainly show a continuous endothelial lining. The latter contain multiple vesicles, which may fuse in order to form transcytoplasmic channels. Sphincter-like muscle bundles at the transition points from capillaries to venules may provide hemodynamic regulatory structures in the submucosa of the horse. Veins with circumferential cushions of smooth muscle fibres, so-called ‘throttle veins’, are also found.     

Das Blutgefäßsystem des Enddarms vom Schwein (Sus scrofa f. domestica)

The circulatory system of the large intestine of 27 pigs was examined by means of corrosion anatomy (vascular casts), histology and electron microscopy. The results were as follows: The Aa. et Vv. breves et longae leave the mesenteric vessels and reach the wall of the intestine at the mesenteric margin. The short vessels enter the deeper layers of the wall, whereas the Aa. et Vv. longae, by taking a variable subserous course, reach the submucosa af ter penetrating the muscular layers. The tela submucosa contains an arterial and a venous vascular plexus. Where the submucosa is larger, there is a three-dimensional vascular network, a deep and superficial vascular plexus that are closely interconnected. The deep plexus is applied to the inner circular muscles, whereas the superficial plexus is adjacent to the muscularis mucosae. The deep arterial plexus receives its af flux from the Aa. breves et longae and provides part of the circular muscle layers with recurrent muscle branches. The vascularization of the mucosa is derived from the (superficial) submucosal plexus. The arteries that ascend the tunica mucosa ramify, in the form of a brush, into some arterioles. In the basal part of the mucosa, they turn into a periglandular capillary system, i.e. a network around each Lieberkühn crypt. Close to the lumen, a polygonal subepithelial capillary system is formed. Below the epithelium of the mucosal surf ace, the capillaries turn into postcapillary venules. These are running vertically through the submucosa, with few infiowing side branches, and finally enter the submucosal plexus. An intermuscular plexus is formed by anastomoses between the circular and the longitudinal muscular layers from the branches of the subserous-submucosal connections. This intermuscular plexus provides the capillaries for the tunica muscularis. The subepithelial capillaries are, above all, furnished with a so-called fenestrated endothelium, whereas the capillaries of the pericryptal mucosa mainly show a continuous endothelium. The latter contains multiple vesicles that can fuse to form transcytoplasmic channels. In the wall of the large intestine of the pig, there are no sure indications as to the existence of either arterio-venous anastomoses or haemodynamic regulatory structures.     

Das Blutgefäßsystem der Magenwand der Katze*

The blood vascular system of the stomach wall in the cat The results of 19 vascular-injections of the stomach wall in the cat are given. The arterial supply to the parietal surface is derived principally from the left gastric artery, that of the visceral surface from the short gastric branches of the splenic artery. Thus the arterial distribution is similar to the venous drainage. The blood supply of the tunica serosa and the tunica muscularis in the fornix and body regions arises from a common subserosal and muscular plexus. In the pyloric canal the blood supply arises from separate subserosal and intermuscular plexus. The submucosal plexus consists of both arteries and veins: from this, mucosal arteries ascend to a subglandular plexus and thence arterioles supply the capillary plexus of the lamina propria. Venules return the blood through collecting veins to a basal venous plexus, thence through mucosal veins to the submucosal plexus.     

Microvascular circulation of the small intestine in horses.

The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfused with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. The marginal arterial arcade gives rise to vessels that enter the jejunum at the mesenteric angle. These vessels penetrated either directly, by branching and entering on both sides of the mesenteric angle, or supplying only 1 side of the mesenteric angle. All these vessels continued in the submucosa branching extensively, forming a submucosal plexus. This submucosal plexus supplied the tunica muscularis, tunica serosa, and the mucosa. Vessels within the 2 muscle layers ran parallel to the muscle fibers and, consequently, perpendicular to each other. The arterial supply to the mucosa penetrated the muscularis mucosae and branched to supply 2 mucosal capillary networks. An eccentrically placed arteriole penetrated the base of the villus and spiralled to the tip where it "fountained" into a mesh-like capillary network, which descended peripherally in the villus to drain via 1 to 3, but most commonly 2 venules. Venules from adjacent villi united and drained via the submucosal veins.(ABSTRACT TRUNCATED AT 250 WORDS)     

Observations on the Equine Hypophysial Portal System

The blood supply to the equine pituitary gland, with special attention to its portal system, was studied by the aid of vascular injections and histological serial sections. The primary capillary plexus of the median eminence was supplied by the rostroventral and rostrodorsal infundibular arteries, which were branches of the internal carotid arteries and the ramus communicans caudalis, respectively. The neural lobe was supplied by the caudal infundibular arteries, which originated from the arteria intercarotica caudalis. Dorsal and ventral groups of the portal vessels were described. Their regional distribution into the sinusoidal capillaries of the pars distalis was discussed. Results of this investigation indicated that the portal vessels were the sole supply to the equine pars distalis. No direct arterial supply to this part of the adenohypophysis was observed.     

A scanning electron microscopical study of the dermal microcirculation of the equine foot

The microcirculation of the dermal laminae and papillae of the equine foot from seven clinically normal Australian ponies was studied using an improved microvascular casting corrosion technique and scanning electron microscopy. Casts of veins, arteries, capillaries and arteriovenous anastomoses (AVAs) were readily identified by their characteristic surface morphology. Arteries entered the laminar circulation axially, between pairs of axial veins, and were connected to each other by smaller calibre interconnecting arteries. Short abaxial branches of the axial interconnecting arteries gave rise to tufts of predominantly, proximodistally orientated, capillaries arranged abaxially in rows. The laminar veins anastomosed with each other extensively (the axial venous plexus) and formed most of the vascular skeleton of casts of the dermal laminae. AVAs were found throughout the laminar circulation but the largest and longest (40 mu diameter) were found clustered close to the origin of the axial arteries. The density of the laminar AVAs was estimated to be 500 AVAs/cm2. Blood vessels of the dermal papillae of the periople, coronary band, distal laminae, sole and frog shared a basic structural organisation. The cast of each papillary unit consisted of a central artery and vein enmeshed in a sheath of fine capillaries. At intervals along the length of the central artery were short branches which gave rise to tufts of capillaries. The capillaries formed a tortuous anastomosing plexus which encircled the papillary unit and drained into the central vein at intervals along its length. AVAs were always present at the base of the papillary units and anastomoses connected the central artery and vein. AVAs are important components of the dermal microcirculation of the equine foot and their distribution and density is compatible with their proposed role in the pathophysiology of equine laminitis.     

Microvascular anatomy of the pig eye: scanning electron microscopy of vascular corrosion casts

The microvasculature of the eye of 10 pigs was investigated using scanning electron micrographs of corrosion casts. The ciliary body, iris and bulbar conjunctiva were supplied by the iridociliary ring artery via the long posterior ciliary artery. Capillaries of the ciliary process were of large diameter (23.2-27.5 microm) with an irregular bore, forming a thoroughfare channel draining blood in the ciliary arterioles into the pars plana venous vessels. Arterioles and venules in the iris exhibited a zigzag or spiral features. The third palpebra was supplied by the anterior ciliary artery. The capillary bed of the third palpebra was dense and was formed by many rows of fine hair-pin loops. Capillaries in the bulbar conjunctiva formed a sparse network disposing approximately parallel to the epithelium and formed a well-developed venous plexus, draining into the vortex veins. Retinal arterioles formed a slender and long course to capillaries. Retinal capillaries were extremely thin (3.0-4.0 microm in diameter). The choroid was supplied by the short posterior ciliary arteries. Choroidal arterioles exhibited a thick and short course to the choriocapillaris. The choriocapillaris was flat and sinusoid-like (8.9-13.9 microm in diameter), forming a dense sheet-like network. Blood from the choroid emptied into the episcleral vein via the vortex vein. Blood from the retina was drained by the posterior ciliary veins. The functional significance of this vascular architecture was discussed.     

Microvasculature of the hamster eye: scanning electron microscopy of vascular corrosion casts

The architecture of the retina, choroid and anterior eye segment was investigated in 12 Syrian hamsters using scanning electron micrographs of methylmethacrylate corrosion casts. The hamster eye receives its primary blood supply from the long posterior ciliary artery, which directly enters the optic nerve head, and divides into three branches: the central retinal artery and medial and lateral long posterior ciliary arteries. In the retina the central retinal artery divides into six radiating branches. Retinal arterioles form a slender and long course to capillaries. Retinal capillaries are extremely thin in diameter and form a sparse capillary network. The choroid is supplied by the long posterior ciliary arteries. Choroidal arterioles exhibit a thick and short course to the choriocapillaris. The choriocapillaris is thick and sinusoid-like, forming a dense network in the choroid. The ciliary body, iris and bulbar conjunctiva are supplied by the anterior ciliary arteries, which are branches of the long posterior ciliary arteries. Capillaries supplying the anterior margin of the ciliary process are large in diameter with an irregular bore, forming a thoroughfare channel draining blood in the ciliary arterioles into the pars plana vessels. Blood from the retina is drained by the central retinal veins. Venules from the anterior eye segment empty into the vortex veins via the pars plana vessels. Venous blood from the choroid is drained only by vortex veins via the choroidal veins. The functional significance of the vascular architecture and species differences are discussed.     

Intestinal fibrosis with partial obstruction in five horses and two ponies.

Fibrosis of the small intestine led to recurrent colic and weight loss in 2 ponies and 5 horses. There was a reduction in the length of the small intestine to one-half normal in horses 4 to 7. Histologic examination revealed substantial small intestinal submucosal fibrosis and arteriole sclerosis. The cause was not determined, but an environmental factor was suspected because 3 horses were from the same farm and the other animals were from within a 10-mile radius of the farm. The submucosal fibrosis appeared to be secondary to sclerosis of arterioles in the submucosa and mesentery, with low blood flow state or altered vessel permeability.     

Microvascular circulation of the descending colon in horses.

The microvascular circulation of the descending colon was studied in 5 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, horses were euthanatized, and 3 segments of the descending colon and its mesentery containing 1 vascular arcade were removed from each horse. The fecal balls were gently massaged from the lumen, and the blood was flushed free of the circulation with isotonic NaCl. In 5 segments, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Specimens examined radiographically also were prepared for histologic examination, using standard methods. Ten segments were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. Arcuate arteries gave rise to a descending colonic rete that surrounded the vein and supplied numerous descending colonic lymph nodes. The rete also supplied the mesocolon and the descending colonic tissue. Short filamentous vessels arising from the rete directly penetrated the mesenteric tenia to supply an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. Larger vessels arising from either side of the rete divided into the long- and short-terminal arteries that supplied an extensive submucosal plexus, which was continuous around the circumference. The submucosal plexus supplied the mucosa, the tunica muscularis, and the serosa. Vessels running centrifugally from the submucosal plexus formed an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. The intermuscular plexus at the mesenteric angle also was supplied by vessels branching from the short-terminal arteries as they penetrated the muscularis externa.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microvasculature of the medulla oblongata in the Lyle's flying fox (Pteropus lylei)

The microvasculature of the medulla oblongata in 15 adult Lyle's flying foxes (Pteropus lylei) was elucidated by using the vascular corrosion cast technique combined with scanning electron microscopy. The study showed that the medulla received the main arterial supply from branches of the vertebrobasilar system. The supplied areas were divided into three groups: ventral, lateral and dorsal groups. All vessel groups gave off circumferential and perforating branches; moreover, these branches anastomosed with one another in two fashions: end-to-end and side-by-side arrangements. In addition, the ramifications of the branches were L and Y types. The L type was more frequently found than the Y one. The density of capillaries in the nuclei was greater than that in the area of nerve fibres. Numerous arterial sphincters and smooth muscle cells were observed. Furthermore, capillaries in the medulla were of the continuous type, whereas those in the area postrema were fenestrated. The venous drainage system of the medulla was classified into caudal, middle and rostral parts. All of them emptied into both the sigmoid sinus and internal jugular vein. It was concluded that these vascular patterns provide sufficient blood supply to the medulla oblongata of P. lylei when abrupt changes in the position of this bat occurs.     

Microvascular architecture of the near-term uterine caruncles in water buffaloes (Bubalus bubalis)

The present investigation was carried out on five near-term pregnant water buffaloes for studying the microvascular architecture of the uterine caruncles. The vascular casts were obtained by injection of 4:1 mixture of mercox and methylmethacrylate through the branches of the uterine arteries. After complete polymerization of the plastic, corrosion was conducted in 20% potassium hydroxide, then the vessel casts were immersed in distilled water, cut into small pieces, sputter coated with gold, and examined by using a scanning electron microscope. The buffalo uterine caruncle is highly vascularized through two slightly convoluted arteries and a single less tortuous vein. The arteries branch into several stem arteries at the base of the uterine caruncle, which follow nearly straight course in the primary septa towards the fetal side. During the courses of these stem arteries arterioles of variable diameters arise. The arterioles run in the secondary and tertiary septae and at this location arterioles and venules are connected through a voluminous capillary complex. The latter consists of capillaries of greatly variable diameters with vigorous coiling and sinusoidally dilated zones. From the capillary complexes the blood is driven through postcapillary venules back to the tertiary, secondary and primary septa, respectively, and then converge into stem veins which leave the caruncles through the branches of the uterine vein.     

Microvascular circulation of the ascending colon in horses

Microvascular circulation of the ascending colon in healthy horses was studied using microangiography, light microscopy, and scanning electron microscopy. The pelvic flexure with 30 cm of ventral and dorsal colon attached was removed from 14 adult horses immediately after horses were euthanatized. The lumen was flushed with warm water, and this section of the ascending colon was placed in a 37-C bath of isotonic NaCl. In sections from 8 horses, colic vessels were perfused with a radio-opaque medium for microangiography. After angiographic evaluation, tissue sections were prepared for light microscopic observation, using standard histologic methods. In sections from 6 horses, injection replicas were made by perfusing the vessels with 2 types of plastics. The results of microangiography, light microscopy, and scanning electron microscopy of vascular replicas were correlated, providing a comprehensive documentation of the microvasculature of the ascending colon at the pelvic flexure. Arteries branched from mesenteric colic vessels approximately every 2 cm toward the colonic tissue. Immediately after branching, arterial vessels formed an anastomotic plexus, the colonic rete. However, each branch from the colic vessel eventually continued into the colonic tissue. A second set of vessels originated from the colonic tissue. A second set of vessels originated from the colonic rete and supplied the mesenteric lymph nodes. Arterial vessels penetrated the tunica muscularis into the submucosa 3 to 4 cm toward the antimesenteric border forming a submucosal vascular network. From the submucosal arterioles, branching took place at right angles to supply the mucosal capillaries. Capillaries surrounded the colonic glands and anastomosed at the luminal surface, forming a superficial luminal honeycomb-appearing vascular plexus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sur la Microvascularisation des Plexus Choroïdes des Ventricules Latéraux chez la Chèvre (Capra hircus)

The goat choroid plexus angioarchitecture of the lateral ventricles was studied under the SEM using the method of “microvascular corrosion casts”. The whole plexus is semilunar shaped and directed in an antero-posterior, latero-median fashion. In the plexus the lateral extremity is larger than the median one. All the components of the vascular bed (arteries, venes and capillaries) of the choroid plexus have interesting morpho-structural features. In particular, the capillaries are more developed than the other components and they are variously located on both sides of the plexus. The capillary network has a various organization in different zones of each side of the plexus.     

Early mucosal healing and chronic changes in pony jejunum after various types of strangulation obstruction

Strangulation obstruction was induced in anesthetized ponies for periods of 2 and 3 hours by clamping 45-cm segments of jejunum and their veins only (venous strangulation obstruction, VSO) and arteries and veins (arterial and venous strangulation obstruction, AVSO). These types of strangulation obstruction were studied in 4 segments in each of 4 ponies allowed to survive 12 hours (group 1) and in a single segment in each of 10 ponies allowed to survive 42 days (group 2) after the strangulation period ended. On visual inspection, segments subjected to VSO had hemorrhage and edema in the bowel wall and mesentery and were dark purple after all time intervals. They improved slowly after clamps were removed, but remained hemorrhagic and edematous. Segments subjected to AVSO were purple and had mild edema and scattered petechiae in the bowel wall and mesentery. They improved rapidly and closely resembled normal bowel after 5 minutes of reperfusion. On light and scanning electron microscopy, the mucosa of intestine subjected to VSO and AVSO had necrotic, denuded villi 1 hour after the strangulation periods ended. Twelve hours after removal of occlusion devices in group-1 ponies, 4 (25%) segments were unchanged, 4 (25%) had deteriorated, and 8 (50%) had stunted villus remnants partly or completely lined with regenerating epithelium. Separation and detachment of villus tip mucosal cells were seen in 3 of 4 control segments, 1 and 12 hours after the strangulation periods ended.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microvascular circulation of the cecum in horses

The microvascular circulation of the cecum was studied in 15 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, the horses were euthanatized and the cecum was transected at the cecocolic junction. Blood was flushed free of the circulation with isotonic NaCl and the cecal lumen was slightly distended. In 6 horses, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Sections evaluated radiographically were also prepared for histologic examination by standard methods. Eight horses were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. In 1 additional horse, the lateral and medial arteries were injected with different colored plastic for gross studies. The lateral and medial cecal arteries appear to supply the respective areas of the cecum with minimal mixing of the 2 circulations. The major vascular supply to the cecal apex appeared to be through the medial cecal artery. Both the lateral and medial cecal arteries gave rise to cecal retia, which formed a mesh-like network around the respective veins. Vessels from these retia supplied the cecal tissue and the cecal lymph nodes. The continuation of the retia was through long terminal arteries that coursed around the circumference in the submucosa, forming an extensive submucosal plexus. This plexus supplied both the mucosa, and the tunica muscularis and serosa. Vessels within the longitudinal and circular muscle layers of the muscularis externa ran parallel to the muscle fibers, and consequently, perpendicular to each other.(ABSTRACT TRUNCATED AT 250 WORDS)     

Triple‐phased mesenteric CT angiography using a test bolus technique for evaluation of the mesenteric vasculature and small intestinal wall contrast enhancement in dogs

Computed tomography angiography is widely used for the assessment of various mesenteric vascular and bowel diseases in humans. However, there are only few studies that describe CT angiography application to mesenteric vessels in dogs. In this prospective, experimental, exploratory study, the mesenteric vasculature and enhancement pattern of the intestinal wall were evaluated on triple‐phase CT angiography, and improvement of the visibility of vasculature was assessed on multiplanar reformation, maximum intensity projection, and volume rendering technique. After test bolus scanning at the level of the cranial mesenteric artery arising from the aorta, mesenteric CT angiography was performed in 10 healthy, male, Beagle dogs. Scan delay was set based on time‐to‐attenuation curves, drawn by placing the regions of interest over the aorta, intestinal wall, and cranial mesenteric vein. Visualization and enhancement of mesenteric arteries and veins were evaluated with multiplanar reformation, maximum intensity projection, and volume rendering techniques. The degree of intestinal wall enhancement was assessed on the transverse images in precontrast, arterial, intestinal, and venous phases. Pure arterial images were obtained in the arterial phase. Venous phase images allowed good portal vascular mapping. All CT angiography images were of high quality, allowing for excellent visualization of the anatomy of mesenteric vasculature including the small branches, particularly on maximum intensity projection and volume rendering technique. Distinct contrast enhancement of the intestinal wall was observed in both intestinal and venous phases. Findings indicated that this technique is feasible for the evaluation of mesenteric circulation in dogs.     

Microvascular anatomy of ovary and oviduct in the adult African Clawed Toad (Xenopus laevis DAUDIN, 1802)–Histomorphology and scanning electron microscopy of vascular corrosion casts

Ovaries and oviducts of the adult African Clawed Toad (Xenopus laevis DAUDIN, 1802) were studied by light microscopy (LM) of paraplast embedded tissue sections and scanning electron microscopy (SEM) of vascular corrosion casts (VCCs). Histomorphology revealed that ovarian vessels located in the thecal layers. Ovarian and interlobar arteries displayed a horse-shoe shaped longitudinally running bundle of vascular smooth muscle cells. Follicular blood vessels showed flattened profiles, which were confirmed by scanning electron microscopy in vascular corrosion casts. The flattened profiles obviously led to high intravasal pressures, which locally prevented filling of the follicular capillary bed. Oviduct arteries pierced the fibrous stroma surrounding the oviduct mucosa. In the pars convoluta, the mucosa consisted of a ciliated simple columnar epithelium and tubular oviduct glands that opened between ciliated epithelial cells into the oviduct lumen. Oviduct arteries branched at the basolateral surfaces of tubular glands. After a short tangential course, arterioles branched into capillaries which ran radially between oviduct glands towards the subepithelium. Anastomoses at different heights connected capillaries of neighbouring glands. Subepithelially, capillaries ran longitudinally and undulated. Postcapillary venules radiated centrifugally towards the stroma to finally drain into oviduct veins located in the stroma. Oviduct vascular densities clearly reflected non-ovulatory and ovulatory states.