Does primary urethral realignment improve the outcome of pediatric pelvic fracture urethral injury? A randomized controlled trial

OBJECTIVE

To assess the efficacy of primary urethral realignment in the prevention of urethral stenosis and in simplifying delayed urethroplasty after complete pelvic fracture urethral injury in male children.

METHODS

This randomized comparative trial included 40 boys <18 years with complete pelvic fracture urethral injury. The initial management was a primary urethral realignment in 20 boys and suprapubic cystostomy alone in the remaining 20 boys. The boys who underwent primary urethral realignment were assessed regarding the development of urethral stenosis. Boys who needed to be delayed urethroplasty in the two groups were compared regarding urethral defect length, intraoperative details, postoperative outcomes, number of procedures, and time to achieve normal voiding.

RESULTS

Although 14 (70%) patients were able to void after primary urethral realignment, all of them developed urethral stenosis and needed delayed urethroplasty. No statistically significant difference between the two groups was found regarding urethral defect length, intraoperative details, and postoperative outcomes. Patients in the primary urethral realignment group underwent significantly more procedures (p < 0.001) and took a significantly longer time to achieve normal voiding (p = 0.002).

CONCLUSION

Primary urethral realignment is neither able to prevent urethral stenosis nor effective in simplifying later urethroplasty after complete pelvic fracture urethral injury in male children. It exposes the patients to more surgical procedures and a prolonged clinical course.

Flavonoids of Chromolaena odorata (L.) R.M.King & H.Rob. as potential leads for treatment against tuberculosis

Tuberculosis (TB) is currently rated as the 13th leading cause of mortality and the second leading cause of death after COVID-19, and above AIDS. Existing challenges relating to the development of multidrug-resistant strains and dangerous side effects of currently used drugs add impetus to the search for additional TB treatments. Hence, interest has grown in the use of medicinal plants as a source of bioactive preparations with efficacy against TB-causing organisms, and also with the ability to ameliorate the negative effects of TB drugs. This study aimed to evaluate the antimycobacterial and hepatoprotective potentials of extracts and isolated flavonoid compounds from invasive Chromolaena odorata. Test organisms used were pathogenic Mycobacterium bovis and M. tuberculosis H37RV, and the fast-growing M. aurum, M. fortuitum and M. smegmatis. The selectivity index (SI) values of the test substances were determined through cytotoxicity assays to promote these extracts and compounds as leads for the development of effective and safe anti-tubercular drugs. The antimycobacterial activity was evaluated using a serial microdilution method, and the SI was calculated from the 50% lethal concentrations calculated from cytotoxicity tests. Hepatoprotective activity was determined using HepG2 liver cells treated with rifampicin as a toxin. The extracts and compounds had a range of antimycobacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.031 to 2.5 mg/mL. Two flavonoid compounds, 5,7,4'-trimethoxy flavanone and 5‑hydroxy-3,7,4'-trimethoxyflavone showed promising antimycobacterial potential, and minimal toxicity was observed, as most SI values were higher than 1. The flavonoid compound 5,7,4'-trimethoxy flavanone had the highest SI (6.452), which was against M. tuberculosis H37RV. The HepG2 cells were reduced to 65% due to toxicity by rifampicin, however, the flavonoid compounds were able to improve cell viability to between 81 and 89% at different concentrations tested. Results obtained indicate that C. odorata may serve as a lead for the development of safe and effective antimycobacterial and hepatoprotective drugs.

The use of dynamic external fixation in the treatment of dorsal fracture subluxations and pilon fractures of finger proximal interphalangeal joints

The aim of this study was to review the outcome of the treatment of finger proximal interphalangeal joint dorsal fracture subluxations and pilon fractures with a modified external fixator. We treated 36 patients (36 fingers). We assessed the ranges of motion and patient satisfaction. At final follow-up, 23 patients had no pain; 11 had pain in the cold; and two also had mild pain. None had moderate or severe pain. The mean range of proximal interphalangeal joint motion was 86° (60°-100°). The mean total active range of finger motion was 244° (range 200°-265°). This system is simple, cheap and relatively easily applied. It gives stable fixation that allows early mobilization.

LEVEL OF EVIDENCE

IV.

Evaluation of early endoscopic realignment of post-traumatic complete posterior urethral rupture

Introduction:

to report our experience with 41 patients treated by early endoscopic realignment of complete post-traumatic rupture urethra.

Materials and Methods:

The study includes patients presented to our institute, between May 2004 and April 2009, with post-traumatic complete posterior urethral disruption. Preoperative retrograde urethrography, voiding cystourethrography and abdominopelvic CT were performed to evaluate the urethral defect length, the bladder neck competence, the prostate position, and the extent of the pelvic hematoma. Within the first week after trauma, antegrade and retrograde urethroscopy were performed to identify both urethral ends and insert urethral catheter. Patients were followed up by pericatheter retrograde urethrogram monthly postoperatively till catheter removal on disappearance of extravasation. Retrograde urethrography, voiding cystourethrography and urethroscopy were performed 1 month after the removal of the catheter. Follow-up abdominal ultrasound and uroflowmetry monthly till 6 months, bimonthly till 1 year, and every 3 months thereafter were encouraged. Urinary continence and postoperative erectile dysfunction were assessed by direct patient interview.

Results:

Forty one patients in the age group 17-61 years (mean 37.9) were treated. Patients were followed up for

Conclusions:

Early endoscopic realignment for complete posterior urethral rupture is a feasible technique with no or minimal intraoperative complications. The technique is successful as the definitive line of therapy in reasonable number of patients and seems to render further future interventions for inevitable urethral stricture easier.

Single puncture percutaneous nephrolithomy for management of complex renal stones

BACKGROUND

The purpose of this report is to assess the safety and efficacy of single lower pole access for multiple and branched renal calculi. A prospective non randomized clinical study included 26 patients with complex renal stones (9 patients had branched renal stones and the other 17 had multiple renal stones) in the period from May 2003 to May 2004. Mean patient age was 42 years +/- 13.2 (range 18 to 67 years). All patients underwent percutaneous nephrolithotomy (PCNL) via a single lower calyceal puncture. Small stones were intactly extracted by a range of stone graspers while large stones (smallest diameter more than 1 cm) were disintegrated using either the pneumatic EMS Swiss lithoclast or Holmium YAG laser. Flexible nephroscope was used for stones inaccessible by the rigid instruments.

FINDINGS

Overall stone-free rate was 74.8%. Patients with residual stones were managed by one session of shock wave lithotripsy (SWL). Mean operative time was (80 minutes +/- 27.4) for branched stones and (49.1 minutes +/- 15.9) for multiple stones. No significant blood loss reported. Perforation of pelvicalyceal system occurred in 2 patients (11.5%) with no serious sequelae. Only 1 patient developed secondary hemorrhage which necessitated blood transfusion and selective angio-embolization.

CONCLUSION

In our hands, the efficacy and safety of single lower calyceal puncture PCNL in management of complex renal stones are comparable to those of the general procedure stated in literature.

Visible spectrophotometric determination of cephalosporins and penicillins by indophenol derivatization with and without alkaline degradation to ammonia

Cephalosporins and penicillins give reproducible yields of ammonia on degradation in 0.5 M sodium hydroxide solution at 100 degrees C: the ammonia formed was determined in the degraded solutions using the indophenol reaction. In another approach the ammonia driven off on refluxing alkaline solutions of the cephalosporin or penicillin was collected in dilute hydrochloric acid solution and determined using the indophenol reaction. For eight of the fourteen cephalosporins and penicillins studied identical yields were recorded using the two procedures: these varied from 29% for penicillin G to 137% for cephalonium based on the production of one ammonia molecule per beta-lactam molecule. For six other cephalosporins the distillation method gave substantially higher yields of ammonia than did the direct determination. Eight cephalosporins and penicillins were found to give substantial indophenol-type reactions without prior hydrolysis of the beta-lactam, but the sensitivities were usually lower than for the hydrolysis method. Manual spectrophotometric procedures for the determination of cephalosporins and penicillins based on these reactions have been developed.

Ureteroscopic holmium laser lithotripsy in patients with renal impairment

OBJECTIVES

In this study, we try to evaluate the efficacy and safety of holmium lasers for treatment of ureteric stones in patients with renal impairment or obstructive anuria.

PATIENTS AND METHODS

Twenty-six patients were included in this study, of which 20 patients presented with elevated blood urea and serum creatinine (2.1-7.6 mg%), and six patients presented with calcular anuria (mean serum creatinine 22 mg%). None of the patients had a ureteric stent or nephrostomy tube before the ureteroscopy. All patients were treated with holmium laser. A stone basket or grasper was used to remove significant stone fragments at the end of the procedure in seven patients. In these seven patients, ureteric stents were placed at the end of the procedure.

RESULTS

All patients were free of any stone fragments at 1 week and at 3 months postoperatively. In all patients, including the six with obstructive anuria, the renal impairment resolved or improved as evidenced by normalization or fall in blood urea and creatinine. Thus, in this small group of uremic patients, the success rate for treatment of ureteral stone was 100%.

CONCLUSIONS

A holmium laser is a safe and effective modality of ureteroscopic lithotripsy in patients with significant renal impairment or even obstructive anuria. The use of holmium laser with ureteroscopy may be considered in this group of patients as long as the general condition of the patient permits the safe administration of anesthesia.

The management of penile fracture based on clinical and magnetic resonance imaging findings

OBJECTIVE

To present our experience with repairing penile fracture, based on clinical and magnetic resonance imaging (MRI) findings.

PATIENTS AND METHODS

Between December 2002 and October 2004, 14 men (19-64 years old) presented to our centre with a penile fracture. Two patients had urethral bleeding. MRI was used before surgery in all patients, and the repair comprised a localized longitudinal penile incision in 13 men. This incision was designed according to the tunical tear site and size already depicted by MRI. One case was managed conservatively, as MRI confirmed an intercavernosal haematoma with no tunical tear. The follow-up was 4-21 months.

RESULTS

The tear involved one corpus cavernosum in 11 patients; two were associated with urethral injury. The course after repair was uneventful in all men; the follow-up showed no erectile dysfunction in any. The patients reported neither pain nor penile curvature during erection.

CONCLUSION

MRI is a simple and informative investigation for evaluating and documenting a penile fracture, and it improves the management plan.

Nephrotoxicity of low-dose methotrexate in guinea pigs: an ultrastructural study

The nephrotoxicity of low-dose methotrexate (MTX) and the rescue effect of leucovorin were studied by electron-microscopic examination of the kidney of guinea pigs. One group received MTX as a single weekly dose of 10 mg/kg, i.p.; a second group received a similar dose divided into three equal fractions. The third group received MTX rescued with an equal dose of leucovorin. The distal convoluted tubule showed cell swelling, fragmentation of the endoplasmic reticulum and loss of mitochondrial cristae and matrix. Leucovorin minimized these changes. The proximal tubule and the glomerulus were not affected. Low-dose MTX induced a nephrotoxicity in the distal convoluted tubule which could be minimized by leucovorin. Mild myelosuppression was also observed.

The poll glands of the dromedary (Camelus dromedarius): ultrastructural characteristics

The poll glands of the camel are tubuloalveolar glands. They consist of lobules separated by interlobular connective tissue. Adrenergic axons and blood vessels including fenestrated capillaries are present in the intralobular connective tissue in close proximity to the secretory cells. The prominent features of the secretory cell cytoplasm are many mitochondria, smooth endoplasmic reticulum, and many vesicles in various secretory stages. It is concluded that the secretory cells have apocrine as well as merocrine modes of secretion. The glands may have the ability to uptake hormones and concentrate them. Additional work is needed before considering these glands as steroid-secreting glands.

Cellular and humoral immunological changes in chronic renal failure associated with schistosomiasis

The changes that occur in cell mediated and humoral immunity in patients suffering from chronic renal failure associated with schistosomiasis were studied. There was a decrease in T3%, T4% and T4/T8 ratio. IgG, IgM and IgE levels were found to be increased in such cases. It was concluded that there was a reciprocal relationship between cell mediated immunity and IgE levels in cases with chronic renal failure associated with bilharzial hepatosplenomegaly.

Characterization of serum lysosomal enzymatic activities. III. Effect of infectious influenza in Egyptian equines

An outbreak of infectious influenza was recognized in Menofeia governorate in October 1989. Eight naturally influenza infected as well as 8 healthy control horses, mules and donkeys were selected for collection of blood and sera separation to estimate four lysosomal enzymatic activities and to describe the clinical findings, which were fever, congested nasal, conjunctival membranes and cough. Bronchopneumonia followed later with bilateral purulent nasal discharge as a complication in 2 donkeys. Thereafter laboured breathing occurred. Therefore a therapeutic penicillin-streptomycin dose was injected to safeguard against the secondary bacterial invasion. All lysosomal enzyme levels in serum of diseased equines were subjected to consistent regression except N-acetyl-beta-glucosaminidase -beta-NAG) that behaved very highly significant activity, probably due to the acid pH resulting from bronchopneumonia and respiratory acidosis which override the inhibitory action of the antibiotics. Influenza virus may inhibit the synthesis of the pulmonary surfactant in alveolar and bronchial epithelium, thereafter, the animals suffered from respiratory distress and bronchospasm with resultant decreased acid phosphatase (ACP) value which was histochemically located in both sites. The disappearance of alpha- and beta-galactosidases (alpha-GAL & beta-GAL) from the serum of diseased animals can be attributed to the antibiotic dose.

Characterization of serum lysosomal enzymatic activities. II. Effect of lumpy skin disease in Egyptian cows

Clinical findings and lysosomal enzymes (LYE) in eight lumpy skin diseases (LSD) cows and same number of healthy ones were reported in Tal-El Baker village and Tal Alkabir centre, Ismailia province, Egypt. LSD began with fever, anorexia, skin lesions in form of nodules all over the body, which disappeared spontaneously or gathered to form large lumps. It was complicated with respiratory manifestation, corneal opacity, mastitis, dehydration and later on recumbency. It is noteworthy that the level of 3 LYE showed the same trend of significant reduction in acute stage of the disease (5 days after occurrence of LSD) probably due to injection of animals with a therapeutics dose of terramycin. Acid-phosphatase (ACP) enzyme is the sole that behaved very high significant increase in the serum in acute stage of LSD due to the damaged tissues caused by the virus. It underwent insignificant decrease in late stage of the disease (20 days after its occurrence) to restore the normal LYE level in control cows indicating recovery. Alpha-galactosidase (alpha-GAL) decreased perpetually by the progression of LSD because of the decreased bactericidal index which ist in concomitance with the secondary bacterial invader. N-acetyl-beta-glucosaminidase (beta-NAG) and beta-galactosidase (beta-GAL) in LYE had the same fluctuating manner. The activities showed very highly significant decrease in acute stage, followed by highly significant and significant increases (late LSD stage) respectively. The appreciable significant increase of beta-GAL may declare the effect of anorexia on LSD. In view of these findings, it can be postulated that LSD may be diagnosed and prognosed through LYE changes in the serum.

Characterization of serum lysosomal enzymatic activities. I. Effect of dietary urea in dairy cows

The experiment was carried out on ten Holstein dairy cattle fed on conventional concentrate as base diet for 15 days, then turned on unconventional concentrate diet supplemented with 3% urea (CM-U) for 45 days to study the effect of four lysosomal enzymes in both states. The N-acetyl-beta-glucosaminidase enzyme level reflected the highest value among other enzymes inspite of its significant drop in the serum after feeding cows on the unconventional ureated diet. Beta-galactosidase was the sole enzyme to rise significantly in the serum of cows during the unconventional ureated diet feeding. Acid phosphatase and alpha-galactosidase showed highly significant decreases due to the effect of the tested diet.

Light and electron microscopic observations on the cerebellum of guinea pigs following low-dose methotrexate

The neurotoxicity of single and divided low-dose methotrexate (MTX) and the rescue effect of leucovorin (folic acid) were investigated by light and electron microscopic examination of the cerebellum of Guinea pigs. One group of animals received a single weekly intraperitoneal MTX in a dose of 10 mg/kg, a second received a similar dose divided into three equal fractions, and the third group received MTX rescued with an equal dose of leucovorin. The results showed degeneration of Purkinje cells indicated by shrinkage and distortion of perikarya, dissolution of mitochondrial cristae, and nuclear and nucleolar changes in all groups which received MTX. There was also astrocytic proliferation and perivascular edema. Lesser changes were found in the group which was rescued with leucovorin. The degenerative changes in the cerebellum particularly those of the Purkinje cells explain the neurological signs reported in cancer patients treated with MTX.

Studies on gangrenous mastitis in goats

One hundred and fifty goats were diagnosed as having proven gangrenous mastitis. The disease was categorized into early, intermediate and late stages. Gangrenous mastitis in goats is typified by a sudden onset, dark hyperemia, and edema with progressive discoloration of the distal part of the udder. The disease affected lactating goats but not the dry ones. Coagulase positive Staphylococcus aureus was isolated from 60% of composite and half milk samples obtained from the diseased goats. The histopathological changes mainly comprised proliferation of connective tissue, thrombosis and necrosis involving a group of lobules. Treatment of the early and intermediate stages of the disease was successful through the administration of systemic and intramammary terramycin together with diuretics and topical antiseptic cream. The late stage of the disease was successfully treated only through surgery.

Ultrastructural morphometric observations on the extramural aortico-pulmonary bodies of the domestic fowl

The extramural aortico-pulmonary bodies of the domestic fowl were analysed in electron micrographs by point-counting morphometry. The Type I cell constituted about 34% of the total volume of the parenchyma, whereas the supporting cells (Type II cells, pericytes and Schwann cells) constituted about 26%. The blood capillaries occupied the lowest volume density of about 5%. The mitochondria and the dense-cored vesicles occupied about the same volume (8%) of the Type I cell cytoplasm. The results obtained in the present study are compared with other similar studies on the aortic and carotid bodies of mammals.

Morphometrics of the avian lung. 1. The domestic fowl (Gallus gallus variant domesticus)

The lungs of 5 domestic fowls have been analysed electron microscopically by standard morphometric methods. The anatomical diffusing capacity has been calculated from the relevant parameters. The blood-gas barrier consisted essentially of endothelium, basal lamina, and a very thin squamous epithelial cell. Granular cells are absent and interstitial tissue is minimal. The following measurements are mean values applying to both lungs together, in the fixed state: lung volume, 25.0 cm3; total intrapulmonary blood volume, 6.9 cm3; volume of the exchange tissue, 11.6 cm3; pulmonary capillary blood volume, 3.51 cm3; pulmonary capillary haematocrit, 62.7%; total intrapulmonary air volume, 16.61 cm3; air capillary volume, 6.68 cm3; surface area of the blood-gas barrier, 2.08 m2; surface area of the barrier per unit volume of exchange tissue, 179.5 mm2/mm3; arithmetic mean thickness of the tissue barrier, 1.20 micrometers; harmonic mean thickness of the tissue barrier, 0.314 micrometers; harmonic mean thickness of the plasma layer, 0.342 micrometers. The values of the maximum and minimum morphometric diffusing capacities for the lung (DL02 m) were respectively 3.55 and 1.50 ml O2/min/mm Hg; those for the membrane (Dmo2 m) were 13.61 and 12.01 ml O2/min/mm Hg.

Light microscopic morphometry of the lung of 19 avian species

The lungs of 107 birds of 19 different species from seven orders were fixed in situ. The mean volumes of both fixed lungs together ranged from 0.15 to 95.31 cm3. Histological sections of one lung from each bird were analyzed by point counting with a Zeiss integrating eyepiece to determine the volume densities and thence the absolute volumes of the main functional components of the lung. The mean volume density of the exchange tissue was highest in the 11 passeriform species (53.5%) and lowest in the 2 charadriiform species (34.6%); that for all of the 8 non-passeriform species was 42.6%. The possible significance of these variations in relation to the differing oxygen requirements of these groups of birds is discussed. The parabronchi showed minor variations in the degree of development of the interparabronchial septa, atria, interatrial septa, and atrial muscles. The diameter of the parabronchi (including the mantle of exchange tissue) ranged from about 0.34 mm in the passeriform species to about 0.63 mm in Anser anser; the lumen of the parabronchus accounted for about half of this diameter. Body weight an lung volume were strongly correlated (0.995); the allometric function relating lung volume to body weight was 29.5 w0.988.

Morphometric observations on the kidney of the camel, Camelus dromedarius

Morphometric analysis of the kidney of the camel was carried out on gross slices and histological sections using standard morphometric methods. The renal cortex occupied about 50% by volume of the kidney, and the ratio of the thickness of the medulla to that of the cortex was about 4:1. The relative thickness of the medulla was about 7.89. This parameter is an indicator of the lengths of the loops of Henle and vasa recta, and, according to the countercurrent theory, is consequently an indicator of the ability of the kidney to concentrate urine. In each kidney the volume and surface area of the cortical tubules and the number of glomeruli were determined and compared with these parameters in some other mammals. In addition the architectures of the renal pelvis and medulla and their significance in relation to the excretion of hypertonic urine were discussed. It was concluded that the kidney of the camel possesses the anatomical requisites for the production of hypertonic urine.

The avian bronchial arteries: species variations

The bronchial arteries arose from the oesophagotracheobronchial branches of the common carotid arteries. In the goose, duck, Muscovy duck, and turkey several small bronchial arteries supplied the whole length of each primary bronchus, including the orifices of the secondary bronchi. In the guinea-fowl and quail similar bronchial arteries supplied only the extrapulmonary part of the primary bronchus. In the pigeon a single true bronchial artery supplied the extrapulmonary part of each primary bronchus; this pair of bronchial arteries arose asymmetrically from a common bronchial trunk derived from the left oesophagotracheobronchial artery only. In this species, and in the guinea-fowl and quail, the intrapulmonary part of the primary bronchus was supplied by the pulmonary artery. There were no branches to the exchange tissue in any species. In all species the bronchial veins of the extra-pulmonary part of the primary bronchus drained via oesophageal veins, whereas those of the intrapulmonary part emptied into branches of the pulmonary vein.

Pulmonary arteriovenous anastomoses in the avian lung: do they exist?

A search for pulmonary arteriovenous anastomoses was made in 15 adult domestic fowls using Lycopodium spores and microspheres. The diameter of the spores and microspheres ranged from about 10 to 33 mum. To dilate any pulmonary arteriovenous anastomoses, the birds were warmed to induce panting, killed with chloroform, or injected intravenously with papavarine. The spores or microspheres were injected either into the jugular vein under anaesthesia, or into the pulmonary artery after death. After the pulmonary arterial injections, the effluent from the pulmonary vein, and histological sections of the lungs, were examined for spores or microspheres. When injections were made into the jugular vein, blood smears from the pulmonary veins, left atrium, and the aorta, as well as histological sections of the lungs and other organs were inspected. The results of all these experiments showed that no spores or microspheres were ever found on the venous side of the pulmonary circulation, indicating absence of pulmonary arteriovenous anastomoses.

The functional anatomy of the bronchial circulation of the domestic fowl

The bronchial circulation was studied in 25 adult domestic fowls. The right and left bronchial arteries originated caudal to the syrinx from a bronchoesophageal artery which is a branch of the right common carotid artery. Each bronchial artery ramified on the wall of the extrapulmonary part of the corresponding primary bronchus and finally anastomosed directly with a branch of the pulmonary artery at the hilus of the lung. Thr bronchial artery did not accompany the intrapulmonary part of the primary bronchus. The branches of each bronchial artery formed an anastomosing network on the wall of the extrapulmonary part of the primary bronchus. The calibre of the bronchial artery at its anastomosis with the branch of the pulmonary artery was greater than at its origin from the bronchoesophageal artery. Intravenous injections of Lycopodium spores indicated that the blood flows from the pulmonary artery into the bronchial artery. Small bronchial veins drained the extrapulmonary part of the primary bronchus into the pulmonary vein and the oesophageal veins. The intrapulmonary part of the primary bronchus was supplied by branches of the pulmonary artery and drained by tributaries of the pulmonary vein. The blood supply to the primary bronchus could constitute a shunt capable of passing blood from the pulmonary artery into the pulmonary vein without going through the exchange tissue. The parabronchial (atrial) muscles received a blood supply directly from the exchange tissue via septal venules which formed a network underneath the muscle bundles, without actually penetrating between the muscle cells. These venules drained into atrial veins which were tributaries of the pulmonary vein. The atrial muscles probably also received oxygen by direct diffusion from the parabronchial lumen. The pleura was supplied by the oesophageal branches of the bronchoesophageal artery, and by small twigs from the internal thoracic and intercostal arteries.

The functional anatomy of the pulmonary circulation of the domestic fowl

The architecture of the pulmonary circulation in the domestic fowl was studied in 30 birds of different breeds by injection techniques and serial sections. The branches of the cranial, caudomedial and caudolateral rami of the pulmonary artery form interparabronchial arteries which are essentially transverse to the long axis of the parabronchi. At the periphery of the parabronchus they give rise to intraparabronchial arterioles which form capillaries in the exchange tissue. Most of the capillaries drain into atrial veins via intraparabronchial venules. The atrial veins lie near the parabronchial lumen below the interatrial septa. Some of the capillaries empty into septal venules which form a network underneath the atrial muscles and empty into the atrial veins. The atrial veins draining any particular region converge into a single intraparabronchial vein which penetrates the exchange tissue radially to join an interparabronchial vein. The interparabronchial veins contribute to the cranial and caudal radices of the pulmonary vein. The anatomical pathways of blood and gas indicate a cross-current relationship between pulmonary arterial blood and bulk parabronchial gas flow, and a counter-current relationship between capillary blood and gas in the air capillaries.