A tortuous proximal urethra in urorectal septum malformation sequence?

We observed a newborn boy with urorectal septum malformation sequence. Anomalies of the genitalia and rectum were present. He expired on the first day of life, due to severe lung hypoplasia. Autopsy showed a colon that ended in a blind sac, an enlarged bladder with no grossly visible urethra, and dysplastic kidneys. A cone-shaped tissue at the usual site of the bladder outlet contained tortuous and slit-like lumina, suggesting an undeveloped proximal urethra. The urethral structure was lined by transitional epithelium with squamous metaplasia. Many small buds-lined with columnar epithelium-branched from the urethral structure. These ductal buds lined with columnar epithelium stained for prostatic acid phosphatase. Basal cells surrounding the ductal buds stained for p63 and high molecular weight cytokeratin-supporting an interpretation that the buds were early prostatic ducts with normal histology. To our knowledge, these are the first histological images of an undeveloped, obstructed urethra associated with the urorectal septum malformation sequence.

Ureteral tumor thrombus from renal cell carcinoma extending into bladder.

Tumor thrombus from renal cell carcinoma (RCC) usually occurs within the renal vein. We present the first report of a tumor thrombus from RCC extending from the kidney down the ureter and into the lumen of the bladder. This case both: (1) provides evidence for growth of RCC along the urinary tract, and (2) poses a staging dilemma.

Feedback control of glomerular vascular tone in neuronal nitric oxide synthase knockout mice.

For further elucidation of the role of neuronal nitric oxide synthase (nNOS) in macula densa (MD) cells, experiments were performed in anesthetized nNOS knockout mice (nNOS -/-). At comparable levels of arterial BP, renal blood flow was not significantly different between nNOS +/+ and nNOS -/- (1.7 +/- 0.2 versus 1.4 +/- 0.1 ml/min), and autoregulation of renal blood flow was maintained to a pressure level of approximately 85 mmHg in both groups of mice (n = 6 in each group). The fall in proximal tubular stop-flow pressure in response to an increase in loop of Henle perfusion rate from 0 to 30 nl/min was comparable in nNOS +/+ and -/- mice (40.7 +/- 1.6 to 32 +/- 2 mmHg versus 40.6 +/- 1.6 to 31.6 +/- 2 mmHg; not significant; n = 13 versus 18 nephrons). Luminal application of the nonselective NOS inhibitor nitro-L-arginine (10(-3) and 10(-2) M) enhanced the perfusion-dependent fall in stop-flow pressure in nNOS +/+ (7 +/- 1 to 13 +/- 2 mmHg; P < 0.05) but not in nNOS -/- (7 +/- 1 to 8 +/- 1 mmHg; not significant) mice. nNOS -/- mice exhibited a lower nephron filtration rate, compared with nNOS +/+, during free-flow collections from early distal tubules (influence of MD intact, 7 +/- 0.7 versus 10.9 +/- 1 nl/min; P = 0.002) but not from late proximal tubule (influence of MD minimized, 10.1 +/- 1 versus 11.7 +/- 1 nl/min; not significant; n = 16 nephrons). Distal Cl concentration and fractional absorption of fluid or chloride up to the early distal tubule was not different between nNOS -/- and +/+ mice. The data indicate that nNOS in MD tonically attenuates the GFR-lowering influence of ambient luminal NaCl, which may serve to increase the fluid and electrolyte load to the distal tubule, consistent with a role of MD nNOS in tubuloglomerular feedback resetting.