Ureteral structure and ultrastructure. Part I. The normal human ureter

Ureteral structure and ultrastructure. Part V. The dysplastic ureter

The ureters in neonates and infants can be anatomically and functionally so severely compromised to warrant the term "dysplasia". The clinicopathologic criteria for this diagnosis are: 1) a variable degree of dilatation on the excretory urogram and/or cystogram. 2) poor or absent ureteral motility as observed on cine-fluoroscopy or at operation, 3) poor muscularization and decreased muscle/connective tissue ratio under light microscopy and 4) small and deformed muscle cells with nexuses that are markedly decreased or absent and intracellular organelles that are poorly defined under electron microscopy. Excessive collagen and ground substance are present throughout the ureter. Although these qualitative and quantitative structural abnormalities are non-specific and can occur as a result of prenatal obstruction and postnatal infection, their severity in early postnatal life and their frequent association with dysplastic kidneys suggest congenital dysplasia as their etiology.

Idiopathic hydronephrosis--the diuresis renogram: a new non-invasive method of assessing equivocal pelvioureteral junction obstruction

A new method to evaluate patients with equivocal obstruction of the pelvioureteral junction is described. It involves the performance of a standard 131iodine-hippuran renogram followed by a second renogram 3 minutes after an intravenous injection of the diuretic, frusemide. When the 2 results are inspected together it is found that the patients can be separated into 4 groups: 1) normal, 2) obstructed, 3) atonic and 4) partially obstructed. The results in 23 children and 27 adults with suspected obstruction of the pelvioureteral junction are presented. Obstruction was confirmed in 18 patients and excluded in 32. The correlation between the renogram results and clinical, radiological and operative findings is discussed. The technique is simple, accurate and non-invasive, and it is recommended after excretory urography before proceeding to more invasive tests.

Ureteral structure and ultrastructure. Part III. The congenitally dilated ureter (megaureter)

A selected group of congenitally dilated ureters was examined under light and electron microscopy, and the findings were compared to the clinicoradiologic features of each ureter. These dilated ureters exhibit qualitative and/or quantitative muscular deficiencies. The obstructed megaureters secondary to posterior urethral valves and the megaureters with reflux show non-specific pathologic changes in response to increased work load or decompensation but infection within the ureter is detrimental to the muscle cells. The ureters in babies with prune belly syndrome suffer from reduced muscle cell population and a distinct myopathy involving the myofilaments within the muscle cells. The dysplastic ureter is morphologically and end stage ureter wherein the muscle cells are severely compromised. Whether this is an underdevelopment or exhaustion from repeated infections is a matter for speculation.

Ureteral structure and ultrastructure. Part IV. The dilated ureter, clinicopathological correlation

The potential of electron microscopy in the study of ureteral dilatation is seldom exploited but ureteral biopsies from 29 congenitally dilated ureters were examined under light and electron microscopy. A correlation between the pathological findings and the result of the surgical correction of these ureters is shown. The prospects of ureteral functional recovery can be predicted when the muscle cell integrity is considered.

Ureteral structure and ultrastructure. Part II. Congenital ureteropelvic junction obstruction and primary obstructive megaureter

The structure and ultrastructure were studied of 48 specimens from cases of congenital ureteroplevic junction obstructions and primary obstructive megaureters. Under light microscopy a spectrum of findings occurs, extending from the nearly normal to the clearly abnormal obstructive segments. However, under electron microscopy there were consistent abnormalities: 1) excessive collagen fibers between and around the muscle cells and 2) a group of compromised muscle cells proximal to the collagenous segment. These findings are responsible for functional discontinuity via the nexus and indistensibility of the pathologic areas. The high resolution of the electron microscope allows clearer definition of these obstructions and the impact of these findings on surgical remodeling is discussed.