Abdominal CT scans of 103 patients without evidence of renal disease were examined. Unsuspected simple renal cysts were demonstrated in 25 (24%). No cysts were demonstrated in patients less than 40 years old. Thereafter the number of cysts and the number of patients with cysts tended to increase with age. Cyst dimensions also increased. These observations suggest that the development of simple cysts of the kidney is related to aging.

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Glomerular size, shape and number were examined in 44 human kidneys obtained at necropsy. Intrarenal vascular appearances were assessed histologically and by post-mortem angiography. The mean cross-sectional area of glomeruli varied nearly three-fold and glomerular number varied more than three-fold when kidneys from different adult subjects were compared but kidneys from the same subject resembled one another in glomerular size and number. A significant negative correlation existed in the adult between glomerular number and dimensions. Glomerular numbers in the few immature kidneys studied were similar to those in adult kidneys but glomeruli were smaller. Glomerular numbers tended to decline as age and severity of age-related vascular changes increased but correlation was poor. The possibility remains that glomerular involution in the senescent kidney occurs independently of events in the vessels. In men, but not in women, totally hyalinised glomeruli were observed more frequently with increasing age but their presence did not appear to be related to the degree of vascular change. In the senescent kidney, glomerular lobulations tended to disappear. This, together with glomerular loss, must result in a reduction in the area available for filtration. Assessments of total glomerular surface area should take account of glomerular shape and dimensions as well as numbers.

A spectrum of rare urachal abnormalities in the adult is described, including urachal cyst, infected urachal cyst and abscess, and urachal carcinoma. The clinical and radiographic features are presented, and diagnosis using ultrasound, computed tomography, and needle aspiration is discussed. Treatment of infected urachal cysts with percutaneous catheter drainage is described.

1. The effects of a low calcium diet and of oophorectomy, separately and together, on cortical and trabecular bone mass, have been examined in mature female rats. 2. Calcium deprivation caused a significant decrease of weight, cortical cross-sectional area and ratio of cortical to total area in the femur, it significantly reduced the volume of trabecular bone and increased the percentage of osteoid surface in the tail vertebrae, and in addition increased the urinary excretion of phosphate and, initially, of hydroxyproline. 3. Oophorectomy caused similar though smaller changes in trabecular bone and urine, whereas the effects of oophorectomy on cortical bone were greater on a low calcium intake than on a normal intake. 4. The ash weight of the femora, expressed as a percentage of the total dry weight, was unaffected by calcium deprivation or oophorectomy alone but was significantly reduced when the two occurred together. 5. The percentage of resorption surfaces in the vertebrae tended to increase on the low calcium diet and after oophorectomy on the normal diet but decreased after oophorectomy on a low calcium diet. 6. It is concluded that oophorectomy and calcium deficiency each reduce bone mass in the adult rat but the greatest effect is seen when they are combined.