laburinary 03

Urinary System Lab Supplement: 

Urinary System Lab Supplement Medical Cell and Tissue Biology Dr. H. Wayne Lambert April 14th, 2003 (11:00AM) A Renal Corpuscle Medulla vs. Cortex

Urinary System: 

Urinary System The urinary system consists of the two kidneys and the excretory passages, which convey urine from the kidneys to the exterior of the body. Excretory passages include the minor calyces, major calyces, renal pelvis (one for each kidney), the two ureters, the urinary bladder, and the urethra. Wheater’s Fig.16.1 Wheater’s Fig.16.2

Parts of the Kidney: 

Parts of the Kidney Within the kidney, utilize the diagram on the right to identify the capsule, cortex, renal corpuscles, and medulla, which has no renal corpuscles. The slide on the left is a representative section from this part of the kidney. Wheater’s Fig.16.2

Parts of the Kidney: 

Parts of the Kidney On the left, locate an area in the cortex where tubules run parallel to one another and are cut longitudinally. This is a pars radiata or medullary ray. On either side is a pars convoluta, which contains renal corpuscles and coiled tubules. B93 Monkey Kidney H&E X20 Wheater’s Fig.16.2 Medullary Ray Pars Convoluta medulla cortex

Kidney: Cortex versus Medulla: 

Kidney: Cortex versus Medulla With the same image, note the medullary rays are composed of collecting tubules. On either side is a pars convoluta, which contains renal corpuscles and coiled tubules. Slide B93 Monkey Kidney H&E X20 Medullary Ray Pars Convoluta medulla cortex Pars Radiata Pars Convoluta Next, we will look at a higher magnification of this area of the pars convoluta.

Kidney: Convoluted Tubules: 

Kidney: Convoluted Tubules Within the pars convoluta, identify proximal convoluted tubules (PCT) and distal convoluted tubules (DCT). The PCT is more than twice as long as the DCT, so the majority of tubules are PCT. Slide B92 Human Kidney PAS X200 DISTINGUISHING CHARACTERISTICS PCT star-shaped lumen glycocalyx debris in lumen highly eosinophilic tall cuboidal cell DCT more cells per lumen clear lumen (no debris) no or minimal brush border less eosinophilic cells normal cuboidal epithelium

Kidney: PCT versus DCT: 

Kidney: PCT versus DCT The diameter of the distal convoluted tubules (DCT) is much smaller than the proximal convoluted tubules (PCT), although the luminal diameter of the two tubules are approximately the same. DISTINGUISHING CHARACTERISTICS PCT star-shaped lumen is due to the autolysis of the brush border. Fewer nuclei appear in cross-section and cell boundaries are indistinct. Basal infoldings due to mitochondria DCT no precipitate in lumen more nuclei with distinct cell boundaries paler cytoplasm Slide B90 Human Kidney H&E X400 renal corpuscle renal corpuscle

Kidney: Renal Corpuscle: 

Kidney: Renal Corpuscle Wheater’s Fig.16.7 Slide B92 Human Kidney PAS X200 Note the schematic of the renal corpuscle (glomerulus) on the right and how it is suspended in the urinary (Bowman’s) space. The afferent and efferent arterioles enter and leave the glomerulus at the vascular pole. DCT

Kidney: Vascular Pole: 

Kidney: Vascular Pole Wheater’s Fig.16.18b Slide B94 Rabbit Kidney PAS X200 Search for an area within the renal corpuscle where a distal convoluted tubule makes contact with the vascular pole of the renal corpuscle. Note the macula densa and juxtaglomerular cells

Kidney: Vascular Pole: 

Kidney: Vascular Pole Slide B94 Rabbit Kidney PAS X200 The macula densa of the distal convoluted tubule and the juxtaglomerular (JG) cells constitute a juxtaglomerular apparatus (JGA). The JG cells secrete renin and erythropoietin. PCT PCT

Kidney: Glomerulus Reminder: 

Kidney: Glomerulus Reminder Remember the proximal convoluted tubules (PCT) is associated with the urinary pole and the distal convoluted tubules (DCT) is associated with the vascular pole. Slide B92 Human Kidney PAS X200 PCT DCT vascular pole urinary pole NOTICE THE 2nd & 3rd letters: proximal tubule is at urinary pole distal tubule is at vascular pole Bowman’s Capsule (parietal layer)

Kidney: Collecting Tubules: 

Kidney: Collecting Tubules Photo of renal medulla with three collecting tubules (CT) consisting of cuboidal and some columnar cells. Slide B90 Human Kidney H&E X200 Collecting tubules, in contrast to the distal tubules, have very distinct cell boundaries. DCTs can be thin within the loop of Henle.

Kidney: Collecting Ducts: 

Kidney: Collecting Ducts Photo of renal papilla projecting into renal calyx. The apex of the papilla contains openings, the collecting ducts (of Bellini). These ducts deliver urine from the renal pyramid to the minor calyx. Slide B93 Monkey Kidney H&E X20 Collecting tubules, widen to form collecting ducts (columnar epithelium). The outer portion of the minor calyx is lined with transitional epithelium. renal papilla

Kidney: Renal Papilla: 

Kidney: Renal Papilla Higher magnification photo of renal papilla projecting into renal calyx. The openings seen within the papilla are the collecting ducts (of Bellini). Slide B93 Monkey Kidney H&E X100 Note the transitional epithelium lining the outer surface of the minor calyx. The renal papilla has a simple columnar epithelium renal papilla