The Carolina Mammal Kidney Dissection Guide is a general set of instructions for dissecting mammal kidneys. With each type of kidney, there will be differences in the size of the structures and kidney regions, but the general structures and their relative location will be the same or very similar.
Follow safe laboratory practices when performing any dissection. Wear safety glasses or goggles, gloves, and lab aprons when dissecting. Perform dissections on a dissecting tray or pan to contain specimens and fluids. Be careful when using sharp instruments, such as scalpels, forceps, teasing needles, and scissors.
1. Review the glossary provided at the end of this dissection guide. Refer to the diagram of the kidney as a general reference as you observe and identify external and internal structures. 2. Observe the renal capsule. This structure is made up of dense, irregular connective tissue and provides protection as well as helps maintain shape. Remove any adipose tissue that may be attached to the capsule. 3. Locate the hilus. This is an indentation where the ureter and blood vessels enter and exit the kidney. Remove excess adipose tissue to observe the ureter more closely. The renal artery and vein may be difficult to locate; they were severed close to the hilus when the kidney was removed from the animal. 4. Make a frontal section through the kidney. Locate the cortex and medulla. The medulla lies below the cortex. Observe and record the appearance of each region.
5. The medulla consists of numerous conical structures called renal pyramids. The base of each pyramid lies next to the cortex, while the tip forms a renal papilla. Each papilla projects into the renal sinus. Locate the renal pyramids, renal papilla, and renal sinus. 6. Renal pyramids are separated by bands of tissue called renal columns. Each column begins in the cortex and extends through the medulla. Examine the texture of this tissue. Columns have a granular texture similar to that of the cortex. Capsule Cortex Medulla Pyramid Papilla Column Hilus Renal artery Renal vein Major calyx Minor calyx Pyramid Arcuate artery Arcuate vein Interlobar artery Interlobar vein Ureter Pelvis Sinus
7. Each renal pyramid and adjacent cortical region make up a renal lobe. Urine production occurs in the renal lobes. Each renal papilla discharges urine into a cup-shaped minor calyx. Four or five minor calyces merge to form a major calyx. Major calyces merge to form the renal pelvis. Using a probe, trace the path of urine from the renal pyramids to the renal pelvis. ©2005 Carolina Biological Supply Company Printed in USA
8. Examine the renal pelvis. It is formed by a wall of thick fibrous tissue and forms the expanded end of the ureter. 9. Using a scalpel, carefully cut one wall of the ureter and extend the incision to the hilus. The ureter is continuous with the renal pelvis. Observe the fine ridges on the endothelial lining of the ureter and renal pelvis. 10. Once you have observed all the structures of the kidney, dispose of the specimen in accordance with local guidelines and your teacher’s instructions.
Calyx – cup-like division found in the renal medulla; minor calyces (plural) empty into major calyces. Hilus – depression where the renal artery, renal vein, and ureter enter and exit the kidney. Renal artery – branch from the abdominal aorta that supplies the kidney with oxygenated blood. Renal capsule – dense, irregular connective tissue layer that protects the kidney and helps maintain its shape. Renal corpuscle – glomerulus enclosed within a
glomerular capsule; site of filtration. Renal cortex – outer region of the kidney. Renal lobe – consists of a pyramid, portion of the cortex at the pyramid base, and a portion of the adjacent renal column. Renal medulla – inner portion of the kidney. Renal papilla – apex of a renal pyramid; continuous with the minor calyx. Renal pelvis – large cavity that receives urine from major calyces; continuous with ureter. Renal pyramid – cone-shaped structure found in the medulla with its base facing the cortex and the apex facing the hilus. Renal vein – blood vessel exiting the kidney carrying filtered, deoxygenated blood to the inferior vena cava. Ureter – tube that connects the kidney to the urinary bladder.
Carolina’s Perfect Solution®
Independent, certified laboratory analyses of specimens fixed in Carolina’s Perfect Solution® have found it to be nontoxic and free of dangerous off-gassing. This means that, for safety purposes, classrooms and labs using Carolina’s Perfect Solution specimens do not require specialized ventilation. Carolina does recommend using some active ventilation when working with any preserved specimens or chemicals. The safe nature of Carolina’s Perfect Solution also means that in most localities there are no mandated disposal requirements. Be sure to check with local sewer and landfill authorities, as local procedures may vary.
Carolina’s Perfect Solution® Specimens Available From Carolina Biological Supply Company Carolina’s Perfect Solution® Cow Eye Carolina’s Perfect Solution® Sheep Eye Carolina’s Perfect Solution® Sheep Brain Carolina’s Perfect Solution® Pig Heart Carolina’s Perfect Solution® Pig Kidney RN-22-8903 RN-22-8763 RN-22-8703 RN-22-8563 RN-22-8573
Carolina CarosafeTM Preservative
Carosafe™ is a holding solution for biological specimens. It contains no formaldehyde and is not a tissue fixative. Most specimens in Carosafe are first preserved with a formalin solution and then placed in formaldehyde-free Carosafe. This produces a formalin-preserved specimen that, when dissected, minimizes student and educator exposure to formaldehyde.
Preserved animals shipped in Caropaks have been processed with Carosafe and are as “odorless” as effective fixation and preservation techniques allow. They are packaged in vacuum-sealed, double-layered plastic barrier bags. Specimens may be packaged one specimen per pack or many per pack.
Sheep Kidney (Carosafe™) Sheep Kidney (Carosafe™) Sheep Kidney (Carosafe™) Pig Kidney (Caropak® Single) Pig Kidney (Caropak® Single) Pig Kidney (Caropak® Single) Plain Double Injected Triple Injected Plain Double Injected Triple Injected RN-22-8800 RN-22-8810 RN-22-8820 RN-22-8571 RN-22-8581 RN-22-8591
Because local regulations may vary from federal and state regulations, we recommend that you discuss disposal of preserved specimens with your institution’s or system’s environmental representative.