Biology 11–12 · Year 12

Lamb kidney dissection: cortex, medulla, pelvis and ureter

Module 8: Non-infectious Disease and Disorders (Technologies and Disorders: loss of kidney function)

PracticalMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

The idea

The kidney's outer cortex, inner medulla and central pelvis are the visible regions of the kidney's filtering units (nephrons), and seeing them explains what dialysis must replace when kidney function is lost.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

Sharp instruments
Bacteria on raw offal
Distress at dissection

Controls

Cut away from the body; carry scalpels on a tray; eye protection
Gloves; disinfect surfaces; wash hands thoroughly; never store tissue in a food refrigerator
Offer an alternative task to anyone who opts out

Note

The kidneys are bought from a butcher or an abattoir; disinfectant per RiskAssess (https://www.riskassess.com.au/). NSW permits the dissection of animal parts bought from a butcher, supermarket or abattoir, no learner can be compelled to dissect, and any other source needs Schools Animal Care and Ethics Committee approval (https://education.nsw.gov.au/teaching-and-learning/animals-in-schools/animals-in-schools-issues/dissection-of-animals); the Department's Animals in Schools framework sets out the school's wider obligations (https://education.nsw.gov.au/teaching-and-learning/animals-in-schools). Be aware that a learner may know someone on dialysis, as the Department's Module 8 guide notes.

What you need

Lamb or sheep kidneys from a butcher, one per pair, with the ureter and vessels attached where possible
Dissection board; scalpel; scissors; forceps; blunt probe; ruler; hand lens
Gloves; eye protection; disinfectant; waste bag

How to do it

Remove any fat and the thin outer capsule; record the kidney's shape, colour, mass and length.
Find the hilum and identify the renal artery (thicker wall), renal vein (thinner wall) and ureter.
Cut the kidney lengthways through the hilum into two equal halves.
Identify the thin capsule, the outer cortex, the inner medulla and the fused, crest-like papilla (the renal crest) where the medulla projects into the pelvis, which leads into the ureter; the sheep carries one renal crest rather than the separate papillae and calyces of a human or bovine kidney, so look for a single ridge; measure the cortex thickness in three places.
Examine a thin slice of cortex under the hand lens for the tiny red dots of glomeruli.
Draw and label the cut face, then annotate where filtration, reabsorption and urine collection occur and which of these a dialysis machine replaces.

What you should see

The cut face shows the thin membranous capsule, an outer cortex, and an inner medulla that ends in a fused, crest-like papilla projecting into the pelvis, which may be filled with white fat, as the Valdosta State University dissection protocol describes; the sheep, like the dog and the horse, has a fused, crest-like papilla (the renal medullary crest) rather than the multiple papillae of a pig, an ox or a human, so the separate calyces of a human kidney are not there to find; the pelvis narrows into the ureter, and the renal artery has a thicker wall than the vein. The learner knows it worked when cortex, medulla, renal crest, pelvis and the three structures at the hilum are identified and the cortex thickness has been measured.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

The kidney is a sieve that lets only waste through; it filters almost everything small and then reabsorbs what the body needs.
Urine is stored in the kidney; the pelvis collects it and the ureter carries it to the bladder.
The cortex and medulla do the same job; the glomeruli that filter blood lie in the cortex, while the loops and collecting ducts that concentrate urine run through the medulla.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-15 BIO11/12-7
Biology 11–12 Syllabus (2025), Year 11 focus area Cells to systems; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-11-02
Biology 11–12 Syllabus (2025), Year 11 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-11WS-03 BI-11WS-07
Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.

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