Clinical note: The inflammatory condition known as glomerulonephritis results from an autoimmune cross reaction on the part of the host against streptococcal antigens. Infections triggering this reaction can occur in either the skin or throat. The inflammatory response is largely confined to the glomeruli, damaging the capillaries and basal laminae to the extent that proteins and erythrocytes may appear in the urine. The injury results from antigen-antibody complexes getting stuck in the glomerular filter.

On the same slides (slides 14 and 144) examine the packed nephron components, cut mainly transversely and obliquely, and identify proximal convoluted tubules, the thin limbs and thick ascending limbs of the loops of Henle, distal convoluted tubules, and collecting tubules and ducts (Figs. 19-8, 19-9, and 19-11). In the cortex and medulla, identify peritubular capillaries and vasa recta respectively. Note the ultrastructural differences between proximal tubules (Fig. 19-8a) and distal tubules (Fig. 19-8b).

Name the epithelial type and major function of each of the following:

• PCT:
• Loop of Henle, thin limb:
• Loop of Henle, thick limb:
• DCT:
• Collecting tubule:

How do the histological features at different levels of the nephron correlate the major cellular activities or functions at these regions?

On slide 14 Examine glomeruli and locate one showing the juxtaglomerular apparatus (Fig. 19-12).

• Identify the macula densa in the distal convoluted tubule.
• Try to identify the specialized smooth muscle juxtaglomerular cells and the lacis cells (Fig. 19-12), although these will be difficult to find in most glomeruli.

What does the juxtaglomerular apparatus do and how does it do it?

Now for the ureter and urinary bladder.