1. Histology Histopathology, the microscopic study of diseased tissue, is an important tool in anatomical pathology, since accurate diagnosis of many diseases usually requires histopathological examination of samples.

2. Histology Processing Samples fix in 10% NBF. –48hrs -72 hrs -days

3. Paraffin infiltration and embedding into blocks. Cuts thin sections on slides (3-5um thick).

4. Deparaffinization and Rehydration

5. Stain tissue sections Hematoxylin and eosin stain (H & E stain) – structures staining blue are called basophilic because of their affinity for the basic dye (hematoxylin) – structures staining pink are called acidophilic because of their affinity for the acid dye (eosin),

6. Liver Hepatocytes – functional liver cells Hepatic Sinusoids – small blood vessel within liver tissue Hepatic Portal Vein – brings blood into the liver Central Vein – takes blood out of the liver Bile Duct – storage and drainage of bile Arteriole – delivers blood from artery to capillaries Glycogen Vacuole – used for glycogen storage

7. Hepatic sinusoid Hepatocyte Glycogen vacuole Liver 1000X

8. Erythrocytes visible within the central vein Hepatic sinusoids Liver 400x

9. 400X Liver Arteriole

10. RBC Arteriole Central vein Liver

11. Bile Duct

12. Liver Bile Duct

13. Liver White Blood Cells

14. Head Kidney Interrenal gland – Is a cortisol producing tissue.. Chromaffin cell – neuroendocrine cells that catalyze and secrete epinephrine, norepinephrine, and other hormones Postcardinal vein – Blood transport Hematopoietic tissue – where new blood cells are formed

15. A B 400x C A.Interrenal Gland B.Chromaffin Cell C.Postcardinal vein Head Kidney

16. Chromaffin cells Cardinal Vein Interrenal cells

17. Trunk Kidney Nephron – a renal tubule that removes waste and helps maintain homeostasis Renal corpuscle –Glomerulus – Pressure filters blood plasma into Bowman’s capsule –Basement membrane – glomerulus membrane that does the blood filtering –Bowman’s capsule – collects filtered blood plasma and connects with proximal tubule Proximal tubule – selectively transports nutrients (amino acids, glucose, salt, ect.) back into the blood Distal tubule – tubular secretion of molecules to balance pH Melanocytes – pigment cells Collecting duct and/or Mesonephric duct – collects urea from multiple nephrons and controls futher water reabsorption Connective tissue – fibres surrounding ducts

18. Proximal tubules Distal tubules Trunk Kidney Renal corpuscle

19. Glomerulus Basement membrane Bowmans capsule Trunk Kidney

20. A B A.Mesonephric Duct B.Melanocytes C.Connective tissue 400x C Trunk Kidney

21. Gills Filament – threadlike structure forming respiratory surface Lamella – fingerlike projections of the filament Goblet (or mucous) cell – secret mucus Chloride cell – acid/base regulation by Cl - and HCO 3 - excretion –Cells surface area becomes enhanced during alkalosis and decreases during acidosis Pillar (or pilaster) cell – lend support for lamelle Gill filament cartilage – center of filament for structural support

22. Gill filaments and lamellae Lamella A.Filament cartilage B.Pillar cell C.Chloride cell 40x A B C Gill

23. Goblet cells Epithelial cells Gill

24. Pillar cells Erythrocytes Chloride cell Gill

25. Laboratory Steps Use proper microscope handling procedures (distributed in Lab 2) Examine histology slides of liver, kidney, and gills Examine additional histology slides of other organs