Answers

What subcellular organelle is responsible for attracting the basic stain? Rough endoplasmic reticulum.

#115 Gall bladder, H&E

Why are the microvilli not visible on all cells lining the lumen? Depending on the orientation of the section, certain cellular components may not be visible in all cells.

QUESTIONS

1. What are serial sections and why are they important? A continuous series of sections, which reveal structures in three dimensions. Serial sections are important for visualizing the three dimensional structure of the tissue in order to differentiate artifact from pathology.

2. What is the relationship between heterochromatin and the synthetic activity of DNA? Heterochromatin is transcriptionally inactive DNA. A euchromatic nucleus is relatively unstained because the genetic material is being read.

3. Where is the site of synthesis of ribosomal RNA? The nucleolus.

4. What is the function of mitochondrial cristae? Site of enzymes related to ATP production.

5. What is the functional significance of the Golgi complex? Site of posttranslational modifications, packaging, and sorting of proteins.

6. How many membranes comprise the nuclear envelope? Two. The wall of a mitochondrion? Two.

7. What are the cytological and functional differences between cilia and microvilli? Cilia are motile microtubule based structures; microvilli are non-motile actin based structures.

8. Know the structural characteristics and functional significance of the following organelles and inclusions: nucleus, nucleolus, ribosomes, endoplasmic reticulum (two types), mitochondria, Golgi apparatus, lysosomes, microtubules, cilia, microvilli, glycogen, lipid, peroxisomes. Which of these require more than pure light microscopy for their identification? What additional techniques can be used?