Light Microscopic features of Organelle or Inclusion

Question 1

Largest organelle within the cell with distinct
boundary

Often visible nucleoli and chromatin pattern regions

Answer 1

Nucleus

Question 1

Roughly circular, basophilic region within the nucleus

Visible in living cells throughout interphase with
interference microscopy

Answer 1

Nucleolus

Question 2

Not visible in Light microscope

Answer 2

Plasma membrane
Ribosomes
Proteasomes
Endosomes

Question 3

Often observed as basophilic region of cytoplasm referred to as ergastoplasm

Answer 3

rER

Question 4

Not visible
Cytoplasm in region of sER may exhibit distinct
eosinophilia

Answer 4

sER

Question 5

Sometimes observed as “negative staining” region

Appears as network in heavy metal–stained
preparations

Visible in living cells with interference microscopy

Answer 5

Golgi apparatus

Question 6

Observed only when vesicles are very large
(e.g., zymogen granules in pancreas)

Answer 6

Secretory
vesicles

Question 7

Sometimes observed in favorable situations (e.g., liver or nerve cells) as miniscule, dark dots; visible in living cells stained with vital dyes (e.g., Janus green)

Answer 7

Mitochondria

Question 8

Observed as a “purple haze” region of cytoplasm metachromasia with toluidine blue–stained specimen

Answer 8

Glycogen

Question 9

Visible only after special enzyme histochemical staining

Answer 9

Lysosomes and Peroxisomes

Question 10

Only observed when organized into large structures (e.g., muscle fibrils)

Answer 10

Cytoskeletal elements

Question 11

Readily visible when extremely large (e.g., in
adipocytes)

Appear as large empty holes in section (lipid itself is usually removed by embedding solvents)

Answer 11

Lipid droplets