Page 103 - Atlas of Histology with Functional Correlations

Major microtubule-forming center and mitotic spindles

Centrioles perpendicular to one another; contain nine clusters of three
microtubules each arranged in a circle
Before mitosis, centrioles replicate
During mitosis, centrioles form mitotic spindles to control distribution of
chromosomes

Centrioles induce formation of basal bodies and microtubules in cilia and
flagella

CYTOPLASMIC INCLUSIONS

Temporary structures such as lipids, glycogen, crystals, and pigment

NUCLEUS AND NUCLEAR ENVELOPE

Nucleus contains chromatin, nucleoli, nuclear matrix, and cellular DNA

Double membrane called the nuclear envelope surrounds the nucleus
Nucleolus is not membrane bound
Outer membrane of nuclear envelope contains ribosomes and is continuous
with rough endoplasmic reticulum

Nuclear pores at intervals in the nuclear envelope
Nuclear pores control movements of material between nucleus and cytoplasm

SURFACES OF CELLS

Junctional Complex

Zonula occludens or tight junctions form an effective epithelial barrier

Transmembrane proteins claudin fuse the outer membranes of adjacent cells
to form tight junctions
In zonula adherens or adhering junctions, transmembrane proteins attach to

cytoskeleton and bind adjacent cells
Actin filaments attach zonula adherens
Desmosomes are spotlike structures, very prominent in skin and cardiac cells

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