Ebook Color atlas and text of histology (6th edition): Part 1

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Sixth Edition

Color Atlas and Text of

Histology

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Sixth Edition

Color Atlas and Text of

Histology
LESLIE P. GARTNER, PH.D.
Professor of Anatomy (Retired)
Department of Biomedical Sciences
Baltimore College of Dental Surgery

Dental School
University of Maryland
Baltimore, Maryland

JAMES L. HIATT, PH.D.
Professor Emeritus
Department of Biomedical Sciences
Baltimore College of Dental Surgery
Dental School
University of Maryland
Baltimore, Maryland

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Acquisitions Editor: Crystal Taylor
Product Manager: Catherine Noonan
Vendor Manager: Bridgett Dougherty
Art Director: Jennifer Clements
Marketing Manager: Joy Fisher-Williams
Designer: Joan Wendt
Compositor: SPi Global
Sixth Edition
Copyright © 2014, 2009, 2006, 2000, 1994, 1990 Lippincott Williams & Wilkins, a Wolters Kluwer business.
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Baltimore, MD 21201

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Philadelphia, PA 19103

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Library of Congress Cataloging-in-Publication Data
Gartner, Leslie P., 1943Color atlas and text of histology / Leslie P. Gartner, James Hiatt. — 6th ed.
p. ; cm.
Includes index.
Rev. ed. of: Color atlas of histology / Leslie P. Gartner, James L. Hiatt. 5th ed. c2009.

ISBN 978-1-4511-1343-3
I. Hiatt, James L., 1934- II. Gartner, Leslie P., 1943-. Color atlas and text of histology. III. Title.
[DNLM: 1. Histology—Atlases. QS 517]
611'.0180222—dc23
2012031983
DISCLAIMER
Care has been taken to confirm the accuracy of the information present and to describe generally accepted practices. However,
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9 8 7 6 5 4 3 2 1

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To my wife Roseann, my daughter Jen,
and my mother Mary
LPG

To my wife Nancy and my children
Drew, Beth, and Kurt
JLH

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Preface
We are very pleased to be able to present the sixth edition of our Color Atlas and Text of Histology, an atlas that
has been in continuous use since its first publication
as a black and white atlas in 1987. The success of that
atlas prompted us to revise it considerably, retake all of
the images in full color, change its name, and publish it
in 1990 under the title Color Atlas of Histology. In the
past 22 years, the Atlas has undergone many changes. We
added color paintings, published a corresponding set of
Kodachrome slides, and added histophysiology to the text.

The advent of high-resolution digital photography allowed
us to reshoot all of the photomicrographs for the fourth
edition, and we created a CD-ROM that accompanied
and was packaged with our Atlas. For the fifth edition, we
updated the Interactive Color Atlas of Histology and made
it available to the student on the Lippincott Williams &
Wilkins Website, , that could
be accessed from anywhere in the world via an Internet
connection. The online Atlas contained every photomicrograph and electron micrograph and accompanying legends present in the Atlas. The student had the capability
to study selected chapters or to look up a particular item
via a keyword search. Images could be viewed with or
without labels and/or legends, enlarged using the “zoom”
feature, and compared side-by-side to other images. Also,
the updated software allowed students to self-test on all
labels using the “hotspot” mode, facilitating learning and
preparation for practical examinations. For examination
purposes, the online Atlas contained over 300 additional
photomicrographs with more than 700 interactive fill-in
and true/false questions organized in a fashion to facilitate the student’s learning and preparation for practical
exams. Additionally, we have included approximately 100
USMLE Step I format multiple choice questions, based
on photomicrographs created specifically for the questions, which can be accessed in test or study mode.
We are grateful to the many faculty members throughout the world who have assigned our Atlas to their students whether in its original English or in its translated
form, which now counts 11 languages. We have received
many compliments and constructive suggestions not only

from faculty members but also from students, and we
tried to incorporate those ideas into each new edition.
One suggestion that we have resisted, however, was to
change the order of the chapters. There were several

faculty members who suggested a number of varied
sequences; they all made sense to us, and it would have
been very easy for us to adopt any one of the suggested
chapter orders. However, we feel partial to and very comfortable with the classical sequence that we adopted so
many years ago; it is just as valid and logical an arrangement as all the others that were suggested and, in the
final analysis, we felt that instructors can simply tell their
classes to use the chapters of the Atlas in a different
sequence without harming the coherence of the material.
Major changes have been introduced in this, the sixth
edition. The most exciting change is that we have completely rewritten and enhanced the textual material to
such an extent that it can be used not only as an Atlas
but also as an abbreviated textbook, which necessitated
the title change to indicate that major alteration; therefore,
the new title of the sixth edition is Color Atlas and Text
of Histology. Additionally, we have enlarged the trim size
of the book to its current size of 8½ × 11 inches, which
permitted us to enlarge the photomicrographs so that the
student can see details of the images to advantage. We
have created new tables for each chapter. We have also
included a new feature in the form of an Appendix that
describes and illustrates many of the common stains used
in the preparation of histological specimens. Probably the
second most exciting change that we have introduced into
this edition is the expansion of the Clinical Considerations
components, many of which are now illustrated with histopathological images that we were graciously permitted
to borrow from: Rubin, R., Strayer, D, et al., eds: Rubin’s
Pathology. Clinicopathologic Foundations of Medicine,
5th ed. Baltimore, Lippincott, Williams & Wilkins, 2008;
Mills, S.E. editor, Carter, D. Greenson, J.K. Reuter, V.E.
Stoler, M.H. eds. Sternberger’s Diagnostic Surgical Pathology,

5th ed., Philadelphia, Lippincott, Williams & Wilkins,
2010; and Mills, S.E., ed: Histology for Pathologists, 3rd ed.
Philadelphia, Lippincott, Williams & Wilkins, 2007.
vii

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viii

PREFACE

As in the previous editions, most of the photomicrographs of this book are of tissues stained with hematoxylin
and eosin. All indicated magnifications in light and electron micrographs are original magnifications. Many of the
sections were prepared from plastic-embedded specimens,
as noted. Most of the exquisite electron micrographs
included in this book were kindly provided by our colleagues throughout the world as identified in the legends.
As with all of our textbooks, the Color Atlas and Text
of Histology has been written with the student in mind;
thus the material is complete but not esoteric. We wish
to help the student learn and enjoy histology, not be

Gartner & Hiatt_FM.indd viii

overwhelmed by it. Furthermore, this book is designed
not only for use in the laboratory but also as preparation
for both didactic and practical examinations. Although
we have attempted to be accurate and complete, we

know that errors and omissions may have escaped our
attention. Therefore, we welcome criticisms, suggestions,
and comments that could help improve this book. Please
address them to

Leslie P. Gartner
James L. Hiatt

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Acknowledgments
We would like to thank Todd Smith for the rendering of the outstanding full-color plates and thumbnail
figures, Jerry Gadd for his paintings of blood cells, and
our many colleagues who provided us with electron
micrographs. We are especially thankful to Dr. Stephen
W. Carmichael of the Mayo Medical School for his
suggestions concerning the suprarenal medulla and Dr.
Cheng Hwee Ming of the University of Malaya Medical
School for his comments on the distal tubule of the

kidney. Additionally, we are grateful to our good friends
at Lippincott Williams & Wilkins, including our always
cheerful, and exceptionally helpful, Product Manager,
Catherine Noonan; Senior Acquisitions Editor, Crystal
Taylor; Art Director, Jennifer Clements; and Editorial
Assistant, Amanda Ingold. Finally, we wish to thank
our families again for encouraging us during the preparation of this work. Their support always makes the
labor an achievement.

ix

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Reviewers
Ritwik Baidya, MBBS, MS
Professor
Anatomy & Embryology
Saba University School of Medicine
Saba, Dutch Caribbeans
Roger J. Bick, MMedEd, MBS
Course Director for Histology
Associate Professor of Pathology
University of Texas Medical School at Houston
Houston, Texas
Marc J. Braunstein, MD, PhD
Internal Medicine Resident
Hofstra North Shore LIJ School of Medicine
Hempstead, New York

Sonia Lazreg
Medical Student

Mount Sinai School of Medicine
New York, New York
David J. Orlicky, PhD
Associate Professor
University of Colorado at Denver and Health
Sciences Center
Denver, Colorado
Guy Sovak, PEng, BSc, MSc, PhD
Assistant Professor
Coordinator Special Projects
Department of Anatomy
Canadian Memorial Chiropractic College
Toronto, Canada

Paul Johnson
Neurology Resident
University of Washington
Seattle, Washington

xi

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Contents
Preface
Acknowledgments
Reviewers

vii
ix
xi

CHAPTER 1 The Cell

2

GRAPHIC 1-1
1-2
1-3
1-4
PLATE 1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9

The Cell
The Organelles

Membranes and Membrane Trafficking
Protein Synthesis and Exocytosis

12
13
14
15

Typical Cell
Cell Organelles and Inclusions
Cell Surface Modifications
Mitosis, Light and Electron Microscopy
Typical Cell, Electron Microscopy
Nucleus and Cytoplasm, Electron Microscopy
Nucleus and Cytoplasm, Electron Microscopy
Golgi Apparatus, Electron Microscopy
Mitochondria, Electron Microscopy

16
18
20
22
24
26
28
30
32

CHAPTER 2 Epithelium and Glands
GRAPHIC 2-1

2-2
PLATE 2-1
2-2
2-3
2-4
2-5
2-6

Junctional Complex
Salivary Gland

42
43

Simple Epithelia and Pseudostratified Epithelium
Stratified Epithelia and Transitional Epithelium
Pseudostratified Ciliated Columnar Epithelium, Electron Microscopy
Epithelial Junctions, Electron Microscopy
Glands
Glands

44
46
48
50
52
54

CHAPTER 3 Connective Tissue
GRAPHIC 3-1

3-2
PLATE 3-1

34

58

Collagen
Connective Tissue Cells

66
67

Embryonic and Connective Tissue Proper I

68
xiii

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xiv

CONTENTS

3-2
3-3
3-4

3-5
3-6
3-7

Connective Tissue Proper II
Connective Tissue Proper III
Fibroblasts and Collagen, Electron Microscopy
Mast Cell, Electron Microscopy
Mast Cell Degranulation, Electron Microscopy
Developing Fat Cell, Electron Microscopy

CHAPTER 4 Cartilage and Bone
GRAPHIC 4-1
4-2
PLATE 4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9

Compact Bone
Endochondral Bone Formation
Embryonic and Hyaline Cartilages
Elastic and Fibrocartilages
Compact Bone
Compact Bone and Intramembranous Ossification

Endochondral Ossification
Endochondral Ossification
Hyaline Cartilage, Electron Microscopy
Osteoblasts, Electron Microscopy
Osteoclast, Electron Microscopy

CHAPTER 5 Blood and Hemopoiesis
PLATE 5-1
5-2
5-3
5-4
5-5
5-6

Circulating Blood
Circulating Blood (Drawing)
Blood and Hemopoiesis
Bone Marrow and Circulating Blood
Erythropoiesis
Granulocytopoiesis

CHAPTER 6 Muscle
GRAPHIC 6-1
6-2
PLATE 6-1
6-2
6-3
6-4
6-5
6-6

6-7
6-8
6-9

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80
88
89
90
92
94
96
98
100
102
103
104

108
116
118
119
120
122
123

126

Molecular Structure of Skeletal Muscle

Types of Muscle

132
133

Skeletal Muscle
Skeletal Muscle, Electron Microscopy
Myoneural Junction, Light and Electron Microscopy
Myoneural Junction, Scanning Electron Microscopy
Muscle Spindle, Light and Electron Microscopy
Smooth Muscle
Smooth Muscle, Electron Microscopy
Cardiac Muscle
Cardiac Muscle, Electron Microscopy

134
136
138
140
141
142
144
146
148

CHAPTER 7 Nervous Tissue
GRAPHIC 7-1
7-2

70

72
74
75
76
77

Spinal Nerve Morphology
Neurons and Myoneural Junctions

150
156
157

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CONTENTS

PLATE 7-1
7-2
7-3
7-4
7-5
7-6
7-7

Spinal Cord
Cerebellum, Synapse, Electron Microscopy
Cerebrum, Neuroglial Cells
Sympathetic Ganglia, Sensory Ganglia

Peripheral Nerve, Choroid Plexus
Peripheral Nerve, Electron Microscopy
Neuron Cell Body, Electron Microscopy

CHAPTER 8 Circulatory System
GRAPHIC 8-1
8-2
PLATE 8-1
8-2
8-3
8-4
8-5
8-6

GRAPHIC 9-1
9-2
9-3
9-4
9-5
PLATE 9-1
9-2
9-3
9-4
9-5
9-6

Elastic Artery
Muscular Artery, Vein
Arterioles, Venules, Capillaries, and Lymph Vessels
Heart

Capillary, Electron Microscopy
Freeze Etch, Fenestrated Capillary, Electron Microscopy

184
186
188
190
192
194

198

Lymphoid Tissues
Lymph Node, Thymus, and Spleen
B Memory and Plasma Cell Formation
Cytotoxic T-Cell Activation and Killing of
Virally Transformed Cell
Macrophage Activation by TH1 Cells

211
212

Lymphatic Infiltration, Lymphatic Nodule
Lymph Node
Lymph Node, Tonsils
Lymph Node, Electron Microscopy
Thymus
Spleen

214

216
218
220
222
224

GRAPHIC 10-1 Pituitary Gland and Its Hormones
10-2 Endocrine Glands
10-3 Sympathetic Innervation of the Viscera and
the Medulla of the Suprarenal Gland

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174
182
183

CHAPTER 10 Endocrine System

PLATE 10-1
10-2
10-3
10-4
10-5
10-6
10-7

158
160
162

164
166
168
170

Artery and Vein
Capillary Types

CHAPTER 9 Lymphoid Tissue

Pituitary Gland
Pituitary Gland
Thyroid Gland, Parathyroid Gland
Suprarenal Gland
Suprarenal Gland, Pineal Body
Pituitary Gland, Electron Microscopy
Pituitary Gland, Electron Microscopy

xv

208
209
210

228
237
238
239
240
242

244
246
248
250
251

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xvi

CONTENTS

CHAPTER 11 Integument
GRAPHIC 11-1 Skin and Its Derivatives
11-2 Hair, Sweat Glands, and Sebaceous Glands
PLATE 11-1
11-2
11-3
11-4
11-5

Thick Skin
Thin Skin
Hair Follicles and Associated Structures, Sweat Glands
Nail, Pacinian and Meissner’s Corpuscles
Sweat Gland, Electron Microscopy

CHAPTER 12 Respiratory System
GRAPHIC 12-1 Conducting Portion of Respiratory System

12-2 Respiratory Portion of Respiratory System
PLATE 12-1
12-2
12-3
12-4
12-5
12-6

Olfactory Mucosa, Larynx
Trachea
Respiratory Epithelium and Cilia, Electron Microscopy
Bronchi, Bronchioles
Lung Tissue
Blood-Air Barrier, Electron Microscopy

CHAPTER 13 Digestive System I
GRAPHIC 13-1 Tooth and Tooth Development
13-2 Tongue and Taste Bud
PLATE 13-1
13-2
13-3
13-4
13-5
13-6
13-7
13-8
13-9

Lip
Tooth and Pulp

Periodontal Ligament and Gingiva
Tooth Development
Tongue
Tongue and Palate
Teeth and Nasal Aspect of the Hard Palate
Teeth Scanning Electron Micrograph of Enamel
Teeth Scanning Electron Micrograph of Dentin

CHAPTER 14 Digestive System II
GRAPHIC 14-1 Stomach and Small Intestine
14-2 Large Intestine
PLATE 14-1
14-2
14-3
14-4
14-5
14-6
14-7
14-8

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Esophagus
Stomach
Stomach
Duodenum
Jejunum, Ileum
Colon, Appendix
Colon, Electron Microscopy
Colon, Scanning Electron Microscopy

254
262
263
264
266
268
270
272

276
284
285
286
288
290
292
294
296

300
308
309
310
312
314
316
318
320
322

324
325

328
336
337
338
340
342
344
346
348
350
351

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CONTENTS

CHAPTER 15 Digestive System III
GRAPHIC 15-1 Pancreas
15-2 Liver
PLATE 15-1
15-2
15-3
15-4
15-5
15-6
15-7

Salivary Glands
Pancreas
Liver
Liver, Gallbladder
Salivary Gland, Electron Microscopy
Liver, Electron Microscopy
Islet of Langerhans, Electron Microscopy

CHAPTER 16 Urinary System
GRAPHIC 16-1 Uriniferous Tubules
16-2 Renal Corpuscle
PLATE 16-1
16-2
16-3
16-4
16-5
16-6

Kidney, Survey and General Morphology
Renal Cortex
Glomerulus, Scanning Electron Microscopy
Renal Corpuscle, Electron Microscopy
Renal Medulla
Ureter and Urinary Bladder

CHAPTER 17 Female Reproductive System
GRAPHIC 17-1 Female Reproductive System
17-2 Placenta and Hormonal Cycle
PLATE 17-1

17-2
17-3
17-4
17-5
17-6
17-7
17-8

Ovary
Ovary and Corpus Luteum
Ovary and Oviduct
Oviduct, Light and Electron Microscopy
Uterus
Uterus
Placenta and Vagina
Mammary Gland

CHAPTER 18 Male Reproductive System
GRAPHIC 18-1 Male Reproductive System
18-2 Spermiogenesis
PLATE 18-1
18-2
18-3
18-4
18-5

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Testis
Testis and Epididymis

Epididymis, Ductus Deferens, and Seminal Vesicle
Prostate, Penis, and Urethra
Epididymis, Electron Microscopy

xvii

356
364
365
366
368
370
372
374
376
377

380
390
391
392
394
396
397
398
400

404
414
415

416
418
420
422
424
426
428
430

434
440
441
442
444
446
448
450

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xviii

CONTENTS

CHAPTER 19 Special Senses
GRAPHIC 19-1 Eye
19-2 Ear
PLATE 19-1
19-2

19-3
19-4
19-5
19-6
Appendix
Index

Gartner & Hiatt_FM.indd xviii

Eye, Cornea, Sclera, Iris, and Ciliary Body
Retina, Light and Scanning Electron Microscopy
Fovea, Lens, Eyelid, and Lacrimal Glands
Inner Ear
Cochlea
Spiral Organ of Corti

454
462
463
464
466
468
470
472
474
479
484

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Sixth Edition

Color Atlas and Text of

Histology

Gartner & Hiatt_Chap01.indd 1

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1

THE CELL

CHAPTER OUTLINE
Graphics

Fig. 4

Graphic 1-1 The Cell p. 12
Graphic 1-2 The Organelles p. 13
Graphic 1-3 Membranes and Membrane
Trafficking p. 14
Graphic 1-4 Protein Synthesis and Exocytosis p. 15

Plate 1-3
Fig. 1
Fig. 2

Tables
Table 1-1
Table 1-2
Table 1-3
Table 1-4

Functions and Examples of
Heterotrimeric G Proteins
Ribosome Composition
Major Intermediate Filaments
Stages of Mitosis

Plates
Plate 1-1
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Plate 1-2
Fig. 1
Fig. 2
Fig. 3

Typical Cell p. 16
Cells
Cells
Cells
Cells
Cell Organelles and Inclusions p. 18

Nucleus and Nissl bodies. Spinal cord.
Human
Secretory products. Mast cell
Zymogen granules. Pancreas

Fig. 3
Fig. 4
Plate 1-4
Fig. 1
Fig. 2
Fig. 3
Plate 1-5
Fig. 1
Plate 1-6
Fig. 1
Plate 1-7
Fig. 1
Plate 1-8
Fig. 1
Plate 1-9

Mucous secretory products.
Goblet cells
Cell Surface Modifications p. 20
Brush border. Small intestine
Cilia. Oviduct
Stereocilia. Epididymis
Intercellular bridges. Skin
Mitosis, Light and Electron Microscopy
(EM) p. 22

Mitosis. Whitefish blastula
Mitosis. Whitefish blastula
Mitosis. Mouse (EM)
Typical Cell, Electron Microscopy
(EM) p. 24
Typical cell. Pituitary (EM)
Nucleus and Cytoplasm, Electron
Microscopy (EM) p. 26
Nucleus and cytoplasm. Liver (EM)
Nucleus and Cytoplasm, Electron
Microscopy (EM) p. 28
Nucleus and cytoplasm. Liver (EM)
Golgi Apparatus, Electron Microscopy
(EM) p. 30
Golgi apparatus, (EM)
Mitochondria, Electron Microscopy
(EM) p. 32

2

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THE CELL

C

ells not only constitute the basic units of the

human body but also function in executing all
of the activities that the body requires for its
survival. Although there are more than 200 different
cell types, most cells possess common features, which
permit them to perform their varied responsibilities.
The living component of the cell is the protoplasm,
which is subdivided into the cytoplasm and the nucleoplasm (see Graphics 1-1 and 1-2). The protoplasm
also contains nonliving material such as crystals and
pigments.

CYTOPLASM
Plasmalemma
Cells possess a membrane, the plasmalemma, that provides a selective, structural barrier between the cell and
the outside world. This phospholipid bilayer with integral and peripheral proteins and cholesterol embedded
in it functions
• in cell-cell recognition,
• in exocytosis and endocytosis,
• as a receptor site for signaling molecules, such as G
proteins (Table 1-1), and
• as an initiator and controller of the secondary messenger system.
Materials may enter the cell by several means, such as
• pinocytosis (nonspecific uptake of molecules in an
aqueous solution),
• receptor-mediated endocytosis (specific uptake of
substances, such as low density lipoproteins), or
• phagocytosis (uptake of particulate matter).
Secretory products may leave the cell by two means, constitutive or regulated secretion.
• Constitutive secretion, using non–clathrin-coated vesicles, is the default pathway that does not require an
extracellular signal for release, and thus, the secretory
product (e.g., procollagen) leaves the cell in a continuous fashion.

• Regulated secretion requires the presence of clathrincoated storage vesicles whose contents (e.g., pancreatic enzymes) are released only after the initiation of
an extracellular signaling process.
The fluidity of the plasmalemma is an important factor in the processes of membrane synthesis, endocytosis, exocytosis, as well as in membrane trafficking (see
Graphic 1-3)—conserving the membrane as it is transferred through the various cellular compartments. The
degree of fluidity is influenced

Gartner & Hiatt_Chap01.indd 3

3

• directly by temperature and the degree of unsaturation of the fatty acyl tails of the membrane phospholipids and
• indirectly by the amount of cholesterol present in the
membrane.
Ions and other hydrophilic molecules are incapable of
passing across the lipid bilayer; however, small nonpolar
molecules, such as oxygen and carbon dioxide, as well as
uncharged polar molecules, such as water and glycerol,
all diffuse rapidly across the lipid bilayer. Specialized
multipass integral proteins, known, collectively, as membrane transport proteins, function in the transfer of substances such as ions and hydrophilic molecules across the
plasmalemma. There are two types of such proteins: ion
channels and carrier proteins. Transport across the cell
membrane may be
• passive down an ionic or concentration gradient
(simple diffusion) or
• facilitated diffusion via ion channel or carrier proteins
(no energy required) or
• active only via carrier proteins (energy required, usually against a gradient).
Ion channel proteins possess an aqueous pore and may be
ungated or gated. The former are always open, whereas
gated ion channels require the presence of a stimulus

(alteration in voltage, mechanical stimulus, presence of
a ligand, G protein, neurotransmitter substance, etc.)
that opens the gate. These ligands and neurotransmitter
substances are types of signaling molecules. Signaling
molecules are either hydrophobic (lipid soluble) or
hydrophilic and are used for cell-to-cell communication.
• Lipid-soluble molecules diffuse through the cell
membrane to activate intracellular messenger systems
by binding to receptor molecules located in either the
cytoplasm or the nucleus.
• Hydrophilic signaling molecules initiate a specific
sequence of responses by binding to receptors (integral proteins) embedded in the cell membrane.
Carrier proteins, unlike ion channels, can permit the passage of molecules with or without the expenditure of
energy. If the material is to be transported against a concentration gradient, then carrier proteins can utilize ATPdriven methods or sodium ion concentration differentials
to achieve the desired movement. Unlike ion channels,
the materials to be transported bind to the internal aspect
of the carrier protein. The material may be transported
• individually (uniport) or
• in concert with another molecule (coupled transport)
and the two substances may travel
in the same direction (symport) or
in opposite directions (antiport).

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4

THE CELL

TABLE 1-1 • Functions and Examples of Heterotrimeric G Proteins*
Type

Function

Examples

Gs

Activates adenylate cyclase, leading to formation of
cAMP thus activating protein kinases

Binding of epinephrine to b-adrenergic receptors increases cAMP levels in cytosol.

Gi

Inhibits adenylate cyclase, preventing formation of
cAMP, thereby protein kinases are not activated

Binding of epinephrine to a2-adrenergic receptors decreases cAMP levels in cytosol.

Gq

Activates phospholipase C, leading to formation of inositol triphosphate and diacylglycerol, permitting the
entry of calcium into the cell which activates protein
kinase C

Binding of antigen to membrane-bound IgE
causes the release of histamine by mast
cells.

Go

Opens K+ channels, allowing potassium to enter the cell
and closes Ca2+ channels thereby calcium movement
in or out of the cell is inhibited

Inducing contraction of smooth muscle

Golf

Activates adenylate cyclase in olfactory neurons which
open cAMP-gated sodium channels

Binding of odorant to G protein–linked receptors initiates generation of nerve impulse.

Gt

Activates cGMP phosphodiesterase in rod cell membranes, leading to hydrolysis of cGMP resulting in the
hyperpolarization of the rod cell plasmalemma

Photon activation of rhodopsin causes rod
cells to fire.

G12/13

Activates Rho family of GTPases which control the formation of actin and the regulation of the cytoskeleton

Facilitating cellular migration

*cAMP, cyclic adenosine monophosphate; cGMP, cyclic guanosine monophosphate; IgE, immunoglobulin E

Cells possess a number of distinct organelles, many of
which are formed from membranes that are similar to
but not identical with the biochemical composition of
the plasmalemma.

Mitochondria
Mitochondria (see Graphic 1-2) are composed of
an outer and an inner membrane with an intervening compartment between them known as the intermembrane space. The inner membrane is folded to
form flat, shelf-like structures (or tubular in steroidmanufacturing cells) known as cristae and encloses a
viscous fluid-filled space known as the matrix space.
Mitochondria
• function in the generation of ATP, utilizing a chemiosmotic coupling mechanism that employs a specific
sequence of enzyme complexes and proton translocator systems (electron transport chain and the ATPsynthase containing elementary particles) embedded
in their cristae
• generate heat in brown fat instead of producing ATP
• also assist in the synthesis of certain lipids and proteins; they possess the enzymes of the TCA cycle
(Krebs’ cycle), circular DNA molecules, and matrix
granules in their matrix space
• increase in number by undergoing binary fission.

Gartner & Hiatt_Chap01.indd 4

Ribosomes
Ribosomes are small, bipartite, nonmembranous organelles
that exist as individual particles that do not coalesce with
each other until protein synthesis begins. The two subunits
are of unequal size and constitution. The large subunit is
60S and the small subunit is 40S in size (see Table 1-2). Each

subunit is composed of proteins and r-RNA, and together
they function as an interactive “workbench” that not only
provides a surface upon which protein synthesis occurs but
also as a catalyst that facilitates the synthesis of proteins.

Endoplasmic Reticulum
The endoplasmic reticulum is composed of tubules, sacs,
and flat sheets of membranes that occupy much of the

TABLE 1-2 • Ribosome Composition
Subunit

Size

Number of Proteins

Types of rRNA

Large

60S

49

5S
5.8S
28S

Small

40S

33

18S

rRNA, ribosomal ribonucleic acid; S, Svedberg units

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THE CELL

intracellular space (see Graphic 1-2). There are two types
of endoplasmic reticula, smooth and rough.
• Smooth endoplasmic reticulum functions in the
synthesis of cholesterols and lipids as well as in the
detoxification of certain drugs and toxins (such as barbiturates and alcohol). Additionally, in skeletal muscle cells, this organelle is specialized to sequester and
release calcium ions and thus regulate muscle contraction and relaxation.
• The rough endoplasmic reticulum (RER), whose cytoplasmic surface possesses receptor molecules for ribosomes and signal recognition particles (SRPs) (known
as ribophorins and docking protein, respectively), is
continuous with the outer nuclear membrane. The
RER functions in the synthesis and modification of
proteins that are to be packaged, as well as in the synthesis of membrane lipids and proteins.
Protein synthesis requires the code-bearing mRNA, amino
acid–carrying tRNAs, and ribosomes (see Graphic 1-4).
Proteins that will not be packaged are synthesized on
ribosomes in the cytosol, whereas noncytosolic proteins
(secretory, lysosomal, and membrane proteins) are synthesized on ribosomes on the rough endoplasmic reticulum. The complex of mRNA and ribosomes is referred to
as a polysome.

• The signal hypothesis states that mRNAs that code
for noncytosolic proteins possess a constant initial
segment, the signal codon, which codes for a signal
protein.
• As the mRNA enters the cytoplasm, it becomes associated with the small subunit of a ribosome. The small
subunit has a binding site for mRNA as well as three
binding sites (A, P, and E) for tRNAs.
1. Once the initiation process is completed, the start
codon (AUG for the amino acid methionine)
is recognized, and the initiator tRNA (bearing
methionine) is attached to the P site (peptidyltRNA-binding site), the large subunit of the ribosome, which has corresponding A, P, and E sites,
becomes attached, and protein synthesis may
begin.
2. The next codon is recognized by the proper acylated
tRNA, which then binds to the A site (aminoacyltRNA binding site). Methionine is uncoupled from
the initiator tRNA (at the P site), and a peptide
bond is formed between the two amino acids
(forming a dipeptide) so that the tRNA at the P site
loses its amino acid and the tRNA at the A site now
has two amino acids attached to it. The formation
of this peptide bond is catalyzed by the enzyme
peptidyl transferase, a part of the large ribosomal
subunit.

Gartner & Hiatt_Chap01.indd 5

5

3. As the peptide bond is formed, the large subunit
shifts in relation to the small subunit and the attached

tRNA’s wobble just enough to cause them to move
just a little bit, so that the initiator tRNA (that lost its
amino acid at the P site) moves to the E site (exit site)
and the tRNA that has two amino acids attached to it
moves from the A site to the P site freeing the A site.
4. As this shifting occurs, the small ribosomal subunit
moves the space of a single codon along the mRNA,
so that the two ribosomal subunits are once again
aligned with each other and the A site is located
above the next codon on the mRNA strand.
5. As a new tRNA with its associated amino acid occupies the A site (assuming that its anticodon matches
the newly exposed codon of the mRNA), the initiator
RNA drops off the E site, leaving the ribosome. The
dipeptide is uncoupled from the tRNA at the P site,
and a peptide bond is formed between the dipeptide
and the new amino acid, forming a tripeptide.
6. The empty tRNA again moves to the E site to fall
off the ribosome, as the tRNA bearing the tripeptide
moves from the A site to the P site. In this fashion, the
peptide chain is elongated to form the signal protein.
The cytosol contains proteins known as signal recognition particles (SRPs).
• SRP binds to the signal protein, inhibits the continuation of protein synthesis, and the entire polysome proceeds to the RER.
• A signal recognition particle receptor, a transmembrane protein located in the membrane of the RER,
recognizes and properly positions the polysome.
• The docking of the polysome results in the movement
of the SRP-ribosome complex to a protein translocator, a pore in the RER membrane.
• The large subunit of the ribosome binds to and forms
a tight seal with the protein translocator, aligning the
pore in the ribosome with the pore in the protein
translocator.

• The signal recognition particle and SRP receptor leave
the polysome, permitting protein synthesis to resume,
and the forming protein chain can enter the RER cisterna through the aqueous channel that penetrates the
protein translocator.
• During this process, the enzyme signal peptidase,
located in the RER cisterna, cleaves signal protein
from the growing polypeptide chain.
• Once protein synthesis is complete, the two ribosomal
subunits fall off the RER and return to the cytosol.
The newly synthesized protein is modified in the RER
by glycosylation, as well as by the formation of disulfide
bonds, which transforms the linear protein into a globular form.

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