General Histology Dr. Ashraf Shamia Al Azhar University Gaza Uplode by Lama K El Banna

1. Dr.Ashraf Y. Shamia
M.D.S of Oral Pathology
Al-Azhar University –Gaza
Dr.Haydar Abd El-Shafi Faculty of Dentistry
Muscular Tissue

2. • Differences between the three types of muscle:
• 1-Skeletal (Striated) Muscle
• 2-Cardiac Muscle
• 3-Smooth Muscle

3. Muscular tissue
Origin:
it arises from the Mesoderm.Mesoderm.

4. Muscular tissue
Types: according to the histological structure
and physiological requirements, muscles are of
3 types:
• 1-Skeletal (Striated) Muscle
• 2-Cardiac Muscle
• 3-Smooth Muscle

5. Origin

7. function

8. •Note :
• Pharynx
• esophagus
• cremasteric muscle
• are non-voluntary skeletal muscle
• except the ciliary muscle & some bladder
muscles which are voluntary smooth
muscle .

9. Cell size

10. Cell shape

11. sarcolemma

12. SMOOTH MUSCLE
• Dense bodies are present on the inner aspect of the
cell membrane, called dense plaques, other dense
bodies are present in the cytoplasm.
• Invaginations of the sarcolemma to the interior, along
the surface are called caveolae. No T-tubules & no
triad tubular system.

13. Nucleus

19. Branching

20. Striations

21. Intercalated disk

22. The Intercalated Disck
• It is a transverse line that crosses the fibers at intervals.
• It is formed of 2 cell membranes of 2 adjacent cardiac myocytes, at
the level of Z-line, the two cells are joined end to end with minimal
intercellular space (15-20 nm), not in a straight line but in a step-
wise manner.

23. CARDIAC MUSCLE
• These membranes are joined by 3 types of junctional
complexes:
1- Desmosomes: very firm attachment, located in the
vertical segment of the step-like membrane of
myocytes, which prevent their separation.
2- Adherent junctions (fascia adherens): help in
transmitting contraction.

24. • 3- Gap junctions: located in the longitudinal
segment of the membrane disc, permit diffusion of
ions through the pores, which permits coordination of
the activities of the myocytes, so act as physiological
syncytium.

25. • junctions are present to allow rapid communication
between cardiac muscle
• cells and passage of impulses from one cell to the
adjacent one.

26. • The Valves of the Heart: They are folds of the
endocardium (simple squamous
• endothelium), containing a middle supporting
layer of dense fibrous C.T., rich in
• collagen and elastic fibers. This layer is
thickened at the base of mitral &
• tricuspid valves. The C.T. is rich in histiocytes
(macrophages), to engulf any
• microorganism in the blood.

27. SMOOTH MUSCLE
• Gap junctions are found between the
adjacent fibers (to facilitate the spread of
excitation).

28. sarcoplasm

29. Longitudenal section

30. Transverse section

31. Myofibrils

33. Mitochondria (sarcosomes):

34. Golgi apparatus

35. Inclusions

36. Heart
• Atrial natriuretic polypeptide (ANP):
membrane bound dense
• granules present in atrial muscle cells.
They contains peptide hormone-like
factor, which is involved in regulation of
blood volume and electrolyte composition
of the extracellular fluid. It participates in
lowering the blood pressure.

37. Sarcoplasmic reticulum:
• It is a modification of the smooth endoplasmic
reticulum which is very well developed. It is formed
of membrane bounded tubules that form a network
around the myofibrils. At the level of the junction
between the A & I bands, in adjacent myofibrils, it
shows dilatedt erminal cisternae that run in planes at
right angles to the long axis of myofibrils, and form
rings around them.

38. • It is important for Ca++ pump, as it responds to nerve
impulses that spread over its membranes, changing
its polarization. This leads to the release of Ca ions
that triggers contraction. It is also the site of storage
of Ca during relaxation.

43. T- TUBULES

44. Differences between the three types of muscle:

45. microscopic slides of
Skeletal muscle

46. Skeletal muscle fibers

48. Skeletal muscle fibers
longitudinal section

49. Skeletal muscle fibers
longitudinal section

50. Skeletal muscle fibers
longitudinal section

51. Skeletal muscle fiber
longitudinal section

52. Skeletal muscle fibers
longitudinal section
1 Nucleus of a skeletal muscle fiber
2 Endomysium
Stain: azan; magnification: × 1125

53. Skeletal muscle fibers

54. Skeletal muscle fibers

55. Skeletal muscle fibers
Transverse section

56. Skeletal muscle fibers
Transverse section

57. Skeletal muscle fibers
Transverse section
1 Nucleus in a muscle
fiber
2 Fibrocyte
3 Collagenous (dense)
connective tissue
Stain: Heidenhain iron
hematoxylin
magnification: × 1125

58. Skeletal muscle fibers
Transverse section
1 Nucleus of a skeletal muscle fiber
2 Capillary
3 Nucleus of a connective tissue cell
Semi-thin section; stain: methylene blue-azure II; magnification: × 800

59. Skeletal muscle fibers
longitudinal section
1 Endomysium
Stain: azan; magnification: × 500

60. Groups of muscle fibers surrounded by perimysium
referred to as muscle fascicles or muscle bundles

61. •microscopic slides of
cardiac muscle

62. cardiac muscle fibers

63. Cardiac muscle fibers

65. Cardiac muscle fibers

66. Cardiac muscle fibers

67. Cardiac muscle fibers

68. Cardiac muscle fibers

69. Cardiac muscle fibers

70. •microscopic slides of
smooth muscle

74. smooth muscle fibers
• With your study partners, find:
• the elongated, "cigar-shaped" nuclei of the smooth muscle cells
• the deeply eosinophilic cytoplasm of the smooth muscle cells
the intercellular spaces between the smooth muscle cells

75. smooth muscle fibers

76. smooth muscle fibers

77. smooth muscle fibers
LP- Lamina propria
SM1- Inner layer. Smooth muscle circularly
oriented and forms tight spirals.
SM2- Outermost layer. Smooth muscle
runs longitudinally.

78. smooth muscle fibers

80. Connective tissue Component:
Epimysium:
It is a dense collagenous C.T enclosing the whole muscle,
Perimysium:
It is thin, less dense, extends from the epimysium inwards to enclose each
bundle . Groups of muscle fibers surrounded by perimysium referred to as
muscle fascicles or muscle bundles
Endomysium:
It encloses each muscle fiber and unites them together. It is formed of a delicate,
highly vascular C.T., mainly reticular fibers which fuse with the basal
lamina that surrounds each fiber, which is called external lamina.

82. • epithelial membrane from inside (endocardium)
• The cardiac muscle fibers which form the bulk of the
wall are found in the middle layer of the heart
(myocardium).
• This layer is thicker in the ventricles than in the
atria. The cardiac muscles are covered by a serous
membrane from outside (epicardium)

86. Musculotendinous Junction:
• At the junction of the muscle with the tendon, the
muscle fibers stop abruptly and their sarcolemma, with
the firmly fixed endomysium, continue with the C.T.
fibers of the perimysium and epimysium.

87. Tendon:
• Tendons are formed of regular white fibrous C.T.,
which is formed of collagen fibers that are packed and
run parallel to each other.
• The fibers are arranged in the form of bundles. These
bundles are bounded by little amount of areolar C.T.,
which contains fibrocytes.

88. • Fibrocytes are called tendon cells. They appear
elongated between collagen fibers in longitudinaL
section.
• In transverse section, they appear as star shaped, as
they insinuate their processes between the bundles.

89. EM Picture of Myofibrils:

90. EM Picture of Myofibrils:
• Each myofibril shows alternative dark & light bands
• The corresponding bands in adjacent fibrils are
registered beside each other at the same level
(causing the transverse striation).
• The light bands and the dark bands are called I-bands
& A-bands, respectively.

91. • N.B. These letters stand for the terms of (Isotropic &
Anisotropic). These terms refer to the way in which
any material reflects the polarized light transmitted
through it. Some material reflect the light equally in all
directions, they are said to be isotropic, while others
which do not reflect light equally in different
directions, are anisotropic. This depends on the
elements making up the materials.

92. Muscle fiber
Muscle fiber

96. • The dark A band has a pale area in the middle called H-
zone, which is bisected by a thin M-line
• The light I band is bisected by a thin dark membrane
called Z- line
• The myofibrils are composed of smaller units called
myofilaments which are
• thin (actin microfilaments 7 nm) &
• thick (myosin filaments 15 nm).

97. • Sarcomere: is the segment of a myofibril between 2
successive Z-Iines, and it is considered the functional
unit in contraction, as this distance shortens during
contraction.

99. • The H-band represents the area in the middle of the
A-band in which actin filaments do not extend (only
myosin).
• The M-line is produced by fine interconnections
between adjacent myosin filaments.
• N.B.: The A-band is formed of myosin & actin
filaments except the H-zone The I- band is formed of
actin.

101. • The thin actin filaments are attached at one end to the Z- band,
pass through the I-band, and extend to the outer parts of the A-
band, where they interdigitate with myosin filaments.
• During contraction actin filaments glide over the myosin,
sliding more and more into the interval between myosin,
approaching the middle of the A band, leading to disappearance
of H-zone & shortening of I-band, while A- band remains
constant, with the result of shortening of sarcomeres.

102. 1 Z-band
2 I-bands (isotropic(
3 A-bands (anisotropic(
4 H-band (H-zone; Hensen’s
bands(
with M-band (M-line(
5 Mitochondria
6 Nucleus of the muscle fiber
7 Extracellular matrix with
collagen fibrils
Electron microscopy;
magnification: × 6000

108. DRAWING