Upload
others
View
7
Download
0
Embed Size (px)
Citation preview
Histology 2 – muscle, nerve and reproductive tissues
1. Muscle tissue – organization
2. Classification of muscle tissue:
smooth muscle tissue
striated (skeletal) muscle tissue
cardiac (heart) muscle tissue
3. Nerve tissue – characteristics
4. Nerve cells (neurons)
5. Neuroglial cells
6. Reproductive tissue:
male germ cells – spermatozoa
female germ cells – ova
Prof. Dr. Nikolai Lazarov 2
Muscle tissue
body movements
digestion
blood circulation
respiratory movements
other movement activities, incl. cellular contraction
succession of relax and contraction:
transformation of chemical into mechanical energy
Textus muscularis: cells – myocytes extracellular matrix
Prof. Dr. Nikolai Lazarov 3
Properties of muscle tissue
irritability the ability of a muscle to respond
to a stimulus
conductivity the ability of a muscle
to conduct electrical impulses across the membrane
contractility the ability of a muscle to shorten
and to produce energy
extensibility the ability of a muscle to lengthen
beyond its resting length
elasticity the ability of a muscle to return to
its original length without damage
NB: muscles can only pull or contract, not push!
Prof. Dr. Nikolai Lazarov 4
Muscle fibers – myofibers
muscle cells = myocytes (leiomyocytes, rhabdomyocytes, cardiomyocytes): elongated, cylindrical or fusiform = myofibers sarcolemma = plasmalemma sarcoplasm = cytoplasm sarcoplasmic reticulum =
smooth endoplasmic reticulum sarcosomes = mitochondria myoglobin: oxygen-binding protein connective tissue components:
endomysium (Gr. endon, within + mys, muscle) perimysium (Gr. peri, around, near + mys) epimysium (Gr. epi, upon + mys)
Gr. sarkos, flesh
myoepithelial cells pericytes myofibroblasts in healing wounds myoid cells of the testis
Prof. Dr. Nikolai Lazarov 5
Types of muscle tissue
Prof. Dr. Nikolai Lazarov 6
Smooth muscle tissue
origin: mesenchyme
involuntary: ANS innervation
tonus
peristalsis
nonstriated
in the walls of hollow and tubular organs: blood vessels
(with exception of capillaries)
alimentary canal
respiratory tract
urogenital system
associated with hair follicles in the skin (arrector pili muscles)
Characteristics: Textus muscularis nonstriatus (glaber)
Prof. Dr. Nikolai Lazarov 7
Smooth muscle tissue
leiomyocyte (Gr. leios, smooth)
shape: fusiform or “spindle-shaped”
length: 30-500 µm
thickness: 5-10 µm
Prof. Dr. Nikolai Lazarov 8
Smooth muscle types
visceral (single-unit) smooth muscles in the walls of hollow organs small blood vessels
• relatively poor nerve supply • abundant gap junctions
function in syncytial fashion
multi-unit smooth muscles large arteries upper respiratory tract muscles of hair follicles iris and ciliary body of the eye
• rich nerve supply
• innervate individual cells
• allow for fine control
• provide very precise and graded contractions
two types of smooth muscle:
Prof. Dr. Nikolai Lazarov 9
Skeletal muscle tissue
the most abundant tissue in the vertebrate body – 40% of the body mass
origin: mesoblast (myotomes)
voluntary: CNS innervation strong, quick voluntary control
of contraction/relaxation
cross-striated
skeletal muscles
initial and end parts of the digestive tract
muscles of the head (incl. eye, ear)
muscles of respiration
Textus muscularis striatus (skeletalis)
Prof. Dr. Nikolai Lazarov 10
Skeletal muscle tissue
rhabdomyocyte (Gr. rhabdo, striped)
shape: elongated, cylindrical
length: 1-40 cm
diameter: 10-100 µm
numerous nuclei: 10-100/cell, located right up under the plasma membrane
Prof. Dr. Nikolai Lazarov 11
Organization of skeletal muscle
Skeletal muscle
Muscle fasciculus
Muscle fiber
Myofibril
Myofilaments
Prof. Dr. Nikolai Lazarov 12
Sarcomere
А band (anisotropic, i.e., birefringent in polarized light)
H zone (from the German “Hell”, bright)
М line (mesophragm, "Mittel", middle of the sarcomere): creatine kinase
I band (isotropic, does not alter polarized light, monorefrigent)
Z disk (“Zwischenscheibe”, the band in between the I bands) = telophragm: α-actinin
Sarcomere (Gr. sarkos + meros, part):
length: 2-3 µm (~2.5 µm) – extends from Z line to Z line
Prof. Dr. Nikolai Lazarov 13
Myofilaments thin (actin) filaments – 1 µm long/8 nm wide:
actin – long filamentous polymers of F-actin; • 2 twisted strands of G-actin – globular monomer, 5.6 nm in diameter
tropomyosin – 40 nm in length extending over 7 G-actin molecules • 2 polypeptide chains
troponin – ТnT, TnI, TnC at intervals of 40 nm, attached to tropomyosin
thick (myosin) filaments – 1.6 µm long/15 nm wide: head (ATPase activity) + proximal 60 nm of tail = heavy meromyosin distal 90 nm of the tail = light meromyosin 2 identical heavy chains and 2 pairs of light chains
Prof. Dr. Nikolai Lazarov 14
Mechanism of contraction
rigor mortis
Sliding Filament Hypothesis: Huxley
Prof. Dr. Nikolai Lazarov 15
Types of muscle fibers
Red fibers (slow oxydative) – type I
White fibers (fast glycolytic) – type IIb
Intermediate (slow oxydative) – type IIa
Prof. Dr. Nikolai Lazarov 16
Cardiac muscle tissue
origin: mesenchyme involuntary: ANS
quick continuous automatic contraction conduction system
striated in the wall of the
heart (myocardium) some large vessels
Textus muscularis striatus cardiacus
Prof. Dr. Nikolai Lazarov 17
cardiomyocyte (Gr. cardia, heart)
three types of cardiac myocytes: contractile, conductive, secretory
shape: cylindrical, bifurcated
length: 85-100 µm
diameter: 15-20 µm
only 1 (or 2) centrally located pale-staining nuclei
delicate sheath of endomysial connective tissue containing a rich capillary network
Cardiac muscle tissue
Prof. Dr. Nikolai Lazarov 18
Myoepithelial cells
basket cells:
sweat gland
mammary gland
lacrimal gland
salivary glands
Prof. Dr. Nikolai Lazarov 19
Prof. Dr. Nikolai Lazarov 20
Nerve tissue
main functions: sensing stimuli and
creating, analyzing, and integrating information
regulates and controls body functions
provides the unity with the environment
properties: irritability
capacity to respond to a stimulus – generation of a nerve impulse
conductivity capacity to transfer the response
throughout the neuron by the plasma membrane
Textus nervosus: cells – nerve and glial cells extracellular matrix
Prof. Dr. Nikolai Lazarov 21
neuron – more than 10 billion in the human NS cell body (perikaryon) axon – Golgi type І and ІІ neurons dendrites
Nerve cells
Prof. Dr. Nikolai Lazarov 22
perikaryon (Gr. peri, around + karyon, nucleus) a trophic and receptive center of the neuron diameter – 20-40 µm (4-120 µm) shape – pyramidal, stellate, fusiform, flask-shaped etc.
Cell body
composition: large, euchromatic nucleus with
a prominent nucleolus organelles:
Nissl bodies Golgi complex mitochondria microtubules neurofilaments lipofuscin and
neuromelanin
Prof. Dr. Nikolai Lazarov 23
axon (Lat. axis, axle or pivot) length – 1 mm-100 cm diameter – 0.2-20 µm
Nerve processes
structure: axon hillock initial segment collateral branches axonal ending (terminal)
synapse axolemma axoplasm:
ribosomes – occasionally absence of rER and GA
axonal transport: slow stream – 0.2 µm/day
anterograde flow fast stream – 10-40 cm/day
anterograde and retrograde flow
Prof. Dr. Nikolai Lazarov 24
dendrites (Gr. dendron, tree) number – variable, most frequently 5-15 80-90% of the surface
Nerve processes
structure: short, dendritic tree dendrite spines dendritic cytoplasm:
Nissl bodies mitochondria neurofilaments microtubules absence of Golgi complex
Prof. Dr. Nikolai Lazarov 25
Basic neuronal types
morphological classes: pseudounipolar neurons bipolar neurons multipolar neurons
functional classes: motor (efferent) neurons
sensory (afferent) neurons interneurons
Prof. Dr. Nikolai Lazarov 26
structure: presynaptic component,
axon terminal presynaptic membrane presynaptic grid mitochondria synaptic vesicles –
(20-65 nm) transmitters
synaptic cleft (20-30 nm)
postsynaptic membrane postsynaptic thickening receptors
C.S. Sherrington 1857–1952
Synapses synapse (Gr. synaptein, to join together)
way of transmission: electrical synapses chemical synapses
Types of synapses
contacting structures: axosomatic synapses axodendritic axoaxonic dendrodendritic somatodendritic etc.
morphologically: asymmetrical (type I) – Glu symmetrical (type IІ) – GABA
functionally: excitatory synapses inhibitory synapses
atypical synapses: reciprocal dendrodendritic
serial synapses “ribbon” synapse synaptic glomeruli
27 Prof. Dr. Nikolai Lazarov
Prof. Dr. Nikolai Lazarov 28
Neurotransmitters
types of neurotransmitters: classical transmitters
amino acids biogenic amines other major transmitters – ACh
neuroactive peptides (neuropeptides) atypical neural messengers:
arachidonic acid derivatives purines
adenosine, ATP gaseous – NO, CO
postsynaptic effect: excitatory
acetylcholine glutamate aspartate
inhibitory monoamines GABA and glycine
neurotransmitters – criteria neuromodulators
Transporters: integral proteins –
Na+ transport symporters
Transporters and receptors
Transmitter receptors: ionotropic – transmitter-gated ion channels
for ACh, GABA, Gly, SER for glutamate
• NMDA-receptors • non-NMDA-receptors (AMPA and kainate)
metabotropic receptors G-protein-coupled receptors
• muscarinic ACh receptors • - and -adrenergic receptors • receptors for Glu, SER, GABA, neuropeptides
tyrosine kinases receptor family guanylate cyclase receptors cytokine receptors
autoreceptors
Acetylcholinesterase (AChE)
Prof. Dr. Nikolai Lazarov 29
Prof. Dr. Nikolai Lazarov 30
Prof. Dr. Nikolai Lazarov 31
Arvid Carlsson, Paul Greengard and Eric Kandel for their discoveries concerning "signal transduction in the nervous system"
Arvid Carlsson, Department of Pharmacology, Göteborg University, Sweden,
is rewarded for his discovery that dopamine is a brain transmitter of great
importance for our ability to control movements that has led to the realization
that Parkinson's disease is caused by a lack of dopamine in certain parts of the
brain.
Paul Greengard, Laboratory of Molecular and Cellular
Science, Rockefeller University, New York, USA, is
rewarded for his discovery of how dopamine and a
number of other transmitters exert their action in the
nervous system.
Eric Kandel, Center for Neurobiology and Behavior, Columbia
University, New York, USA, is rewarded for his discoveries of how
the efficiency of synapses can be modified, and which molecular
mechanisms that take part.
Prof. Dr. Nikolai Lazarov 32
Neuroglia
central gliocytes – neural tube:
astrocytes
oligodendrocytes
ependymal cells
microglial cells
peripheral gliocytes – neural crest:
Schwann cells (neurolemmocytes)
satellite cells of Cajal (syn: mantle cells or amphicytes)
Glial cells – glioblastic origin: central – macroglia and microglia (in CNS) peripheral – in PNS
Prof. Dr. Nikolai Lazarov 33
Central gliocytes
oligodendrocytes
large light
medium-sized
small dark – ¼ of the light cells
myelin-forming cells in the CNS
ependymal cells – neural crest
line the ventricles of the brain and central canal of the spinal cord
absorption and secretion of cerebrospinal fluid (liquor)
tanycytes (ependymal astrocytes)
microglia – 15% of the total cells of CNS
non-dividing cells
derived from monocytes
role of macrophages (mononuclear phagocyte system in nervous tissue)
astrocytes protoplasmic fibrous astrocytes
(Gr. astron – star)
(Gr. oligos – small)
Prof. Dr. Nikolai Lazarov 34
Peripheral gliocytes
neural crest origin
myelin-forming cells in the PNS
maintenance of the axon integrity
phagocytotic activity and cellular debris that allows for regrowth of PNS neuron
Schwann cells (neurolemmocytes)
satellite cells (amphicytes) in sensory and autonomic ganglia
help regulate the external chemical environment
Prof. Dr. Nikolai Lazarov 35
Nerve fiber: axon sheath derived from cells of ectodermal origin:
oligodendrocyte – CNS Schwann cell – PNS
Nerve fibers
Types of nerve fibers: unmyelinated – 0.1-2 µm diameter
both in the CNS and PNS absence of nodes of Ranvier 0.5-2 m/sec conduction velocity
myelinated – 1-20 µm both in the CNS and PNS mesaxon nodes of Ranvier internodal segment – 1-2 mm
Schmidt-Lanterman clefts 4-120 m/sec velocity
Prof. Dr. Nikolai Lazarov 36
3 main groups – Sherrington, 1906:
exteroceptors
proprioceptors
interoceptors
by sensory modality:
baroreceptors – respond to pressure
chemoreceptors – chemical stimuli
mechanoreceptors – mechanical stress
nociceptors – pain perception
thermoreceptors – temperature
(heat, cold or both)
by location:
cutaneous receptors – in the skin
muscle spindles – in the muscles
by morphology:
free nerve endings
encapsulated receptors
C.S. Sherrington
1857–1952
Sensory receptors – classification
Prof. Dr. Nikolai Lazarov 37
structure:
myelinated axon collaterals
~50 axon terminals (boutons)
• synaptic vesicles – ACh
• presynaptic membrane
sarcolemma junctional folds postsynaptic membrane
• nicotinic ACh receptors
autonomic effector endings:
sympathetic – adrenergic (NA)
parasympathetic – cholinergic (ACh)
purinergic – ATP and adenosine
do not make
specialized synaptic contacts
Effector nerve endings
myoneural junction – motor end plate:
Sex cells (gametes)
Reproductive tissue:
a separate tissue – A. Hadjiolov, 1930 kind of epithelial tissue
composition:
sex cells (gametes) – male and female
“somatic” cells
embryonic origin:
primordial germ cells (gonocytes)
formation in the epiblast – 2nd week of gestation
movement to the wall of the yolk sac – 3rd week
migration toward the developing gonads – 5th week
formation of primary sex cords
sex differentiation – male and female
gametogenesis
Prof. Dr. Nikolai Lazarov 38
Spermatogenic cells
Primary spermatocytes:
largest cells – 18-20 µm
enter a prolonged prophase of first meiotic division (22 days) – preleptotene spermatocytes
diploid – 46 (44, XY) chromosomes
23 tetrades (2n DNA)
Spermatogonia (Gr. sperma, seed + gone, generation):
about 12 µm in diameter
situated next to the basal lamina of the epithelium
type A – stem cells
type Ad cells – divide rarely
type Ap cells – mitotic division
type B – progenitor cells (mitotic division – 16 days)
Prof. Dr. Nikolai Lazarov 39
Spermatogenic cells
Secondary spermatocytes:
smaller cells – 12 µm
in meiosis II (16 days) – prespermatids
haploid – 23 chromosomes
normal amount of DNA (2n)
Prof. Dr. Nikolai Lazarov 40
Spermatids:
small cells – 7-8 µm
early spermatids – oval in shape
late spermatids – elongated
juxtaluminal location
connected by cytoplasmic bridges
haploid – contain 23 chromosomes
reduced amount of DNA – 1n
do not divide – undergo spermiogenesis
3 phases:
Golgi phase
proacrosomal granules
acrosomal phase
acrosomal vesicle
acrosome – hydrolytic enzymes:
• hyaluronidase
• neuraminidase
• acid phosphatase
• acrosin (zonalysin)
maturation phase
residual bodies are shed
formation of spermatozoa
release of mature spermatozoa
spermiation
Spermiogenesis
spermatid mature spermatozoon:
process duration – 24 days
Prof. Dr. Nikolai Lazarov 41
Sperm structure: head – length 5 µm; wide 3 µm; apex 1 µm
condensed nucleus, 1-2 vacuoles acrosomal cap
neck – length 0.3 µm; diameter 1 µm
covered by plasmalemma basal body – proximal centriole
tail – flagellum middle piece – length 5-7 µm;
diameter ~1 µm • axonemal complex • spiraled mitochondria
principal piece – 45-50 µm
• longitudinal and circumferential fibrous sheath
end piece – 5-7 µm • axoneme • surrounding plasmalemma
Spermatozoon (Gr. σπέρμα, seed + ζῷον, living being):
mature male gamete
first observed in 1677 total length – 58-67 µm
Spermatozoon
Anton van Leeuwenhoek
(1632-1723)
Prof. Dr. Nikolai Lazarov 42
Female gametes
Female sex cells: oocytes (Gr. oon, egg + kytos)
Prof. Dr. Nikolai Lazarov 43
follicular cells flat epithelial cells defending function secretory role – liquor folliculi endocrine secretion – estrogens ovulation lutein cells – progesterone
thecal cells (thecocytes) build up the theca interna steroid-secreting cells – estrogens
ovulation lutein cells – progesterone
interstitial cells active thecal cells in small groups throughout
the cortical stroma around vessels source of ovarian androgens
hilus cells in ovarian medulla similar to Leydig cells in testis produce testosterone
primary oocytes: medium-sized cells – 25-30 µm
prophase of the first meiotic division
diploid
secondary oocytes: larger in size – 40-50 µm
2nd meiotic division (metaphase)
haploid – 23 chromosomes
normal amount of DNA (2n)
ovum (mature oocyte): large cell – 50-150 µm large nucleus with haploid number of chromosomes
oolemma with microvilli acidophilic PAS-positive zona pellucida,
glycosaminoglycans, glycoproteins and sialic acid, source of fertilizine perivitelline space
oogonia – mitotically active cells reduction in number – cell death primordial follicles
Oocytes
Prof. Dr. Nikolai Lazarov 44
prenatal stage:
period of proliferation – gonocytes
oogonia – 7 million/5th month
primary oocytes – 700000-2 million
postnatal stage:
growth – primary oocytes
remain in prophase of meiosis I (diplotene stage)
oocyte maturation inhibitor
maturation – secondary oocytes
peculiarities of oogenesis: first meiotic division (meiosis I) begins during fetal life and is
completed just before ovulation meiosis II is completed only if the oocyte is fertilized one mature oocyte (ovum) and three polar bodies are formed
from one oogonium different structural peculiarities in different animal species
Oogenesis
oogonia mature oocytes (ova):
in female gonads – ovaries
Prof. Dr. Nikolai Lazarov 45
Abnormal gametes
Prof. Dr. Nikolai Lazarov 46
in humans and in most mammals:
one ovarian follicle occasionally contains two or
three clearly distinguishable primary oocytes
usually degenerate
before reaching maturity
twins or triplets
one primary oocyte contains
two or three nuclei
die before reaching maturity
abnormal spermatozoa –
up to 10% of all spermatozoa
abnormal head or tail
giants or dwarfs
sometimes are joined
lack normal motility and
probably do not fertilize oocytes
Thank you… Prof. Dr. Nikolai Lazarov 47