Histology 2 muscle and nerve tissuesnikolai.lazarov.pro/files/pharmacy_eng/Muscle...Nerve tissue...

Histology 2 –muscle and nerve 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


Properties of muscle tissue

irritability the ability of a muscle to respond

to a stimulus

conductivity the ability of a muscle

to conduct electrical impulsesacross 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!


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


Types of muscle tissue


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)


Smooth muscle tissue

leiomyocyte (Gr. leios, smooth)

shape: fusiform or “spindle-shaped”

length: 30-500 µm

thickness: 5-10 µm


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:


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)


Skeletal muscle tissue

rhabdomyocyte (Gr. rhabdo, striped)

shape: elongated, cylindrical

length: 1-40 cm

diameter: 10-100 µm

numerous nuclei: 10-100/cell, locatedright up under the plasma membrane


Organization of skeletal muscle

Skeletal muscle

Muscle fasciculus

Muscle fiber

Myofibril

Myofilaments


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


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


Mechanism of contraction

rigor mortis

Sliding Filament Hypothesis: Huxley


Types of muscle fibers

Red fibers (slow oxydative) – type I

White fibers (fast glycolytic) – type IIb

Intermediate (slow oxydative) – type IIa


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


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


Myoepithelial cells

basket cells:

sweat gland

mammary gland

lacrimal gland

salivary glands


Nerve tissue

main functions: sensing stimuli and

creating, analyzing, and integrating information

regulates and controlsbody functions

provides the unitywith 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


neuron – more than 10 billion in the human NS cell body (perikaryon) axon – Golgi type І and ІІ neurons dendrites

Nerve cells


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


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 – occasionallyabsence of rER and GA

axonal transport: slow stream – 0.2 µm/day

anterograde flow fast stream – 10-40 cm/day

anterograde and retrograde flow


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


Basic neuronal types

morphological classes: pseudounipolar neurons bipolar neurons multipolar neurons

functional classes: motor (efferent) neurons

sensory (afferent) neurons

interneurons


structure: presynaptic component,

axon terminal presynaptic membrane presynaptic gridmitochondria synaptic vesicles –

(20-65 nm) transmitters

synaptic cleft (20-30 nm)

postsynaptic membrane postsynaptic thickening receptors

C.S. Sherrington1857–1952

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” synapsesynaptic glomeruli

27Prof. Dr. Nikolai Lazarov


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

inhibitorymonoaminesGABA 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 receptorsG-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)



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.


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


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 brainand 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)


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


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


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


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 wallof the yolk sac – 3rd week

migration toward the developing gonads – 5th week

formation of primary sex cords

sex differentiation –male and female

gametogenesis


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 thebasal 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)


Spermatogenic cells

Secondary spermatocytes:

smaller cells – 12 µm

in meiosis II (16 days) –prespermatids

haploid – 23 chromosomes

normal amount of DNA (2n)


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


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 – flagellummiddle piece – length 5-7 µm;

diameter ~1 µm• axonemal complex• spiraled mitochondria

principal piece – 45-50 µm

• longitudinal and circumferentialfibrous 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)


Female gametes

Female sex cells: oocytes (Gr. oon, egg + kytos)


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


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


Abnormal gametes


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

Histology 2 muscle and nerve tissuesnikolai.lazarov.pro/files/pharmacy_eng/Muscle...Nerve tissue...

Documents

Transcript of Histology 2 muscle and nerve tissuesnikolai.lazarov.pro/files/pharmacy_eng/Muscle...Nerve tissue...