muscle, nerve and reproductive tissues - lazarovnikolai.lazarov.pro/lectures/2014/pharmacy/03... ·...

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:NB:NB:NB: muscles can only pull or contract, not pushmuscles can only pull or contract, not pushmuscles can only pull or contract, not pushmuscles 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 mortisSliding 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 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


� 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� lypofuscin 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 grid�mitochondria� 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” synapse�synaptic glomeruli


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• α- and β-adrenergic receptors• receptors for Glu, SER, GABA, neuropeptides

� tyrosine kinases receptor family� guanylate cyclase receptors� cytokine receptors

� autoreceptors

� Acetylcholinesterase (AChE)


Arvid CarlssonArvid CarlssonArvid CarlssonArvid Carlsson, Paul GreengardPaul GreengardPaul GreengardPaul Greengard andandandand Eric Kandel Eric Kandel Eric Kandel Eric Kandel for their discoveries for their discoveries for their discoveries for their discoveries concerning "signal transduction in the nervous system"concerning "signal transduction in the nervous system"concerning "signal transduction in the nervous system"concerning "signal transduction in the nervous system"

ArvidArvidArvidArvid CarlssonCarlssonCarlssonCarlsson, 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.

PaulPaulPaulPaul GreengardGreengardGreengardGreengard, 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.

EricEricEricEric KandelKandelKandelKandel, 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 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)


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. Sherrington1857–1952

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 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


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


� 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 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…

muscle, nerve and reproductive tissues - lazarovnikolai.lazarov.pro/lectures/2014/pharmacy/03... ·...

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