It is a critical interface between the epidermis and dermis and is a highly specialized structure that allows for communication between different cell types. Examination of BMZ/Structure of BMZ/Origin of BMZ/Function of BMZ/Examples of Some diseases affecting BMZ

3. OVERVIEW
* Examination of BMZ
* Structure of BMZ
* Origin of BMZ
* Function of BMZ
* Examples of Some diseases affecting BMZ

4. ???????
* Basement Membrane
* Dermo – Epidermal Junction (DEJ)
* Basal lamina
* Basement Membrane Zone (BMZ)

6. THE BASEMENT MEMBRANE ZONE
* It is a critical interface between the epidermis and
dermis and is a highly specialized structure that
allows for communication between different cell
types.

9. PAS-positive basement membrane.

10. EXAMINATION OF BMZ
* Relatively poorly demonstrated with eosin in H and E
preparations.

11. * As all basement membranes, it stains strongly for
Glycoproteins and mucopolysaccharides by Periodic
acid schiff stain (PAS).
* It is also stained intensely with silver techniques.

12. * The complexity & heterogeneity of BMZ can be
appreciated only at ELECTRON MICROSCOPIC
level.

16. The basement membrane zone (BMZ) integrates the epidermis
with the underlying dermis. On electron microscopy, the BMZ
has three layers: a central electron-dense region known as the
lamina densa and two regions of lower electron density to
either side of this central region.

17. Ultrastructure of basement membrane (×37,800).
(1, hemidesmosome; 2, lamina lucida; 3, lamina densa; 4,
sublamina densa; 5, melanin; 6, tonofilaments)

21. BMZ
KIF/Hemidesmosome complex
(Basal keratinocyte)
Lamina lucida
Lamina densa
Sub lamina densa

30. KERATIN INTERMEDIATE
FILAMENTS
* Also called tonofilaments, it is comprising keratin
5&14.
* It is a fine filamentous structures maintain the
intracellular architecture & organization of basal cells.
* They course through the basal cells & inserted into
the desmosome & hemidesmosome.

32. ATOMIC MASS UNIT
* The unified atomic mass unit (symbol: u) or dalton
(symbol: Da) is the standard unit that is used for
indicating mass on an atomic or molecular scale
(atomic mass).

33. * One dalton is approximately the mass of one nucleon
(either a single proton or neutron)
= 1.660538921(73)×10−27 kg.

38. HEMIDESMOSOMES (HD)
* Numerous electron-dense plates located in the lower
region of the plasma membrane of the basal cells.

39. * It is closely resembling ½ of the desmosome seen in
cell–cell junction but based on chemical criteria, these
2 structures appear to be immunologically distinctive.

40. * Characteristics of HD proteins has been aided by the
use of auto-antibodies presented in serum samples of
patients with bullous pemphigoid.
* As result of this, the antigens recognized by these
sera identified proteins ranging in mass from 165-
240 kDa.
* These proteins are immunologically & structurally
distinct.

41. * Monoclonal antibodies have been constructed to both
intracellular & extracellular regions of HD.

46. BPAG1
* It is a homodimer with homology to desmosomal
desmoplakin.
* It is generally believed that it is the major component
of the HD inner dense plaque.

50. PLECTIN
* It is another dimeric desmoplakin homologue.
* Its tissue distribution is not limited to BMZ.

55. 6 4 INTEGRIN
* They are large class of trans-membrane extra-
cellular matrix binding proteins that provide cell
attachment & subsequent signal transduction.
* It has a selective high affinity for laminin 5.

59. TYPE XVII COLLAGEN (BPAG2)
* 180 kDa
* It is an unusual trans-membrane prt.
Collagenous extra-cellular
domain interact
with laminin 5
Intra-cellular domain
interact mainly
with BPAG1

67. LAMINA LUCIDA (LL)
* External to the plasma membrane
* 25-50 nm in width.
* Contains the anchoring filaments.

68. ANCHORING FILAMENTS
* Series of filaments traversing the lamina lucida from
the epidermal basal cells & insert into the lamina
densa.
* Several antigens forming anchoring filament proteins.

76. LAMININS
* Immunolocalized to basal lamina (= LL+LD).
* Numerous glycoprotein family with semirigid &
extended structures.

77. * It is hetrotrimetric molecule, where each laminin
isoform consisting of
alpha chain.
Beta chain.
Gamma chain.

78. * The 4 extremities of the crosslike structure contain
globular domains, the 3 short arms contain extra
domain, approximately 20 nm from their free end.

79. LAMININ 5
* Its general structure as laminin family.
* It has short arms comparing to other laminins.

80. * Its shape is consistent with its potential to be the
anchoring filament protein.
* It has a high affinity for integrins.
* It also bind to the NC-1 domain of type VII collagen
(the anchoring fibril protein).

93. LAMINA DENSA (LD)
* Appears as an electron-dense amorphous structure.
* 20-50 nm in width.
* At high magnification, it has a granular fibrous
appearance.
* Account for 40-65% of total basement membrane
proteins.

94. * Major proteins component is type IV collagen where it
appears as a filament of variable thickness which is
morphologically distinct from the collagen fibers in the
subjacent dermis.

95. TYPE IV COLLAGEN
* Immunolocalized mainly to LD & also found in
anchoring plaque.
* It has a structure closely related to the intracellular
or procollagen form, typical of all members of the
collagen protein family.

96. * The triple helical nature of the amino terminus of
type IV collagen is unique & has been designated as
the 7-S domain.
* Covalent interactions among 7-S domain of the type
IV collagen are the basis for the specialized fiber
form characteristic of basement membrane.

101. NIDOGEN
* It is a glycoprotein with dumbbell configuration
localized to the LD.
* It is attached to one of the short arms of laminin at
the gamma 1 chain forming a stable complex.
* Nidogen alone as well as laminin- nidogen complex
specifically bind to type IV collagen.

106. PERLECAN
* It is a Heparan sulfate proteoglycan.
* It consists of a core protein of various length with
different numbers of covalently associated
glycosaminoglycan chains.

107. * High sulfate content makes this molecule with highly
negative charge & hydrophilic.
* It swell with hydration & have a major role in
determining which proteins or ions can transverse the
lamina lucida & access the epidermal intracellular
spaces.

119. SUB LAMINA DENSA
* It’s major component is anchoring fibrils which appear
as condensed fibrous aggregates of type VII
collagen.

120. ANCHORING FIBRILS
* Type VII collagen appears to have a major triple-
helical domain is approximately 450 nm in length.

121. * Type VII collagen is synthesized & secreted as
monomeric protein but rapidly dimerizes at the amino
terminals.
* These structures are proteolytically cleaved after
formation of the centrosymmetric dimer.
* The dimers then aggregates laterally to form the
anchoring fibrils.

122. * The complex NC-1 domain binds to laminin 5 & also to
components of the lamina densa.

123. * Many of the anchoring fibrils inserted their distal
ends into electron-dense amorphous-appearing
structures completely independent of lamina densa,
known anchoring plaques.

124. ANCHORING PLAQUES
* The anchoring plaques are electron-dense structure
composed of type IV collagen & laminin.
* They are independent of lamina densa , & distributed
randomly in the papillary dermis below lamina densa &
are inter-related by additional anchoring filaments.

150. REFERENCES
* Adel A. Al-Ghamdi Dermatology Department King
Fahd Hospital of university (Presentation).
* The Basement Membrane Zone- Making the
Connection Vidal MD, AAD.
* Google images.

151. THANK YOU