Histology
➢ Study oftissue
➢ Fundamental aim: Structural
organization of tissues in
organs
4.
Tissue
➢ Group ofsimilar or dissimilar cells
➢ Common origin, similar structure
and common method of
development
➢ Basic division of labour
5.
Types of planttissues
a. Dermal Tissue: Outermost
protective layer of the plant
Based on position and function:
b. Ground Tissue: Mainly
responsible for storage,
photosynthesis, and support
6.
Types of planttissues
Based on position and function:
c. Vascular Tissue: Responsible
for transporting water,
nutrients, and sugars
throughout the plant
7.
Types of planttissues
a. Meristematic tissues
Based on capacity of cell
division:
Two types:
b. Permanent
tissues
8.
Meristem
➢ Group ofsimilar cells with
power of active cell division
➢ Found in:
▪ Apex of root , stem branches
and buds
9.
Meristem
Characteristics features:
➢ Powerof cell division
➢ Small and Undifferentiated Cells
➢ Isometric, oval, rounded or
polygonal in shape
➢ No intercellular spaces
➢ Central vacuole: absent except in
cambial cell and secondary
meristem
10.
Meristem
Characteristics features:
➢ Densecytoplasm and single distinct
central nucleus
➢ High rate of metabolism and respiration
➢ Rapid Growth and Regeneration
➢ Colourless proplastid (Eoplast) instead
of chloroplast
12.
Mass meristem
➢ Cellsdivide in all planes and
increase the volume of plant
➢ Responsible for the early
growth of embryo, sporangia,
endosperm
13.
Plate meristem
➢ Cellsdivide into two planes
➢ Increase the area of plant
parts
➢ Generally help in the
formation of flat structures
like leaf lamina, endodermis
etc.
14.
Rib meristem
➢ Celldivides anticlinically in
single plane only
➢ Responsible for formation of
lateral roots, formation of pith
and cortex in young stem
15.
Meristem types basedon origin
Promeristem
➢ The first formed meristem
➢ Also called the embryonic
meristem
➢ Short-lived and gives rise to
the primary meristem
16.
Meristem types basedon origin
Primary meristem
➢ Derived from embryo
➢ Initiated at opposite poles of the
plant embryo
17.
Meristem types basedon origin
➢ The protoderm: forms the
epidermis;
➢ The ground meristem: forms
ground tissues comprising
parenchyma, collenchyma, and
sclerenchyma cells;
➢ The procambium: forms vascular
tissues (xylem and phloem)
Primary meristem
18.
Meristem types basedon origin
➢ Dermatogen: forms the epidermis;
➢ Peribleme: forms ground tissues
comprising cortex and endodermis
➢ Plerome: forms stelar tissues
(Pericycle, vascular bundle,
medullary rays and pith)
Primary meristem
19.
Apical meristem
➢ Presentin growing points (apices of
root and shoot) of the plant
➢ RAM (root apical meristem) gives rise
to root cap
➢ typically small and nearly spherical
cells
➢ Helps to increase the height
21.
Intercalary meristem
➢ Locatedat the internodes or the
base of the leaves
➢ Help in increasing the length of
the internode
➢ usually seen in
monocotyledonous plants
22.
Lateral meristem
➢ Locatedlaterally
➢ Embedded with permanent tissues
➢ Helps to increase the girth and
diameter
➢ Cork cambium of roots and stems
* Lateral meristem is mostly nominated as
secondary meristem. Sometimes, the two
terms are used interchangeably since both
of them are concerned with increase in
thickness rather than in length (as
in primary meristem).
23.
Lateral meristem
➢ Locatedlaterally
➢ Embedded with permanent
tissues
➢ Helps to increase the girth
and diameter
➢ Cork cambium of roots and
stems
24.
Secondary meristem
➢ Comprisedof undifferentiated (or
partially differentiated), actively
dividing cells
➢ derived from the permanent tissue
➢ Responsible for the secondary growth
in plants, i.e. growth in girth or
thickness
25.
Secondary meristem
➢ Responsiblefor the
secondary growth in plants,
i.e. growth in girth or
thickness
e.g.
➢ vascular cambium of dicot
root
➢ Cork cambium of dicot stem
