Microsporogenesis - Sexual Reproduction in Flowering Plants, Biology, Class 12 Video Lecture

hello friends this video on sexual
reproduction in flowering plants part 4
is brought to you by exam for calm no
more fear from exam now let us look at
the mystery inside the answer because
whatever we are going to wedding will be
uninterested in understanding that is
the formation of male gametes that
happens entirely inside the answer so we
have to dig deep deep inside the answer
so answer as I said is a by load
structure that is it is made up of two
loads it is dying thickness what is
dying thickness die means two and
thickness is derived from the word tikka
between means like structures
present in each room so in each row it
has to keep up tikka is nothing but the
cup shaped structure that is what I was
talking about the sacks so in each lobe
it had it has two tikka so that is why
it is fun dyeing
thickness allow me to journal move
separates the sheikah now what separates
the two sac-like structures it is
separated by a groove like structure and
what this present there now there are
four microsporangia which are present
inside the answer now what is
microsporangia now micro means small and
sporangia represents a structure that
produces force and these holes can give
rise to the male gametophyte so
microsporangia or this is the plural and
then singular to squad micro sporangium
so it is the structure that is going to
produce force and these pores a bit
later
give rights to the male gametophyte so
now you might ask it does not mean that
micros Ferengi are the pollen sacks
which we discuss to the previous slide
are doing the same thing when my clothes
for a change that is the initial thing
that is present so if you look at it it
is something like this anther has two
lobes so
this each lobe has to pick up at the
status why this diet with us right now
inside each load you have a structure
but microsporangia and these
microsporangia will give spores which
will form the male gametophyte that is
thus posed a later form the pollen
grains
now these microsporangia later over a
period of time they form the pollen
sacks why are they called pollen sacks
after some technical after some time
they become the sacks which for in the
pod which contain the pollen grains that
is why they are going to pollen sacks
and this is just the top view the way I
am drawing it it is just the top view
but actually it extends longitudinally
throughout the length because you look
at the structure of the stem in length
this is how it looks like so I am just
giving the top view this is the top view
but actually it extends like this
throughout the length it extends
longitudinally then so in each of these
sacks you are going to have the pollen
grains that is why they are got pollen
sacks but basically leaves stuck shaped
structures or these structures which
give rise to the spokes they are called
micro sporangium so now let us try to
understand the structure of micro
sporangium in more detail because this
is now now we are gradually going deeper
where exactly the male gametes are
formed so we will look at the transverse
section of the micro sporangium to have
a better understanding so this is the
cross-section overall cross-section now
if you look at it in more detail so this
cross-section if you magnify it even
more she we find a structure like this
so if you see it even more closely so if
you just put a my girl a magnifying
glass here and if you look at it very
closely you will see that there are four
layers which are present around the
micros for
so these structures are the micro
sporangium at the four corners right and
what are the layers present they are
epidermis and opium middle layers and
tablet um so these are the four layers
which are present and which is evident
so they are in order actually epidermis
is the outermost layer so this is
epidermis next to the epidermis is the
end of t-shirt
so this layer is endo tissue
next is the middle layers so where we
have the middle layers through this
layer is the middle layer and finally
the innermost layer that is the taffeta
so this layer is taffeta
so these are the four layers which
surround the micro sporangium now what
is the purpose of having so many layers
because the micro sporangium is
extremely delicate because the what is
the purpose of the male reproductive
organ to produce male gametes and which
part of the male reproductive organ
produces the male gamete it is the micro
sporangium so it is just understand how
significant it is so it means a lot of
protection so the first three layers
that is epic third term is and
completion and middle layers these three
layers ensures protection they ensure
that the micros variety of is safe
inside so their job is only to protect
it so you have so many ants three layers
just for protection what about the
innermost layer that is taffeta
but it provides the nourishment to the
pollen grains so it is where to provide
nutrition and everything to the pollen
grains because gradually the boiling
rains are going to be formed something
here so the nutrition and everything
comes from them tap it from there and
now what is there inside the micro
sporangium now inside the cyclosporine
two letters at the center of each mic
Varangian we have specialized tissue
quartz autogenous tissue
so this porcellus tissue is present at
the center of them micros strontium -
this is the skoro genus tissue so what
will this Paulo genus to do just now i
was telling in the previous slide that
microsporangia is that part which can
produce force so from there will it
produce force this force will actually
be produced by this poro genus tissue
which is present at the center of the
microsporangia and this tissue is
present at the center of each micro
sporangium everywhere you have this
spore or genus tissue now the question
is how this photo genus tissue gives
rise to the male gamete so that process
we are get to understand so I hope now
you are clear with the structure at
least so here if you see this is again
yet another magnified version of the
four layers so the outermost layer is
the epidermis then the next layer is the
endothelium and then you have the next
layers that is already here so many
layers not necessary it has to be one it
can be more than one also multiple
layers finding it and then inside that
you have the capital that is the
innermost layer and then inside you can
actually see some cells and what are
these cells these cells are nothing but
the micros for mother cells now please
do not get confused in the next slide
that is what we are doing to understand
so for now you want to store this polo
genus tissue now you might ask what
exactly is this ferocious tissue like
any other tissue this tissue is also
made up of cells and the cells are very
compactly arranged and they are all
gorging yourself that the cells are all
of the of uniform kind and the cells of
this tissue that is the sense of the
spore jealous tissues they undergo
mitotic division to form the microspore
mother cell that is interesting right
now we are gradually
trying to understand how the male
gametes are produced so the sportiness
tissue it is made up of cells and those
cells will undergo meiosis that is the
reduction division so it will undergo
meiosis and what will be formed it will
form micros for mother cells so this
will form my crews for Mother's sake
so let us understand that part so that
is now we will talk about my clothes
poor old chilensis
so this is the process where we will see
how micro spores are produced as I said
the micro sporangium job is to produce
spores and the spores produced by mine
closed for engine they are but mine crew
spores
so the process of formation of
microspores is known as my clothes for
genesis and these microscopes with later
form pollen grains so that also d bc so
formation of microspores also as micros
photo Genesis they found formation of
gametes and spawned gametogenesis
similarly formation of micro sporters
microsporum genesis so now let us
understand how the sportiness cells give
rise to microspores okay so these four
genes cells will differentiate to form
new sites a waterview sites
neo sites are nothing but they are the
mother cell someo sites are nothing but
the gamete mother cell so these myocytes
are the gamete under cell now what do we
mean by count mother cell to some other
existence which gives birth to the
babies right so damage for the cell is
this is the cell that will form
Gallants so that is the gamete mother
cell and they have nine sites or neo
sites
important ok now let's try to understand
the ploidy of the sense here
these myocytes then undergo meiosis of
meiosis what are the origin assets these
photos in the cells which we are talking
about they are deployed they are the
different cells but what we want in the
process of my rules for Genesis what
result do we want we want to form my
rose force okay and what is the toidy of
the micros force are they employed or
deployed so these micro suppose I have
blow so basically we want to form
haploid cells from deploying cells so
what kind of the issues you should take
this it should be reduction division and
reduction division is meiosis
so that is the reason my losses take
case now when I also occurred then what
is the design the result is that haploid
micros force art form and this is known
as since for microspores art form that
is why it is 1 micro spoon can intra
means for since 4 of them are 4 so it is
one of my close phone attract these
understanding once again so the story
starts with the spore Eugene will set
where are they located
if those photo sugar cells form the
storage in this tissue which is located
at the center of each micro sporangium
so you have it here here you have this
foolishness tissue which is made up of
us forward unisex so these for launching
the cells are diploid now these cells
will differentiate to form
myocytes we want to look if i
differentiate that it's that means they
are not basically dividing or anything
they're just grouping up together or
they are differentiating for some
specialized cells and those specialized
cells
the gamma mother said that is the real
sense this is legal sites are a game
they are also deployed and these flying
sites will undergo meiosis which is the
induction division and it will form for
applying sets and these four haploid
cells are nothing but the mine crows
force since four of them are gone so at
this point I'm closed for a track so
this is how my crossbows are apart now
what happens to these Michaels force now
with maturity these micro screws will
dissociate from each other
elect a track something like this so we
can look at the figure so this is how a
single stem is and this will undergo
masses and it will give rise to four
sets
so a peg drag will be form so this is
how that they tribe will look like but
again with maturity they will dissociate
to form four separate sets but they will
not give any - together all these so how
they mature they will get dissociated
from each other and then these will
later get enough to form pollen wings
now how that development with pollen
grains table is this right will
understand that so for that you need
don't move about volume wings so I hope
it is clear to you okay so let's go back
so as I said this will dissociate to
form the microspores
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