Sexual Reproduction in
Flowering plants
Prefertilisation events: microsporogenesis
In flower the androecium which consists of a whorl of stamens represent the male reproductive organ
and the gynoecium which represents the female reproductive organ differentiate and develop.
As the anther develops, which is generally bilobed structure, the sporogenous tissue cells go through
meiotic divisions leading to formation of microspore tetrads.
As each cell of the sporogenous tissue has the potency to give rise to a microspore tetrad therefore,
each one can be treated as potential pollen or microspore mother cell. The process which involves the
formation of the microspores from a pollen mother cell (PMC) with the help of meiosis is called
microsporogenesis.
PREFERTILISATION EVENTS: MEGASPOROGENESIS
THE PROCESS WHICH INVOLVES THE FORMATION OF MEGASPORES FROM THE
MEGASPORE MOTHER CELL IS CALLED MEGASPOROGENESIS.
IN OVULES, DIFFERENTIATION OF A SINGLE MEGASPORE MOTHER CELL (MMC)
OCCURS, WHICH IS A LARGE CELL CONTAINING DENSE CYTOPLASM AND A
PROMINENT NUCLEUS, IN THE MICROPYLAR REGION OF THE NUCELLUS.
THE MMC UNDERGOES MEIOTIC DIVISION WHICH RESULTS IN THE PRODUCTION OF
FOUR MEGASPORES.
MONOSPORIC DEVELOPMENT
In flowering plants, one of the megaspores is utilized i.e develops into the female gametophyte which is
embryo sac while the other three degenerate that is become non functional.
This method which involves the formation of embryo sac from a single megaspore is termed monosporic
development.
The nucleus of the functional megaspore divides in a mitotic manner where nuclear divisions are not
immediately followed by cell wall formation thus becoming strictly free nuclear, to form two nuclei
which then move towards the opposite poles, forming the 2-nucleate embryo sac.
Two more sequential mitotic nuclear divisions give rise to the 4-nucleate and later the 8-nucleate stages
of the embryo sac.
Flowering plants
Prefertilisation events: microsporogenesis
In flower the androecium which consists of a whorl of stamens represent the male reproductive organ
and the gynoecium which represents the female reproductive organ differentiate and develop.
As the anther develops, which is generally bilobed structure, the sporogenous tissue cells go through
meiotic divisions leading to formation of microspore tetrads.
As each cell of the sporogenous tissue has the potency to give rise to a microspore tetrad therefore,
each one can be treated as potential pollen or microspore mother cell. The process which involves the
formation of the microspores from a pollen mother cell (PMC) with the help of meiosis is called
microsporogenesis.
PREFERTILISATION EVENTS: MEGASPOROGENESIS
THE PROCESS WHICH INVOLVES THE FORMATION OF MEGASPORES FROM THE
MEGASPORE MOTHER CELL IS CALLED MEGASPOROGENESIS.
IN OVULES, DIFFERENTIATION OF A SINGLE MEGASPORE MOTHER CELL (MMC)
OCCURS, WHICH IS A LARGE CELL CONTAINING DENSE CYTOPLASM AND A
PROMINENT NUCLEUS, IN THE MICROPYLAR REGION OF THE NUCELLUS.
THE MMC UNDERGOES MEIOTIC DIVISION WHICH RESULTS IN THE PRODUCTION OF
FOUR MEGASPORES.
MONOSPORIC DEVELOPMENT
In flowering plants, one of the megaspores is utilized i.e develops into the female gametophyte which is
embryo sac while the other three degenerate that is become non functional.
This method which involves the formation of embryo sac from a single megaspore is termed monosporic
development.
The nucleus of the functional megaspore divides in a mitotic manner where nuclear divisions are not
immediately followed by cell wall formation thus becoming strictly free nuclear, to form two nuclei
which then move towards the opposite poles, forming the 2-nucleate embryo sac.
Two more sequential mitotic nuclear divisions give rise to the 4-nucleate and later the 8-nucleate stages
of the embryo sac.
