21-11-2012, 02:34 PM
OOGENESIS
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Introduction:-
In fact, we the caretakers of volumes of mythological token can’t but agree that the God dropped a pair of male and female chap to his earth at the time of creation of it with his bless or curse this pair abled to produce the vast progenies. Our science remains tight lipped at this impossible absurts but can’t unveil the truth behind the need of this sexual differentiation.
Our science perhaps proceeds from that start, that sexual reproduction is an act of that manner where as two individuals of different sexes have to mate to acquire the desired progeny like them and to acquire the desired progeny like them and to continue the race. In this regard the gametes are the gift to sexual reproduction. In a meticulous manner the gametes are produced in both the sexes, i.e., male and female, then they are lead to unite and their union like a stick to match box ignite a great fire of progeny.
Truly the female sex is the first stage of development of gamete which is conducted by a physiological process referred as oogenesis that is homologous to the process found in male, the Spermatogenesis. The essential process during this phase is the transformation of certain cells in the parent into specialized cells, i.e., the egg or ovum in the female and spermatozoa in the males. In female a cluster of germinal epithelial cells from ovary undergo a series of cytoplasmic and genome level change to give the product of oogenesis, the ovum which later on unite with a sperm to result a zygote.
The germinal epithelium buds off new cells which aggregate in small groups inside the storma. Each group of cells of these follicles grows vigorously and forms the ovum.
Site of Oogenesis: -
Generally oogenesis occurs in the female reproductive organ called Ovary. In case of mammals the ovaries are compact and differentiated into following regions:-
(a) Germinal epithelium: -
It is the outermost covering providing the primordial germ cells for oogenesis.
(b) Storma: -
A germinal epithelium surrounds the connective tissue called storma. Storma is differentiated into outer cortex and inner medulla. Developing ovum is found in the cortex of ovary.
Process of Oogenesis: -
Although it is a similar process to that of spermatogenesis but in certain aspects it is very much diverse from the later. It is a complicated process as producing ova which are very larger than any other somatic cells due to deposition of reserve food material. This complicated process is hence divisible into three phases accounting many cytological changes:-
(a) Phase of multiplication
(b) Growth phase
© Maturation phase