What is Oogenesis?
Oogenesis is the process of formation of female gametes. This process begins
inside the fetus before birth. The steps in oogenesis up to the production of primary
oocytes occur before birth. Primary oocytes do not divide further. They either
become secondary oocytes or degenerate.
Oogenesis occurs in the outermost layers of the ovaries. Oogenesis starts with a
germ cell called oogonium and undergoes mitosis to increase in number.
Oogonia, formed before birth, undergo mitosis to form primary oocytes.
these start to divide by meiosis, but the process stops at prophase 1
Germinal epithelium divides to form the follicle cells which surround
the primary oocytes to form primary follicles.
Primary oocytes do not mature until just before ovulation
At puberty, hormones stimulate the follicles to develop further. Each month
several start, but only one fully develops into graafian follicle.
primary oocyte completes the first meiotic division to form the haploid
secondary oocyte and a small polar body
mature graafian follicle migrates to surface of ovary
where it bursta, releasing the secondary oocyte - ovulation
secondary oocyte begins meiotic division, but this is stopped
at metaphase unless fertilization takes place
on fertilization division completes to form a large ovum and a second polar
body
nucleus of ovum fuses with that of the sperm to form a zygote
after ovulation the graafian follicle becomes the corpus luteum. This breaks
down if fertilization does not take place, but produces hormones during
pregnancy if it does
Oogenesis is the process of formation of female gametes. This process begins
inside the fetus before birth. The steps in oogenesis up to the production of primary
oocytes occur before birth. Primary oocytes do not divide further. They either
become secondary oocytes or degenerate.
Oogenesis occurs in the outermost layers of the ovaries. Oogenesis starts with a
germ cell called oogonium and undergoes mitosis to increase in number.
Oogonia, formed before birth, undergo mitosis to form primary oocytes.
these start to divide by meiosis, but the process stops at prophase 1
Germinal epithelium divides to form the follicle cells which surround
the primary oocytes to form primary follicles.
Primary oocytes do not mature until just before ovulation
At puberty, hormones stimulate the follicles to develop further. Each month
several start, but only one fully develops into graafian follicle.
primary oocyte completes the first meiotic division to form the haploid
secondary oocyte and a small polar body
mature graafian follicle migrates to surface of ovary
where it bursta, releasing the secondary oocyte - ovulation
secondary oocyte begins meiotic division, but this is stopped
at metaphase unless fertilization takes place
on fertilization division completes to form a large ovum and a second polar
body
nucleus of ovum fuses with that of the sperm to form a zygote
after ovulation the graafian follicle becomes the corpus luteum. This breaks
down if fertilization does not take place, but produces hormones during
pregnancy if it does
