PHY3181 Lecture Notes - Lecture 2: Blastocoel, Aromatase, Hematocrit
30 Jun 2018
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THEME 2: FEMALE REPRO
Lecture 5: ovarian physiology
Formation of the ovary
• Surface epithelium
• Outer layer = tunica albuginea (made
up of collagen and fibrous tissue)
• Cortex – have primordial follicles
• Follicles
• Medulla – has growing follicles
Oogenesis
• Production of female germ cells
• Primordial germ cells migrate to the
coelomic epithelium of the gonadal
ridge – we are born with around a
million primordialgerm cells at birth
• After embryonic sexual differentiation
primordial germ cells proliferate and
become oogonia by week 20 of
pregnancy approx. 7 million oogonia
present
• Note that follicular genesis and
oogenesis occur parallel to each other
Process before birth
• 2n oogonium undergoes mitosis
• Forms a primary oocyte arrests in
prophase I (2n)
After puberty
• Meiosis continues secondary
oocyte (1n) (arrests in metaphase II)
• Undergoes ovulation – gets extra chrm
from sperm
• Meiosis and fertilisation
• 2n = fertilised egg + 1n polar body
Follicles
• Are the basic unit of female
reproduction
• Roughly spherical circular in shape
• Comprises: oocycte (egg), granulosa
and theca cells
• Develop from primordial follicle to
ovulation by a number of different
stages
• Many different stages can be seen in
an ovary at any one time
The ovary at birth
• Most follicles remain in the resting
stage
• This pool of follicles = ovarian reserve
The ovarian reserve includes:
• Primordial follicles – surrounded by
flattened granulosa
• Transitory follicle – oocyte surrounded
by a mix of flattened and cuboidal
granulosa cells
• Small primary follicle – oocyte
surrounded by a single layer of
cuboidal granulosa cells
At menopause the oocytes are no longer
considered to be viable to be fertilised
Folliculogenesis is the maturation of the
ovarian follicle. The ovarian follicle contains an
immature oocyte plus other somatic cells that
support and nurture the oocyte and produce
hormones. Folliculogenesis describe the
progression of a number of small primordial
follicles into large pre-ovulatory follicles.
Primordial follicle: Contains immature primary
oocyte and only one layer of squamous (flat)
granulosa cells. They are present from birth
and define the ovarian reserve. A pool of
primordial follicles is recruited to start
Document Summary
Formation of the ovary: surface epithelium, outer layer = tunica albuginea (made up of collagen and fibrous tissue, cortex have primordial follicles, follicles, medulla has growing follicles. 7 million oogonia present: note that follicular genesis and oogenesis occur parallel to each other. Process before birth: 2n oogonium undergoes mitosis, forms a primary oocyte arrests in prophase i (2n) After puberty: meiosis continues secondary oocyte (1n) (arrests in metaphase ii, undergoes ovulation gets extra chrm from sperm, meiosis and fertilisation, 2n = fertilised egg + 1n polar body. Follicles: develop from primordial follicle to ovulation by a number of different stages, many different stages can be seen in an ovary at any one time. The ovary at birth: most follicles remain in the resting stage, this pool of follicles = ovarian reserve. At menopause the oocytes are no longer considered to be viable to be fertilised. Folliculogenesis is the maturation of the ovarian follicle.
