Female Reproductive System
General Organization
- External reproductive organs
- Vulva
- Labia majora + labia minora
- Clitoris
- Erectile tissue equivalent to
male penis
- Urethral and vaginal opening
- Internal reproductive organs:
- Ovaries = oocyte formation
- Oviducts = transport of oocyte +
fertilisation
- 3 main sections:
- Infundibulum: funnel like
structure, capture oocyte
- Ampulla: proximal part,
fertilisation occurs at ampulla
and isthmus junction (spends
15-18 hours here)
- Isthmus: distal, narrow, contain smooth muscle and ciliated glandular epithelium
to help move embryo to uterus
- Uterus = transport of sperm, implantation, support for fetal development
- Wall consists of 3 layers:
- Endometrium: mucus membrane, highly vascularized, grow and shed during
menstrual cycle
- Myometrium: smooth muscle layers, regulated by ovarian hormones and
oxytocin
- Perimetrium: connective tissue
- Cervix = passage bw uterus and vagina
- Made of fibrous connective tissue with collagen and elastin
- Influenced by estrogen and progesterone
- Possess mucus producing cells to help lubricate
- Vagina = receptacle for male penis
- Highly secretory
- Outer part made of stratified squamous epithelium resistant to mechanical stress
- Resident bacteria on surface secrete lactic acid, increase resistance to infection
, Ovarian and Estrous Cycle
Formation and Activation of primordial follicles
- After initial differentiation of the gonad:
- Large number of oocytes will die
- Squamous granulosa cells start to differentiate
- Oocytes organized in clusters (cysts) surrounded by the squamous granulosa =
primordial follicle
- Cysts break down and oocytes surrounded by a cuboidal granulosa cells = primary
follicle
- Once stimulated into a primary follicle, the process is irreversible
- This process results in significant oocyte death, critical stage
- Oocytes start meiosis and arrest in prophase I, will not complete first division
- Timing differs bw species
- Primordial follicles do not proliferate, population represents a females total reproductive potential
- Process of primordial follicle formation is gonadotropin independent in mammals
- In vivo, a factor must block activation of prophase I
Primary follicle
- Simple cuboidal cells surrounding the oocyte
- Meiosis arrested in diplotene stage of prophase I
- During this arrest, chromosomes decondense and are actively transcribed = tremendous growth of
oocytes
- A membrane is formed surrounding the oocyte = zona pellucida as ZP protein genes are
expressed
- Factors secreted by the oocyte stimulate granulosa cells
- In turn, granulosa cells from primary follicle secrete factors for oocyte
- Oocyte growth
- Replication of cytoplasm organelles especially mitochondria and their DNA
- Increase in ribosome, mRNA and proteins
- Lots of nutrients stored in granules and vesicles
- Golgi apparatus enlarge and moves to the periphery (export ZP proteins)
- Centriole disappears
- Interactions Oocyte - granulosa
- Granulosa cells start expressing FSH receptor and are now responsive to FSH
- FSH maintains arrest through cAMP
- Communication via gap junctions bw granulosa cells and oocytes critical to maintain
arrest
Secondary Follicle
- Large increase in granulosa cells layers, surrounded by a basal lamina
- Theca cells start to multiply on the outside of the basal lamina
- Simultaneously blood vessels develop within the theca
General Organization
- External reproductive organs
- Vulva
- Labia majora + labia minora
- Clitoris
- Erectile tissue equivalent to
male penis
- Urethral and vaginal opening
- Internal reproductive organs:
- Ovaries = oocyte formation
- Oviducts = transport of oocyte +
fertilisation
- 3 main sections:
- Infundibulum: funnel like
structure, capture oocyte
- Ampulla: proximal part,
fertilisation occurs at ampulla
and isthmus junction (spends
15-18 hours here)
- Isthmus: distal, narrow, contain smooth muscle and ciliated glandular epithelium
to help move embryo to uterus
- Uterus = transport of sperm, implantation, support for fetal development
- Wall consists of 3 layers:
- Endometrium: mucus membrane, highly vascularized, grow and shed during
menstrual cycle
- Myometrium: smooth muscle layers, regulated by ovarian hormones and
oxytocin
- Perimetrium: connective tissue
- Cervix = passage bw uterus and vagina
- Made of fibrous connective tissue with collagen and elastin
- Influenced by estrogen and progesterone
- Possess mucus producing cells to help lubricate
- Vagina = receptacle for male penis
- Highly secretory
- Outer part made of stratified squamous epithelium resistant to mechanical stress
- Resident bacteria on surface secrete lactic acid, increase resistance to infection
, Ovarian and Estrous Cycle
Formation and Activation of primordial follicles
- After initial differentiation of the gonad:
- Large number of oocytes will die
- Squamous granulosa cells start to differentiate
- Oocytes organized in clusters (cysts) surrounded by the squamous granulosa =
primordial follicle
- Cysts break down and oocytes surrounded by a cuboidal granulosa cells = primary
follicle
- Once stimulated into a primary follicle, the process is irreversible
- This process results in significant oocyte death, critical stage
- Oocytes start meiosis and arrest in prophase I, will not complete first division
- Timing differs bw species
- Primordial follicles do not proliferate, population represents a females total reproductive potential
- Process of primordial follicle formation is gonadotropin independent in mammals
- In vivo, a factor must block activation of prophase I
Primary follicle
- Simple cuboidal cells surrounding the oocyte
- Meiosis arrested in diplotene stage of prophase I
- During this arrest, chromosomes decondense and are actively transcribed = tremendous growth of
oocytes
- A membrane is formed surrounding the oocyte = zona pellucida as ZP protein genes are
expressed
- Factors secreted by the oocyte stimulate granulosa cells
- In turn, granulosa cells from primary follicle secrete factors for oocyte
- Oocyte growth
- Replication of cytoplasm organelles especially mitochondria and their DNA
- Increase in ribosome, mRNA and proteins
- Lots of nutrients stored in granules and vesicles
- Golgi apparatus enlarge and moves to the periphery (export ZP proteins)
- Centriole disappears
- Interactions Oocyte - granulosa
- Granulosa cells start expressing FSH receptor and are now responsive to FSH
- FSH maintains arrest through cAMP
- Communication via gap junctions bw granulosa cells and oocytes critical to maintain
arrest
Secondary Follicle
- Large increase in granulosa cells layers, surrounded by a basal lamina
- Theca cells start to multiply on the outside of the basal lamina
- Simultaneously blood vessels develop within the theca
