Ovarian and Menstrual Cycles Flashcards
When does meiosis begin?
Week 8-9
In what phase is primary oocyte arrested in until ovulation?
Prophase I of meiosis I
At about 20 weeks gestation, there’s about 20 million oocyte, but that number significant decreases to _ by puberty.
about 400,000
In what phase is secondary oocyte arrested in until fertilization?
metaphase II of meiosis II
what are the function of ovaries?
- produce female gamates
- secrete estrogen and progesterone (maintains the uterus)
- regulate postnatal growth
- control development of secondary sex characteristics
Where on the ovary are the oocyte containing the follicles located?
Cortex
what makes up the medulla of the ovary?
stroma and blood supply
What are the three phases of the ovarian cycle?
- Follicular (days 1-14)
- Ovulation
- Luteal (days 15-28)
What happens during the follicular phase?
- growth of the dominant follicle
- primordial to tertiary (graffian) follicle
How does does the follicular phase typically last?
10-14 days
What happens during the ovulation phase of the ovarian cycle?
- oocyte ruptures out of the graafian follicle
- occurs mid-cycle at Day 14
- in reponse to surge to LH
what happens during the luteal phase of the ovarian cycle?
-corpus luteum forms, secretes progesterone and estrogen to accomodate potential gestation.
How long does the luteal phase usually last?
14 days
List what changes (names given to the follicle) follicle undergoes in the follicular phase of the ovarian cycle
- Primordial follicle
- Early primary or unilayered follicle
- Late primary or multilayered follicle
- Secondary follicle
- Mature Graffian follicle
In the primordial follicle, what surrounds the primary oocyte and what time period of life is this most prevalent in?
In the primoridal follicle, primary oocyte is surrounded by squamous epithelium. This is before puberty; and this follicle is inactive
What happens during the early primary or unilayered follicle phase of the follicular phase?
- Single layer of cuboidal follicular epithelium;
- ZP begins to form.
What happens during the late primary (multilayered follicle) phase of the follicular phase?
- Several layers of cuboidal follicular epithelial cells.
- ZP forms glycoprotein coat around the oocyte
What changes take place during the secondary follicle phase of the follicular phase?
- Follicular cells continue to proliferate and forms the stratum (zona) granulosum
- Ovarian stroma around the follicle differentiates into: theca interna and theca externa
- Fluid-filled cavities (Call-exner bodies) appear between follicular cells (fluid is liquor folliculi)
- Antrum beings to form
What are theca interna cells?
Squamous cells surrounding follicular cells
What are theca externa?
Capsule-like layer continuous with the connective tissue of the ovary
During the secondary follicular phase of the follicular phase, the oocyte is in what phase? (primary, secondary, tertiary)
Still a primary oocyte.
Describe the changes that take place as the follicle becomes a mature graffian follicle.
- Antrum occupies much of the space
- Oocyte displaced to one side
- Develop corona radiata
what is corona radiata and during what phase are you likely to see its development?
Corona radiata is layer of follicular cells surrounding oocyte developed during the mature graffian follicle phase.
What is cumulus oophorus and when does it develop?
Cumulus oophorus is a pedestal of folliclular cells anchoring oocyte to the wall; develops during mature graafian follicle
True or false: a graafian follcle is a tertiary follicle
False It’s still a secondary follicle but with some added changes.
During ovulation, what two layers accompanies the oocyte as it shot out of the follicle?
zona pellucida and the corona radiata
what are the two forms of paracrine signaling that takes place during folliculogenesis?
- Granulosa cell-primary oocyte bidirectional signaling
2. theca cell-granulosa cell synergistic communication
Members of which superfamily feature is prominently amongst the growing list of extracellular ligands implicated in the bi-directional communication during foliculogenesis?
TGF-beta
Which growth factor and transcriptional factor are needed during the bidirectional signaling during folliculogenesis?
GDF-9 and BMP-15
What hormones are required during the bidirectional signaling of folliculogenesis?
AMH, Activin, inhibin
What is polycystic ovarian syndrome (PCOS)?
Enlarged ovaries with multiple cysts which results from disrupted folliculogenesis caused by a defect in the paracrine oocyte-granulosa cell signaling mechanism specially related to AMH.
what are some clinical features of polycystic ovarian syndrome?
Infrequent or prolonged menstrual periods, excess hair growth, acne, and obesity.
-In adolescents, infrequent or absent menstruation may raise suspicion for the condition
Ovulation is stimulated by _
LH surge
During ovulation, Follicular cells begin to develop receptors for what hormone?
LH