Making eggs Flashcards
The oocyte population ____________ steadily after birth
Declines
What are the layers of the oocyte, from center to the exterior?
Oocyte, zona pellucida, granulosa cells, theca cells
Where are theca cells located?
Outside the basement membrane
The primordial follicle consists of the _____________
Oocyte
The primary follicle consists of the oocyte and the ____________ cells
Granulosa
The antral follicle consists of the oocyte, the granulosa cells and the ___________
Antrum
The pre-ovulatory follicle consists of two groups of granulosa cells. What are they?
Mural and cumulus granulosa cells
During which period are LH (luteinizing hormone) and FSH (follicle-stimulating hormone) the highest?
Fertile period
When do primordial follicles enter into growth?
Every month
Where do all the oocytes go?
Oocytes grow and are ovulated
Oocytes begin but do not complete growth and are not ovulated
Oocytes do not grow and are eventually degraded
What is the shape of the primordial granulosa cell?
Squamous
What is the shape of the primary granulosa cell?
Cuboidal
Which cells signal to the oocyte to grow?
Granulosa cells
What initiates the growth by granulosa cells?
Growth factor binds to its receptor (Receptor tyrosine kinase) and leads to signaling pathways that trigger the increase of protein synthesis
How does local relaxation of the ovarian stoma activate primordial follicles?
Dense matrix exerts pressure that flattens cells and prevents them from growing
When pressure is released, granulosa cells become cuboidal and send a signal to the oocyte to grow cells
What is the size of the pre-ovulatory follicle?
100 microns in diameter
How is mRNA synthesized and stored for the growth of oocytes?
mRNA acquires poly-A tail in the nucleus
Message is transcribed and sent out into the cytoplasm for translation
Deadenylation shortens the poly-A tail, the product is not translated and stored
What is the function of CPE in the cytoplasmic deadenylation element?
Determines the silence of the sequence
What is the relation between oocyte diameter and mitochondria?
The larger the oocyte, the more mitochondria will be made
The volume of an oocyte increases ________ fold
100
What is needed for the growth of the oocyte?
Gap junctional communication between oocytes and granulosa cells
What can be transported through the gap junctions?
Small molecules such as amino acids and glucose
The zona pellucida is composed of three or four _______________
Glycoproteins
Filopodia termed transzonal projections (TZPs) extend from the _____________ cells to the oocyte
Granulosa
Thecal cells synthesize testosterone from _____________
Cholesterol
Granulosa cells convert testosterone to _____________
Estradiol
What is the difference between FSH and LH?
They both have different subunits for the beta unit
Where are FSH and LH produced?
Pituitary gland
The final stage of follicular growth occurs during the _______________ cycle and requires ______________
Ovulatory; FSH
FSH is required for the __________ stage of the follicle
Antral
Most pre-antral follicles die owing to insufficient ___________
FSH
What inhibits the production of FSH?
Estrogen produced by growing follicles
Treatments to raise __________ increase the number of ______________ for assisted reproduction
FSH; oocytes
What triggers the first meiotic division in the final stage of oocyte development?
LH
What are the differences in meiosis in males and females?
Males: Meiosis I and II happens during gametogenesis
Females: Meiosis I happens during maturation and meiosis II happens after fertilization, creating two polar bodies
Place these events of meiotic maturation in order:
GVBD, spindle migration, first polar body extrusion, spindle formation, metaphase II arrest
GVBD, spindle formation, spindle migration, first polar body extrusion, metaphase II arrest
What is the role of LH in the oocyte?
LH binds to its receptor on mural granulosa cells and activates signaling pathway
It signals to EGFR ligands which inhibit cGMP to initiate maturation
High cGMP triggers maturation inhibition
What is the mechanism behind cGMP keeping cAMP levels high?
High cGMP -> PDE3A inhibited, high cAMP, active PKA, CDC25B and CDK1/cyclin B1 complex inactive
Low cGMP -> PDE3A activated, low cAMP, PKA inactive, CDC25B active and CDK1/cyclin B1 active
True or false: The fertility of a woman declines with time
True
What is an example of meiotic error related to age-dependent fertility of women?
Trisomy 21
What is the role of cohesins in chromosome segregation?
Cohesins hold the chromosomes together and need to be broken apart by separase for chromosome segregation
What was the experiment to show that cohesins were vital in preventing meiotic disorders?
Remove cumulus-oocyte complex from pre-ovulatory follicle -> inject cohesins into oocyte -> permit meiotic maturation in vitro -> fertilize egg
Which of these is not a key event of cytoplasmic maturation?
a) Redistribution of mRNA
b) Changes in protein synthesis
c) Redistribution of ER
d) Accumulation of cortical granules at the cortex
a)
When does transcriptional activity stop in oocytes?
When the oocytes have matured
When does the repressed mRNA bearing CPE become translationally activated?
When cytoplasmic maturation occurs
