Histology Of The Ovarian Follicle Flashcards
Describe the two cycles of the menstrual cycle
Ovarian cycle: ovarian follicles housing primary oocyte undergo folliculogenesis in preparation for ovulation
Uterine cycle: endometrium prepares for implanatation; no fertilization endometrium is shed and menstruation occurs
Functions of the ovary
What are the two supporting mesenteries of the ovary?
Production of female gametes
Secretion of estrogens and progesterone
Regulate postnatal growth of reproductive organs
Development of secondary sexual characteristics
Mesovarium and mesosalpinx of the broad L
Each ovary is lined by an _____.
What is contained in the cortex and medulla?
What does the OSE form>
Ovarian surface epithelium (OSE): simple squamous to low cuboidal; dense CT layer called tunica albuginea
Cortex: CT, follicles with primary oocytes
Medulla: CT, interstitial cells, neurovasculature, lymphatics via hilum
Form granulosa cells and stromal cells -> comprise the growing follicles after birth
Stages of folliculogenesis
Follicular phase
Ovulatory phase
Lateral phase
What are the stages of the development of primordial follicles in the follicular phase?
Primordial follicles Primary (unilayered) follicle Secondary (multilayered) follicle Preantral follicle Antral follicle Preovulatory follicle (graffian follicle)
Cells that have begun 1st meiosis division, arrested a prophase I
Single layer of cells that surround a primordial follicle, associated with basement membrane
Follicular cells that proliferate and become stratified; will eventually segregate into cumulus oophorous, mural granulosa cells, corona radiata
Coat of glycoproteins that encases the primary oocyte, involved in sperm recognition
Ovarian stromal cells differentiate and form the outer covering of the follicle; steroid producing part; other contains fibroblasts and smooth m
Cells that complete 1st meiotic division (with LH stimulation), enter meiosis II, but arrest at metaphase II
Primary oocyte
Follicular cells
Granulosa cells
Zona pellucida:
Theca interna; theca externa
Secondary oocyte
Where are primordial follicles and what surrounds them?
Why are granulosa cells recruited?
What are primary follicles?
What does the basal lamina do?
What begins to assemble?
Numerous in cortex; surrounded by simple squamous layer of granulosa cells
Recruited to initiate folliculogenesis
Primordial follicles -> primary follicles when single layer of squamous granulosa cells becomes simple cuboidal layer of granulosa cells (due to FSH)
Basal lamina separates the granulosa cells from the stroma of the ovary
Zona pellucida; separates primary oocyte from granulosa cells
What makes a secondary follicles?
What begins to organize?
What is the different between theca interna and externa?
Granulosa cells proliferate into stratified cuboidal epithelium
Theca layer
Theca interna: vascularized cell layer adjacent to basal lamina supporting granulosa; contains lipid droplets; produces androstenedione
Theca externa: fibrous cellular layer continuous with ovarian stroma
What are preantral follicles?
What is contained in the spaces?
Small intercellular spaces (Call-Exner bodies) develop among granulosa cells
Spaces contain follicular fluid derived from blood vessels of the theca interna, reach the antrum by osmotic gradient
What is the antral follicle?
What is the function of the granulosa cells?
Call-exner bodies coalesce into the antrum
Actively synthesize and secrete estrogen; produce follicular fluid
What is the preovulatory follicle?
What does the fluid segregate the granulosa cell into and what is their fx?
Antrum reaches its maximum size
Cumulus oophorous: anchor primary oocyte to follicle, nutrient delivery channel
Mural granulosa cells: line the wall of the follicle
Corona radiata: granulosa cells anchored to the zona pellucida; connect through gap junctions to maintain communication
What happens in the ovulatory phase?
Proteolytic activity of the ____ and _____ causes rupture of the follicle.
What hormone causes this rupture?
What repairs the OSE damage following the follicle rupture?
Mature preovulatory follicle protrudes from ovarian surface, forming stigma
Theca externa and tunica albuginea
Surge of LH
Mural granulosa cells and the theca interna
What does the released gamete from the oocyte do after it ruptures?
Completes meiosis I -> becomes secondary oocyte (LH surge)
Needs to finish meiosis II
Enters oviduct
What happens in the luteal phase?
What do the residual mural granulosa cell layer folds become?
What do the theca interna cells become?
After ovulation, their residual mural granulosa cell layer folds become corpus luteum.
Breakdown of follicle basal lamina
Blood vessels invade empty antrum, blood flows into antral space and coagulates forming corpus hemorrhagicum
Mural granulosa cells -> granulosa lutein
Theca interna cells -> theca lutein cells
What are granulosa lutein cells?
What do they produce?
What do theca lutein cells produce?
Hypertrophic, steroid secreting appearance
Secrete progesterone and estrogen with FSH and LH stimulation
Will express LH receptors, essential for luteinization (making the corpus luteum)
Theca lutein cells: produce androstenedione and progesterone with LH stimulation
