Histology of Follicular Development Flashcards
2 main supporting mesenteries of the ovary
Mesovarium Mesosalpinx (of broad ligament)
What structure is responsible for:
- production of female gametes
- secretion of estrogen and progesterones
- regulation of postnatal growth of repro organs
- dev’t of secondary sex characteristics
Ovary
Each ovary is lined by an ovarian surface epithelium = ____ _____ epithelium with a peripheral dense CT called the ____ ______
Simple squamous-to-low cuboidal; tunica albuginea
Each ovary has a peripheral cortex with a deep medulla.
In which layer would you find CT, interstitial cells, neurovasculature, and lymphatics?
Medulla
Each ovary has a peripheral cortex with a deep medulla.
In which layer would you find CT and follicles with primary oocytes? At what stage of meiosis are these oocytes?
Cortex; follicles with primary oocytes that are arrested at prophase I
The ovarian surface epithelium (OSE) will form ______ cells and ______ cells which comprise the growing follicles after birth
Granulosa; stromal
3 phases of the ovarian cycle
- Follicular
- Ovulatory
- Luteal
The follicular phase of the ovarian cycle involves the sequential dev’t of several primordial follicles. What are the 5 stages of the follicle as it develops?
- Primary (unilayered) follicle
- Secondary (multilayered) follicle
- Pre-antral follicle
- Antral follicle
- Preovulatory follicle (graafian follicle)
The relative proportions of the follicles are not maintained; mature follicles are much _____ relative to early follicles
Larger
A follicle consists of a large, groing oocyte w/a large nucleus and prominent nucleolus. _______ cells surround the oocyte and support its rapid growth
Follicular
Cells that have begin 1st meiotic division, arrested at prophase 1
Primary oocyte
Single layer of cells that surround a primordial follicle, associated with a basement membrane
Follicular cells
Follicular cells that proliferate and become stratified
Granulosa cells
Granulosa cells will eventually segregate into what 3 cell groups?
Cumulus oophorus
Mural granulosa cells
Corona radiata
Coat of glycoproteins that encases primary oocyte, involved with sperm recognition
Zona pellucida
Ovarian stromal cells differentiate and form an outer covering surrounding the follicle, consisting of 2 layers. The _____ _____ is steroid-producing, while the _____ _____ consists of fibroblasts and smooth muscle
Theca interna; theca externa
Cells that complete the 1st meiotic division (with LH stimulation), enter meiosis II but arrest at metaphase II
Secondary oocytes
______ follicles are numerous throughout the cortex, are about 25 micrometers in diameter and surrouded by a simple squamous layer of granulosa cells
Primordial
_____ cells are recruited to the primordial follicles to initiate folliculogenesis
Granulosa
Primordial follicles that progress to primary follicles do so when the single layer of squamous granulosa cells becomes a _____ _____ layer of granulosa cells
Simple cuboidal
What separates the granulosa cells from the stroma of the ovary?
Basal lamina
When the ____ ____ begins to assemble, it separates the primary oocyte fom the granulosa cells
Zona pellucida
When primary follicles begin to develop into secondary follicles, the granulosa cells proliferate into a ____ ____ epithelium and the ____ begins to organize
Stratified cuboidal; theca
The ______ is a vascularized cell layer adjacent to the basal lamina supporting the granulosa cells
The _____ is a fibrous cellular layer continuous with the ovarian stroma
Theca interna
Theca externa
With _____ follicles, small intercellular spaces called ______ develop among the granulosa cells
These spaces contain _______ derived from blood vessels of the theca interna, which reaches the antrum by an osmotic gradient
Preantral; call-exner bodies
Follicular fluid
Secondary follicle —> preantral follicle can by a close transition, typically determined by the presence of what histological finding?
Call-Exner bodies
In the antral follicle, call-exner bodies formed in the preantral follicle will coalesce into the ________
Antrum
What is the function of granulosa cells surrounding the antral follicle?
Actively synthesize and secrete estrogen
Produce follicular fluid
The ______ follicle is when the antrum has reached its maximum size, and fluid segregates the granulosa cells
Preovulatory
In the preovulatory follicle, fluid segregates the granulosa cells into:
_______ _____ = anchors the primary oocyte to follicle, nutrient delivery channel
__________ = line wall of follicle
________ = granulosa cells anchored to ZP
Cumulus oophorous
Mural granulosa cells
Corona radiata
Describe the theca interna vs. theca externa in the preovulatory follicle
Theca interna = well-vascularized, elongated cells w/lipid droplets
Theca externa = formed a CT, capsule-like layer, continuous with the ovarian stroma
During the ovulatory phase, the mature preovulatory follicle protrudes from the ovarian surface, forming a _________. Proteolytic activity of the theca externa and _______ causes rupture
Stigma; tunica albuginea
What happens to the gamete released during the ovulatory phase in terms of cellular development?
Completes meiosis I and becomes secondary oocyte (due to LH surge), but still needs to finish meiosis II
It then enters the oviduct
What cells/cell components repair the ovarian surface epithelium following follicle rupture?
Mural granulosa cells and theca interna
After ovulation during the luteal phase, the residual mural granulosa cell layer folds and becomes part of the ________
Corpus luteum
During the luteal phase in a process called luteinization the following events occur:
- Breakdown of the follicle ______
- Blood vessel invasion of empty antrum, blood flows into the antral space and coagulates, forming a __________
- Mural granulosa cells become _________ cells
- Theca interna cells become ________ cells
Basal lamina
Corpus hemorrhagicum
Granulosa lutein
Theca lutein
Function of the corpus luteum is regulated by what 2 gonadotropins?
LH
FSH
FSH stimulates the production of ____ and _______ from the granulosa lutein cells
LH stimulates the production of _____ and _____ by theca lutein cells. The latter is translocated into the granulosa lutein cells for aromatization into _____
Progesterone; estradiol
Progesterone; androstenedione; estradiol
During pregnancy, ____ and _____ upregulate the effects of estradiol produced by granulosa lutein cells by enhancing the production of estrogen receptors
Estradiol stimulates granulosa lutein cells to take up _____ from blood, which is then stored in lipid droplets and transported to mitochondria for further progesterone synthesis
Prolactin; placental lactogens
Cholesterol
If fertilization does not occur, the corpus luteum undergoes a process of regression called _______, involving a programmed cell death (apoptosis). It is triggered by endometrial __________
It involves reduction in blood flow, T cell production of IFN-y, and macrophage production of TNF ligand
Luteolysis; prostaglandin F2a
The corpus luteum promotes endometrial changes that support implantation.
_________ cells have a hypertrophic, steroid-secreting appearance. They secrete progesterone and estrogen with FSH and LH stimulation, and will themselves express LH receptors as an essential step for luteinization
______ cells produce androstenedione and progesterone with LH stimulation
Granulosa lutein
Theca lutein
What happens to the corpus luteum during the luteal phase if fertilization DOES occur?
Corpus luteum continues to enlarge and produce progesterone and estrogen, under the stimulatory action of hCG from the trophoblast layer
What happens to the corpus luteum during the luteal phase if fertilization DOES NOT occur?
Corpus luteum begins involution stage ~14 days after ovulation
Luteolysis, regression of CL, leads to formation of corpus albicans
Stromal CT replaces degenerating luteal cells
_____ _____ is made up of a scar of CT that forms at the site of the corpus luteum after involution
It is mostly collagen (type I) with a few fibroblasts of other cells and eventually becomes very small
Corpus ablicans
T/F: involution of the corpus luteum typically involves atresia
FALSE - involution of the corpus luteum does not involve atresia, it is mediated by macrophages
About 7 million primary oocytes exist in the ______ ovary
Approximately 400,000 oocytes remain at ______
Only 400 follicles will ovulate monthly beginning at ______
The remaining follicles degenerate and form ______ follicles
Fetal
Birth
Puberty
Atretic
______ = failure of a follicle to ovulate; occurs in the fetal ovary, after birth, and at any stage of development
Atresia
What is the purpose of follicular atresia?
Ensures that only viable follicles, containing oocytes of optimal quality for fertilization, are available
______ is the primary mechanism for follicular atresia, ensuring regression of the follicle without causing an inflammatory response
Apoptosis
During apoptosis process of follicular atresia, a ______ membrane is formed which is thick, folded, basement membrane material
A folded _____ _____ and apoptotic fragmented oocyte can also be seen
Glassy
Zona pellucida
In the absence of fertilization, the CL undergoes involution and regression (proteolysis). Luteal cells are phagocytized by _____ and the former corpus luteum becomes the corpus albicans
Macrophages
During the luteal phase, the antral cavity fills with blood/cell debris, becoming the _________ which is removed by ________
Corpus hemorrhagicum; macrophages
When the antral cavity fills with blood/cell debris, the _______ cells collapse into antral cavity, which is filled with cholesterol esters, theca, blood vessels, WBCs
Granulosa lutein
Granulosa lutein cells are often _____in color d/t carotenoid pigment, lutein
Yellow
The corpus luteum becomes the corpus albicans if fertilization does not occur; if fertilization does occur, _______ will rescue the corpus luteum so that it remains viable for duration of pregnancy, which is similar in structure to LH
hCG
During pregnancy, the corpus luteum produces increasing progesterone — what is its primary function?
Transforms uterine lining into adhesive and supportive structure important for implantation and early pregnancy
There is a transient decrease in _____ following LH surge, which rebounds and peaks midluteal phase.
Progesterone and estrogen reduce LH to basal levels; ______ compensates for this decline
Estrogen
hCG
Lutein cells secrete _____ which suppresses FSH in pregnancy, this is so that additional follicles are not produced in pregnancy
Inhibin A
_______ = demise of an ovarian follicle; predominant process in the ovary that can occur at any time during development
Follicular atresia
During atresia, the ______ and ______ undergo apoptosis, however ______ cells persist and repopulate the cellular stroma of the ovary
Granulosa cells; oocytes; thecal
Thecal cells retain LH receptors and the ability to produce ______; collectively they are referred to as the _______ gland of the ovary
Androgens; interstitial