Female Reproductive histology Flashcards
what are the two co exisiting events during the menstrual cycle?
Ovarian cycle: several ovarian follicles undergo folliculogenesis in preparation for ovulation
Uterine cycle: concurrent cycle, where the endometrium prepares for implantation
Characteristics of the ovary
Lined by ovarian surface epithelium (OSE)
- simple cuboidal epithelium, embryonic source of granulosa cells and stroma cells comprise the growing follicles
- overlying layer of dense connective tissue capsule called the tunica albuginea
Cortex: CT and ovarian follicles
Medulla: CT, intersitial cells, neurovasculature, lymphatics via the hilum
what are the three main cell types found in the ovary?
Mullerian epithelium: epithelial cells originate from the outer epithelial lining
Germ cells: precursor cells of gametes
Sex cord stromal cells: derived from the stromal component of the ovary (granulosa cells, thecal cells, and fibrocytes)
Characteristics of a follicle?
located in the cortical stroma
contain a single oocyte
Follicular/granulosa cells surround the oocyte to support its growth
early stages of oogenesis occur during fetal life
Ocytes present at birth but remain arrested in meiosis I
what are the three phases of folliculogenesis?
Follicular stage
Ovulatory stage
Luteal phase
what is the difference between a primary oocyte and a secondary oocyte?
Primary oocyte: cells that begun 1st meiotic division and are arrested at prophase I
Secondary oocytes: cells tjat complete 1st meiotic division with LH stimulation and enter meiosis II but arrest at metaphase II
what makes up the zona pellucida? and the ovarian stromal cells
coat of glycoproteins that encases the primary oocyte, involved with sperm recognition
Ovarian stromal cells differentiate and form outer coverings that surround the follicle
- Theca interna: steroid producing
- Theca externa: fibroblasts and smooth muscle
Characteristics of the primordial follicles
numerous throughout the cortex
about 25 um in diameter and surrounded by simple squamous layer of folicular/pregranulosa cells
characteristics of the primary follicles
Primordial follicles become primary follicles when single layer of squamous granulosa cells turn to simple cuboidal layer of granulosa cells
basal lamina separates the granulosa cells from the stroma of the ovary
Zona pellucida will begin to assemble, separates primary oocyte from granulosa cells
Characteristics of a late primary follicle
Follicuar cells continue to proliferate
forming a stratified cuboidal follicular epithelium made of granulosa cells
-these cells will communicate via gap junctions
Follicle is still avascular and surrounded by a basement membrane
characteristics of a Secondary follicle
Small spaces appear between the granulosa layers due to cells secreting follicular fluid
- fluid accumulates, the spaces enlarge, and gradually coalesce
- granulosa cells reorganize themselves around a larger cavity, the antrum
What makes up the Theca?
Stromal cells proliferate into a stratified cuboidal epithelium called the theca
Theca interna: vascularixed cell layer adjacent to the basal lamina supporting granulosa that produces androstenedione that is converted to estradiol
theca interna: fibrous cellular layer that is continuous with ovarian stroma
characteristics of a mature Follicle and what happens to the granulosa cells?
also called a Graffian follicle:
- Antrum accumulates more fluid that reaches a size of 2cm
- get thick thecal cells
- bulges at the surface of the ovary that is visible with ultrasound
Granulosa cells will thin out and become segregated by fluid:
- Mural granulosa cells: line follicular wall, actively synthesized and secret estrogen and produce follicular fluid
- Cumulus oophorus: anchor primary oocyte to follicle, and makes a nutrient delivery channel
- Corona radiata: granulosa cells acnchor the zona pellucida
What happens in follicular atrsia?
During a typical menstrual cycle, one follicle becomes the dominant follicle and other primary and antral follicles undergo atresia due to failure of a follicle to ovulate
Apoptosis is the mechanism:
-ensures regression of the follicle with out an causing an immune response
the follicular atresia presents as a glassy membrane due to its thick folded basement membrane material
Ovulatory phase of the Follicle and what does LH cause?
Mature preovulatory follicle protrudes from ovarian surface forming a stigma on the ovary
Proteolytic activity of theca externa and tunica albuginea causes rupture and the follicle enters the uterine tube
LH surge causes the primary oocyte to complete meiosis I making it a secondary oocyte arrested in metaphase II
-oocyte undergoes ovualation and enters oviduct
Mural granulosa cells and the theca interna repair the ovarian surface epithelium (OSE) following the follicle rupture
Luteal phase of the Follicle
After ovulation, the residual mural granulosa cell layer folds and becomes part of the corpus luteum
- breakdown of follicle basal lamina
- blood vessels invade the empty antrum and blood flows and coagulates forming a corpus hemorrhagicum
The thecal cells begin to differentiate:
- Mural granulosa cells turn to granulosa lutein cells
- theca interna cells become the theca lutein cells
What does the Corpus luteum, granulosa lutein cells, and theca lutein cells do?
Corpus luteum promotes endometrial changes that support implantation
it is made up of:
Granulosa lutein cells:
- hypertrophic steroid secreting appearance
- secrete progesterone and estrogen with FSH and LH stimulation
- will express LH receptors witch is an essential step for luteinization
THeca lutein cells: that produce androstenedione and progesterone with LH stimulation
Luteolysis
if fertilization occurs:
- CL continues to produce progesterone and estrogen
- under stimulatory action of human chorionic gonadotropin (hCG) from the trophoblast layer
if fertilization does not occur:
- CL begins involution stage 14 days after ovulation
- regression of CL leads to formation of corpus albicans, which is a scar of Connective tissue (type I collagen with few fibroblasts)
- forms at the site of the CL after involution, gradually becomes very small
what is the oviduct
Paired ducts that provide fertilization microenvironment and transport of the embryo to the uterus
The wall consists of folded mucosa, a muscularis layers and a thin serosa covered by visceral peritoneum with mesothelium
Mucosal folds are most prominent in the ampulla whereas they are smaller closer to the uterus and absent in the uterine part
Infundibulum, ampulla, isthmus, and uterine part
where does fertilization occur?
in the ampulla of the uterine tube
Characteristics of the wall of the oviduct
Mucosal layer:
- simple columnar epithelium with lamina propria of loose CT
- Ciliated cells and secretory peg cells that are sensitive to estrogen signaling that make it increase in size
Smooth muscle layer:
- inner circular spiral layer and a outer longitudinal layer
- serosa layer with large blood vessels
Peristaltic contraction and ciliary activity propel the oocyte and the zygote toward the uterus
what three layers make up the Uterus and their specific characteristics
Uterine has three layers
Endometrium:
- epithelium is simple columnar with simple tubular endometrial glands
- functional layer is lost during menstruation and is supplied by spiral arteries
- basal layer: retained during menstruation
Myometrium:
- poorly defined smooth muscle
- central, circular layer with thick blood vessels called the stratum vasculare
- outer and inner layers contain longitudinally or obliquely arranged fibers
Perimetrium:
- serosa covering posterior surface and part of anterior surface
- remainder is adventitia
Endometrium vasculature
Arcuate arteries supply the endometrium
- straight segment supplies the basal layer
- coiled segment, supplies the functional layer that stretches with endometrial growth
Before menstruation contraction of the artery occurs at straight-coiled junction that reduces the blood flow and destroys the functional layer
What are the three phases of the Menstrual cycle? and what are their day lengths
Menstrual phase (1-4) Proliferative phase (5-14) Secretory phase (15-28)
what occurs in the Menstrual phase? and histological characteristics?
Days 1-4
- Corpus luteum regresses
- REduced blood supply leading to ischemia and necrosis of functional layer
- functional layer sloughs away and the basal layer is retained
- Constriction of spiral arteries leading to hypoxia
- swelling/breakdown of glands
- stroma of functional layer is sponge like
- breakdown of stroma matrix
what occurs in the Proliferative phase? and histological characteristics
days 5-14
- glands proliferative and cover surface
- spiral arteries elongate and become convoluted and extend from basal to functional layer
- Estrogen dependant
- functional layer is relatively thin
- stroma is more cellular
- glands relatively straight, narrow and empty
what occurs in the secretory phase and histological characteristics
days 15-28
- Endometrium reaches max thickness
- spiral arteries continue to grow and extend functional layer
- glans appear saw tooth
- estrogen and progesterone
- Functional layer less cellular
- 3-4x thicker than basal layer
- tubular glands have secretory product, zigzag saw tooth shape
Decidual Reaction
If pregnancy takes place, endometrial stroma undergoes histologic changes following implantation
- fibroblasts become enlarged, polygonal, more active in protein synthesis making decidual cells
- store lipids and glycogen, decidual reaction
this provides an immune-protective environment for embryo and moderates syncytiotrophoblast invasion
Entire endometrium is now called the decidua and separates into functional layers involved in placenta development
Characteristics and elements of the Cervix
Communicates with the uterine cavity and vagina through the endocervix cana;
-mucosa with crypts, branched mucus secreting tubular glands
Cervical crypts:
- increase surface area of mucus producing simple columnar cells
- height varies with the time of the menstrual cycle and secretory activity
- can be occluded and dilated forming nabothian cysts
Ectocervix: external cervical segment of the cervix lined with non-keratinized stratified squamous epithelium
Transformation zone:
-abrupt epithelial transitionbetween the endocervix and the ectocervix
important to get a pap smear of all three cell locations
Characteristics of the Vagina
Fibromuscular tube with 3 layers:
Mucosal layer: non keratinized stratified squamous
-kept moist by mucus from uterine/endocervical glands and glands of bartholin
Muscularis layer: circular and longitudinal smooth muscle
Adventitial layer:
-Dense Connective tissue
Mucosa will fully differentiate with cycling estrogen as stratification increases
