Histology IVF Female Reproductive
What surrounds the ovarian medulla and cortex
- Germinal epithelium - simple cuboidal - Tunica albuginea - DICT capsule
What are some immune defenses in the vagina?
- Lymphocytes in epithelium and lamina propria - Langerhans cells trapping antigens in epithelium - Bacteria lower pH i n lumen prohibiting growth of pathogens.
Name all the 6 cell stages of oogenesis.
1) Primordial germ cells 2) Oogonia 3) Primary oocyte 4) Secondary ooctyte 5) Ova 6) Zygote
Describe the histology of non-lactating, resting mammary glands.
15-25 lobes that converge and drain into single large lactiferous duct that opens at the nipple. Dilation beneath areola in duct is called lactiferous sinus. Duct changes to stratified squamous near nipple.
What is folliculogenesis?
4 stages of follicular development that begin at puberty under the stimulation of Follicle Stimulating Hormone (FSH). Makes up the follicular phase of the Ovarian cycle in preparation for 28d ovulation.
Which stages of oogenesis occur resume after puberty prior to ovulation?
4) Secondary oocyte (1n 2c) are formed when primary oocytes complete Meiosis I and arrests once again at Metaphase II. Ovulation releases the secondary oocyte. 5) Only during fertilization does the secondary ooctyte complete resume Metaphase of Meiosis II to form Ovum (1n 1c) gamete. 6) The zygote is formed from the fusion of pronuclei of ovum and spermatozoa.
What do Unilaminar primary follicles constist of?
A single layer of cuboidal granulosa cells and basal lamina forms with the zona pellucida forming them and the primary oocyte.
What is the transformation zone in the cervix endometrium that occurs after puberty?
A zone that during puberty the movement of epithelium beyond the external os and exposure to low pH of vagina induces squamous metaplasia , blockage of cervical glands, and formation of cysts called Nabothian follicles.
What happens to mammary glands post-lactation?
After a women stops lactating, the alveoli that developed during pregnancy degenerate while myoepithelial celsl and basal lamina persist and are reused in the future.
Describe the development of mammary glands after puberty.
Before puberty glands consist of system of ducts. After puberty these ducts grow and branch, as well as accumulat eadipose and collagenous tissue in response to increased estrogen and progresterone. These ducts can be lined by simple cuboidal, columnar epithelium of stratified cuboidal epithelium depending on the size.
What are the three regions of the uterus?
Body, fundus, cervix
What is the role of oxytosin in lactation?
Causes the contraction of myoepithelial cells surrounding the lobules leading to the release of milk stored in ducts/alveoli.
Difference between chorion and decidua basalis?
Chorion (syn-/cytotrophoblast) and decidua basalis (decidual cells) are the fetal and maternal portions of the placenta, respectively.
Describe the histology of pregnant mammary glands.
Chorionic somatomammotropin (placental), estrogen and progesterone induces epithelium at the ends of ducts to proliferate to form numerous secretory alveoli surrounded by myoepithelial cells. Glandular tissue tissue replaces connective.
What is colustrum that is secreted late in pregnancy into the lumen of the alveoli?
Colustrum is rich in IgA and is synthesized by plasma cells located in the intralobular connective tissue. It is expressed 2-3 days after birth and plays a role in passive immunity.
Describe the histology of lactating mammary glands.
Composed of glands with alveoli filled with milk. Contains irregular branching pattern of alveoli and ducts.
What cell is transformed in the uterus by the contact of the blastocyst to the uterine wall? What will these cells form?
Contact by the blastocyst onto stromal cells of the endometrium stimulates them to become decidual cels that will form the maternal portion of the placenta (decidua basalis).
Describe the vaginal muscularis.
Contains bundles of smooth muscle. At external opening a sphincter muscle with skeletal muscle fibers encircles the vagina.
How is the cervix distinct functionally from the fundus and body of the uterus?
Contains endocervical canal link to vagina. Provides secretions to vagina. Regulates entry into upper tract. Can dilate during parturition.
What are Secondary (antral) follicles and when are they observed?
Continued stimulation of the Multilaminar primary follicle by FSH and the theca by LH results in a follicle that is endocrine secreting and has a fluid filled antrum with plasma, glycoproteins and hormones.
What are Multilamina primary follicles and when are they observed?
Continued stimulation of the Unilaminar primary follicle by FSH develops 2+ layers of avascular granulosa cells around the oocyte + zona pellucida. The ovarian stroma surrounding the follicle begins to form the highly vascular Theca folliculi.
What induces the myometrium to contract during parturition?
Contraction is stimulated by prostaglandins from myometrium and fetal membranes and oxytocin from pituitary glands.
What which layer of ovaries is the site of oocyte development and endocrine function?
Cortex - outer region of parenchyma
What initiates the menstrual phase of the uterine cycle?
Degradation of the corpus luteum causes a drop in progesterone and estrogen levels. The functional layer of endometrium is lost.
What happens to mammary glands post-menopause?
Drop in estrogen levels causes glands to involute and be replaced by adipose tissue.
Name the three layers of the uteris.
Endometrium=mucosa Myometrium Serosa or adventitia
Describe the epithelium of the endometrium?
Endometrium=mucosa. The epithelium contains invaginations into lamina propria that forms tubular uterine glands lined by ciliated cells. Non-invaginated epithelium contains non-ciliated secretory cells.
Name the layers of placental barrier separating the maternal and embryonic blood supplies.
Endothelium of fetal capillaries + basal lamina; basal lamina of trophoblast, cytotrophoblast, and syncrytiotrophoblast.
What is necessary to maintain the corpus luteum during the Luteal phase of the ovarian cycle? What happens if this doesn't occur?
Estrogen and progesterone, secreted by the corpus luteum, negatively feedback to the pituitary to produce less LH. LH is necessary to maintain the corpus luteum and will degrade, unless... pregnancy occurs and the blastocysts and placenta secrete human Chorionic Gonadotropin (hGC) which maintains the corpus luteum in absence of LH stimulation.
How are bacteria in the vagina maintained?
Estrogen stimulation promotes storage of glycogen in epithelial cells of the vagina. As these cells are sloughed off they release the glycogen to feed bacteria such that they can produce lactic acid to lower the vaginal pH.
When are Unilaminar Primary Follicles observed?
Every month FSH increase stimulates some follicles to undergo folliculogenesis. Unilaminar primary follicles are the first follicles observed.
What are the major hormonal events that occur during the follicular phase of the ovarian cycle?
FSH stimulation induces the deveopment of primordial -> primary -> secondary -> mature (graafian) follicles. During which increasing levels of estrogen produced by the follicle induces the LH spike (and FSH) that allows primary oocyte to complete meiosis I -> secondary oocyte, and prepares the follicle for ovulation.
What are the three phases of the ovarian cycle?
Follicular phase, ovulation and luteal phase.
Describe the four anatomical regions of the oviducts and how they differ histologically.
From the open end to the uterine end, the muscularis becomes thicker, mucosa thinner, mucosal folds decrease, and lumen diameter decrease. -Infundibulum-funnel shaped, highly folded & branched mucosa, cilia-lined fimbriae. -Ampulla-longest region where fertilization typically occurs. - Isthmus-potential for ectopic pregnancy. -Intramural region - passes through uterine wall.
Describe the two regions of the endometrium by blood supplies?
Functionalis layer forms the upper 2/3 that is sloughed at menstruation and reformed under influence of estrogen and progesterone. Vascularized by spiral arteries. Basalis layer forms the lower 1/3 that remains intact and serves as the regenerative source for functionalis. Vascularized by straight arteries.
Which regions of the uterus are structurally similar?
Fundus and body
When are mammary glands capable of producing milk?
High levels of estrogen and progesterone during pregnancy stimulate mammary glands to produce milk due to expansion of ductal system.
What ends the secretory phase of the uterine cycle?
If pregnancy doesn't occur, the anterior pituitary ceases to secrete LH, which causes degradation of the corpus luteum, which decreases levels of progesterone. This causes the endometrium functional layer to disintegrate and menstrual phase to begin.
During the Luteinization phase of the Ovarian cycle, what follicular and hormonal events occur?
Luteinization in short is the maintenance of the corpus luteum in response to LH, for the secretion of estrogen + progesterone. After ovulation the ruptured follicle forms the corpus hemorrhagicus, which in response to LH forms the corpus luteum/luteal gland.
What is luteolysis?
Luteolysis is the degradation of the corpus luteum when LH levels drop and pregnancy does not maintain it. It will then form the corpus luteum of menstruation, rather than that of pregnancy. Once the corpus luteum ceases to function it is becomes the corpus albicans.
Describe the circulation in placenta.
Maternal blood fills the lacuna from decidua bassalis vessels. Nutrient and waste exchanges occur with the capillaries of the villi which will circulate the embryo. Blood does not mix due to placental barrier.
Name the three phases of the uterine (menstrual) cycle and the days they occur.
Menstrual phase (1-4) Proliferative (5-14) Secretory (15-28).
What three layers compose the walls of oviducts?
Mucosa - simple columnar epithelium composed of ciliated cells and peg cells, and have longitudinal folds. Muscularis - Peristalsis propels the oocyte or fertilized ovum towards the uterus.
How is the cervix distinct histologically from the fundus and body of the uterus?
Mucosa isn't shed and contains two regions: Endocervix-similar to endometrium but but mucous secretions are watery during follicular phase (high estrogen) and thick in luteal phase (high progesterone). Exocervix-protrudes into vagina and lined by a-glandular, stratified squamous non-keratinized epithelium.
Three layers of vaginal wall?
Mucosa, muscularis, adventitia
What happens to myometrium during and after pregnancy?
Myometrium smooth muscle cells hypertrophy and some new cells are added. After parturition the cells return to normal size but the overall region is thicker.
What is the functional difference between nonciliated peg cells and ciliated cells?
Nonciliated peg cells are secretory cells that provide nutrition to the ovum. Ciliated cells sweep in waves towards the uterus to direct the ovum.
What can pass the placental barrier?
Nutrients (O2, H2O, Electrolytes, Carbs, lipids, proteins, vitamins) IgG (passive immunity) Waste products (CO2, products of metabolism) Drugs, toxins, viruses, bacteria may cross.
When does the first arrest in oogenesis occur and at which stage? When does oogenesis resume?
Oogenesis stalls when oogonia begin Meiosis 1 in the 3rd month of gestation at prophase (diplotene) to form Primary spermatocytes (2n 4c). Here the DNA has already been duplicated, synaptonemal complex is degraded and chiasmatas are formed (crossover). Oogenesis resumes prior to ovulation (post-puberty) abd meiosis I is completed to yield secondary oocytes (1n 2c).
What are some structures found within the cortex of the ovaries?
Ovarian stroma - connective tissue + cells Ovarian follicles in various stages of development. -> Corpus luteum - temporary endocrine glands -> Corpus albicans - scar
What are Primordial follicles and when are they observed?
Primordial follicles are formed in the fetus and present at birth. They contain primary oocytes surrounded by a layer of flattened follicular cells and basal lamina. These form the majority of follicles in the ovary.
What are the four classes of follicles based on their stage of development?
Primordial, Unilaminal primary, Multilaminar primary, Secondary (antral) Mature (Graafian)
What is the suckling reflex and how does it control the production of prolactin?
Prolactin and milk production is dependent upon the suckling reflex. Mechanoreceptors in the nipple and alveola are stimulated by suckling and stimulate hypothalamus to continue production of prolactin by the anterior pituitary gland and oxytocin by posterior.
What initiates the proliferative phase of the of the uterine cycle?
Proliferative phase begins when menstrual flow ceases. Here an increase in FSH induces follicular growth which increases estrogen secretion. This stimulates the uterus functional layer to regenerate and uterine glands are reformed.
What occurs during the ovulation phase of the Ovarian cycle?
Proteases degrade the wall of the mature (graafian) follicles and the connective tissue at the stigma until the follicle ruptures into the peritoneal cavity. The cumulus mass (+ 2ndary oocyte) adheres to the surface of the ovary and is "picked up" by the fimbrae.
What is the role of relaxin hormone during parturition?
Relaxin induces lysis of the collagen in the cervical wall of the cervix allow for expansion of the endocervical canal during parturition.
What is the zona pellucida?
Space between the granulosa cells and oocyte which is made of glycoproteins (ZP1, 2, 3).
What are the steps of menstruation that cause the functional layer to slough off?
Spiral arteries constrict depriving functionalis of blood leading to necrosis during the first 2 days or so. The arteries dilate again and rupture. The disgorged blood removes functionalis causes menses discharge.
Describe the vaginal mucosa.
Stratified squamous non keratinized epithelium; transverse folds for expansion; aglandular; immunity and glycogen storage.
What are ovarian follicles?
Structures within the ovaries that house and provide a micro-environment for the developing ooocyte. In later stages of follicular development they also secrete estrogen and progesterone.
The proliferative phase of the uterine cycle corresponds to what phase of the ovarian cycle?
The antral phase of the follicular phase of the ovarian cycle where the follicles grow.
What forms the fetal portion of the placenta (chorion)?
The chorion is formed when the trophoblast cells proliferate and differentiate into: - Cytotrophoblast: inner layer, mitotically active and mononucleated. - Syncytiotrophoblast: external layer, mitotically inactive, and multinucleated (fused cytotrophoblasts).
What is the cumulus oophorus and corona radiata?
The cumulus oophorus is the group of granulosa cells that anchor the oocyte in the antrum to the follicular wall. While the corona radiata is the group of granulosa cells immediately surrounding the oocyte.
Which stages of oogenesis occur before puberty and what happens in each?
The first three stages of oogenesis occur during development: 1) Primordial germ cells (2n 2c) originate in yolk sac and migrate to genital ridges (Week 6). 2) Oogonia (2n 2c) are formed from the mitotic division of primordial germs cells in the fetal ovaries. 3) Primary spermatocytes (2n 4c) are formed when oogonia enter Meiosis I and arrest at prophase (Month 3). Here the DNA has already been duplicated.
Which is found in the innermost layer of ovaries?
The medulla composed of loose fibro-elastic connective tissue, large blood vessels, lymph vessels and nerve fibers.
What happens to the myometrium as it progresses towards the cervix?
The muscle tissues is gradually replaced by fibrous connective tissue.
Describe the myometrium of the uterus.
The myometrium is composed of three layers of smooth muscle: - The thick, highly vascularized middle circular layer is called the stratum vasculare. - Outer and inner are longitudinal muscle.
The menstrual phase of the uterine cycle corresponds what phase of the ovarian cycle?
The pre-antral phase of the follicular phase of the ovarian cycle.
How is estrogen produced from Secondary (antral follicles)?
The theca folliculi differentiates into a fibrous theca externa and androgen secreting, highly vascular and cellular theca interna under the stimulation of LH. Granulosa cells contain the aromatase necessary to convert the androgen produced by theca interna into estrogen in response to FSH.
What are the oviducts?
They are paired, muscular-walled tubular structures-the fallopian tubes and uterine tubes-where fertilization occurs.
What initiates the secretory phase of the uterine cycle?
This phase begins after ovulation when the corpus luteum secretes progesterone which allows the functional layer to thicken, spiral arteries to convolute, uterine glands to convolute and dilate accumulating secretory products.
What is the function of the placenta?
Transfer of nutrients and waste products, to and from the fetus, respectively. Endocrine production of hCG.
Describe the two cell types of the blastocyst.
Trophoblast - the single layer of epithelial cells which form the wall and give rise to the placenta and embryonic sac. Embryoblast - The small group of cells located at one pole within the fluid filled cavity that will give rise to the embryo.
Describe the blood supply to the uterus and its different layers.
Uterine arteries distribute blood to 6-10 arteries which feed the outer myometrium. Radial artery brances run centrally through myometrium until they reach the endometrium and branch into straight and spiral arteries that feed basal and functional layers, respectively.
What are 5 hormones secreted by the placenta and what is their function?
hCG - maintain corpus luteum Progesterone & Estrogen - maintain pregnancy Chorionic somatomamotropin - growth of mammary glands Relaxin - released at parturition to lyse collagen of cervical wall.
The secretory phase of the uterine cycle corresponds to what phase of the ovarian cycle?
Luteal phase where the corpus luteum secretes progesterone to wait for pregnancy to occur.
What are the two main processes that occur during the Luteal phase of the Ovarian cycle?
Luteinization and luteolysis phase.
What is the cumulus mass?
In the mature (graafian follicle) the secondary oocyte, zona pellucida, and corona radiata (GCs) break away from the follicular wall cumulus oophorus and floats freely inside the antrum.
What controls the secretion of milk in lactaing mammary glands?
Increased levels of prolactin stimulate the productino of milk that replaces colustrum and contains proteins and lactose (merocrine), and lipids (apocrine).
How does the cervical wall of the cervix differ from the body/fundus of the uterus?
It contains dense collagenous connective tissue with numerous elastic fibers.
What is the corpus luteum of pregnancy?
It is the corpus luteum maintained by hCG (post-pregnancy) that secretes high levels of estrogen and progesterone necessary for the maintenance of pregnancy.
What is a mature (Graafian) follicle?
It is the only follicle during folliculogenesis that continues to grow to a diameter of >10 mm in diameter and will eventually ovulate. In response to LH spike the primary oocyte complete Meiosis I and arrests at metaphase II. All other follicles undergo atresia to become atretic follicles.
What is the stigma of the ovary?
It is the thinning region on the surface of the ovary where the mature (graafian) follicle is located, become avascular, and germinal epithelium becomes discontinuous.
Describe the formation of the tertiary villi structure in placental circulation.
Lacunae formed within the syncytiotrophoblast fill with maternal blood from ruptured endometrial vessels. Primary villi are formed when a core of cytotrophoblast grows covered by syncytiotrophoblosts grows into lacunae. This primary villi is invaded by extraembryonic mesoderm to form secondary villi. Tertiary villi are formed when embryo's capillary beds develop within the villi.
