Histology Flashcards
How to find the cortex in an ovary
It is generally where the follicles are hanging out. the boundary between cortex and medulla is indistinct.
Why do ovary cross sections look so different
Depends on stage of cycle, age of ovary, and species
Follicles consist of…
an oocyte, which is then encapsulated by one or more layers of cells.
Primordial follicle
The follicles that the woman is born with. All that she will ever have. Must migrate to cortex and be encapsulated or they will die before the woman is born. This process is not cyclical and not hormone-dependent. Consist of the oocyte with single layer of flattened follicular cells (these are the ones that must be present in order for the cell to survive). Primordial follicle that is encapsulated with follicular cells will be arrested in first meiotic division. Once they migrate to the cortex, they will be surrounded by stromal cells.
Progression from primary follicle to secondary follicle to Graffian follicle.
Form sexual maturity until menopause Hormone-dependent (GnRH)
Stromal cells
Accumulate around the edge of primordial follicle after it migrates to the cortex; Become theca cells;
Secondary oocyte
After the oocyte has been ovulated.
Primary follicle
A primary oocyte within a primary follicle. Cells around the oocyte are now cuboidal and they’re called granulosa cells. There is a now a basal lamina/membrane that separates granulosa cells from the stromal vasculature. So the oocyte is also separated., therefore the developing follicle is avascular and must depend on diffusion of nutrients from surrounding stromal cells. Next, the granulosa cells undergo multiple divisions to make multiple layers called the zona (stratum) granulosa. This is the first sign of follicular recruitment. Stromal cells differentiate into 2 layers: Theca intern (work w granulosa cells to prod estrogen) and Theca externa (will develop into smooth muscle cells that will help with ovulation of the oocyte later on). Zona pellucida develops between granulosa cells and oocyte. Helps send signals and nutrient to the oocyte.
When are the cyclical stages of follicle development?
Froms sexual maturity to menopause. Three phases: follicular, ovulation, luteal phase. Lasts 12-14 days.
Zona pellucida
- develops in the primary follicle between granulosa cells and oocyte. Helps send signals and nutrient to the oocyte. - key role in fertilization. Acrosome reaction when a sperm penetrates the oocyte membrane, resulting in spillage of proteases that crosslink with proteins in zona to trap sperm and close the barrier. –> prevents polyspermy, which is embryonic lethal
Development of the secondary follicle
- Antrum begins to form - fluid-filled cavity in a hole of lost granulosa cells, that is important for follicular growth, maturation, ovulation
Mature graafian follicle
Marked by the development of a full antrum, pushing oocyte off the one side of the follicle. The oocyte and surrounding zona pellucida and surrounding corona radiata cellsa will ovulate from the graafian follicle, leaving behind the corpus luteum.
zona granulosa
the granulosa cells that are pushed the periphery of the graafian follicle by the antrum
cumulus oophorus
granulosa cells dividing the antrum into a horseshoe and bridging the corona radiata and the zona granulosa
corona radiate
the granulosa cells between the oocyte and the antrum
theca interna cells
next to the granulosa cells and involved in hormone production
theca externa cells
smooth muscle cells that are important for assisting ovulation
What is ovulated from the graafian follicle?
oocyte + surrounding zona pellucida + corona radiata
what happens to the corpus luteum after ovulation?
the antrum fills with blood, which clots. Zona granulosa cells become granulosa lutein cells; theca interna cells become theca lutein cells - both of these now produce progesterone to maintain the uterine lining until implantation.
Potential fates of corpus luteum
- Corpus luteum of pregnancy - if fertilization is successful. Enlarges. hCG from embryo tells corpus luteum to continue secreting progesterone (& estrogen). Becomes corpus albicans of pregnancy. 2. Corpus luteum of menstruation - pumps progesterone for about 12 days. Becomes the corpus albicans at end of cycle.
Estrogen secreted from follicle stimulates…
endometrial proliferation and at first inhibits FSH and LH.
Estrogen peak stimulates…
LH surge, which triggers ovulation.
corpus luteum changes hormone profile to produce….
progesterone. Estrogen is still there, but the progrestone is responsible for maintaining uterine lining and expansion of glands and arteries in the lining. It also suppresses LH and FSH.
Why is development of glands in the uterus important?
Glands produce glycogen. Glycogen is an early nutrient source for the implanting oocyte. There is not yet a placenta to get nutrients form mum.
What happens when progesterone rapidly drops
LH and FSH are not longer inhibited, endometrium is no longer maintained, and the endometrium sheds - new cycle begins.
Teal and orange arrows: what are they and what are their function?
Where is this slide taken from?
Teal arrows: Peg cells; produce nutrients to support the Graafian follicle. Nutrition provided is in addition to that provided by the corona radiata cells that were ovulated along with the oocyte.
Orange arrows: Ciliated cells; Cilia beat in unison to help move oocyte along oviduct
Taken from the ampulla of an oviduct. This is ciliated columnar epithelium studded with peg cells.
What layers are there in the ampulla of the oviduct?
Ciliated columnar epithelium
Lamina propria
Smooth muscle (2 layers that are indistinguishable on histology)
What tissues form the placenta?
The villi and syncytiotrophoblast (contributed by fetus) and functional layer of maternal endometrium, which contributes lacunae containing maternal blood supply.
Identify A and B
A: maternal lacunae (in life this contains maternal blood, but not on histology)
B: Villus containing fetal blood
What three layers compose the maternal fetal diffusion barrier?
Endothelial cells of fetal blood vessels, connective tissue of villus, and syncytiotrophoblast cells interface with maternal blood.
What is pictured?
This is a term placenta
Name the three layers of the maternal-fetus diffusion barrier and identify them.
What does the human umbilical cord contain?
Tw oumbilical arteries and a vein. The vein is atypical because it is muscular.
Name the substance that surrounds contents of the umbilical cord. What is it for?
Wharton’s jelly. Likely important for preventing collapse of the cord which may cut off blood supply to the fetus.
What is different about the cervical epithelium?
It is a transitional zone of epithelium. The epithelium of the endocervix is simple columnar epithelium. It extends into the uterus. The epithelium of the ectocervix is stratified squamous epithelium (continuous into vagina).
How does the cervix change with menarche?
Before menarche the two epithelia of the cervix are adjacent at the squamo-columnar junction. Later on, the columar epithelium starts to extend out to the ectocervix. The squamous epithelium responds by growing over top, creating a region of squamous metaplasia.
What do we call the area of the cervix where squamous epithelium grows over top of columnar epithelium?
The transformation zone of the cervix.
Name this structure overall and the area (A)
Oviduct; mucosa
What is the overall structure and what is in the area (A)
Umbilical cord; Wharton’s Jelly
Name the area the picture is.
What area is A?
What cells are at A?
What area is B?
What cells are at B (also an arrow)?
What is C indicating?
A: ectocervix; stratified squamous
B: Endocervix; simple columnar
C: Island of metaplasia where squamous grow on top of columar
Epithelium of the vagina?
Stratified squamous non-keratinized epithelium.
What do the arrows indicate? What is its purpose?
Smooth muscle of the vagina; allows for vast extension required for childbirth.
A: Testis
B: Epididymis
C: Vas deferens
What is A? What are its extensions (B)?
C and its function?
A: Tunica Albuginea; dense capsule of fibroelastic tissue - sends out extensions (B; septa) to support parenchyma.
C: Mediastinum testis; gateway for ducts, nerves etc to connect to the testis.
D: lobule (parenchyma)
What is encircled in yellow? Fxn?
A: what cells are here and what do they do?
Yellow: seminiferous tubule; exocrine (production of spermatozoa)
A: Leydig cells; produce testosterone.
What is this depicting?
From left to right-
Maturation of spermatagonia in seminiferous tubules.
Spermatogonia
Spermatocyte
Capsule
Spermatid
What do spermatids mature into?
Spermatazoa that are release at a rate of 300 million per day.
Support cells in the testis? How to identify them. Fxn.
Sertoli cells
They extend from the capsul to the lumen. Oblong with long extensions.
SUpport growth and maturation of spermatozoa.
Function of epididymus
spermatozoa storage and continued maturation
What is this slide from?
Describe the epithelium in the yellow box.
Epididymis
Pseudostratified with basal stem cells and tall principal cells with apical stereocilia, which increase the SA for absorption.
What is this? What are the layers of it?
Vas deferens
3 layers smooth muscle and pseudostratified epithelium similar to epididymis (basal cells, tall prinicpal cells with apical stereocilia)
What is this slide taken from?
What is stained red?
What is stained blue?
Prostate
Smooth muscle is red
collagen fibres are blue.
What are A, B, and C?
What encases each of these sections?
A: Corpora cavernosa
B: Corpora cavernosa
C: Corpus spongiosum
tunica albuginea encases each of the main sections.
Epithelium of penile urethra
Stratified columnar epithelium, changing to stratified squamous epithelium near its termination.
Name it. Fxn?
Glands of Littré; secrete mucus as a pre-ejaculatory secretion.
A: cortex
B: corticomedullary junction
C: medulla
What is pictured overall?
The renal corpuscle
A: parietal
B: visceral layer of bowman’s capsule
C: bowman’s capsule
D: bowman’s space
Identify distal and proximal convulted tubules in this slide of the nephron
Proximal convulated tubules (green) are more numerous, eosinophilic (pink), with a ‘shaggy’ lumen.
Distal convoluted tubules (yellow) are fewer, with smaller cells, less easinophilic (less pink), and a wider lumen due to the absence of a brush border.
Yellow is thick libs of loop of henle
Green is lin limbs of the loop of henle
What is pictured?
Collecting duct
What is pictured? Name the structure in the box of each number.
the ureter
1: epithelium
2. lamina propria
3: muscularis
4: adventitia
What is the name for the epithelium in the urinary tract? What are the cells on top? What tissue is at A?
It’s a transitional epithelium.
The cells on top are called umbrella cells because.
A: lamina propria of the ureter
What are the muscle layers of the ureter?
Inner longitudinal muscle, circular muscle, and outer longitudinal muscle
what are the general tissue layers of the bladder and ureter
Lamina propria
longitudinal muscle
circular muscle
outer longitudinal muscle
adventitia
Name the tissue layers identified by stars on this bladder wall
Inner longitudinal muscle
circular muscle
outer longitudinal muscle layer
What is pictured here?
Red star?
Red arrows?
Yellow circle?
Blue star?
Blue arrows?
Renal filtration barrier.
Red star: Lumen of the glomerular capillary endothelium
red arrows: fenestrations of capillary endothelium in glomerulus
Yellow circle: basement membrane
Blue star: podocyte process
Blue arrows: peducles of podocyte processes
What is between the peducles of podocytes in the renal filtration barrier?
The filtration slits.
What is indicated in blue? Its function?
Yellow?
Red?
Blue: Cells of the macula densa. Monitor Na levels in the DCT
Yellow: JG cells
Red: Granules full of renin that come from JG cells
What anatomic region of the kidney is portrayed in the entire field of view here?
In life, what substance occupied the space at the tips of the green arrows?
Collecting duct;
Glycogen
lymphoid nodule
lamina propria
microvilli of DCT
angiotensinogen
A: glomerulus
B: parietal layer of bowman’s capsule
A:Lymphoid nodule
B: lamina propria
What ultrastructural feature of the the urothelium of the bladder allows it to fold easily?
membrane plaques
