Histology Review Mod 2 PDF

HISTOLOGY REVIEW MOD 2 Respiratory System - Systemic histology mainly as a tube system o Middle with a lumen which means we will have a lining epithelium o Lining depends on what is going on in this tube, different areas of the body o Can contain air, diges...

HISTOLOGY REVIEW MOD 2 Respiratory System - Systemic histology mainly as a tube system o Middle with a lumen which means we will have a lining epithelium o Lining depends on what is going on in this tube, different areas of the body o Can contain air, digestive material, urine, blood, sperm, lymph, hormones etc. o In all tubes we will have minimum of 3 layers - 3 layers o Mucosal o Submucosal o Adventitia o Muscularis (not always) - Tube that starts at the mouth and ends at the alveoli - Divided into 2 segments o Conducting (nothing to do with the exchange of CO2 and O2 between air and blood) o Respiratory (makes sure oxygen goes in to the blood and CO2 goes out through exiting air)  Need to keep in mind that the epithelium and the sub-layer would be different in these 2 portions - Air coming especially today is very cold, we do not want air to be cold or dry, 2 things need to added so that our body temperature does not decrease  o Humidity o Warmth - This would be done at the entry point, at the nose and mouth - Epithelium of the nose is more important because we have the cells that capture smell - Pulmonary Airways: o Trachea - After the trachea: o Bronchi o Bronchioles  2 segments: terminale and respiratory  The terminale bronchiole has nothing to do with respiratory, just conducting  Respiratory bronchiole has to do with respiration  At the end we have alveoli - Trachea vs. Bronchi (L & R Above) o Trachea has a very big hyaline cartilage area for the C-shaped cartilage rings o Open at the back because behind we have the esophagus, have smooth muscle adjacent to esophagus which can allow the passage of a bolus of food behind, we do not want narrowing o Bronchi would have flaps of cartilage, only in the trachea and bronchi would we see cartilage in the respiratory system o Both epitheliums would have mainly 3 types of cells  Ciliated (usually columnar)  Allow mucous to move  Goblet cells  Secrete mucous, allow cilia to move without any issues, trap dust  Basal cells o Within the next layer, the submucosa we would see big glands that are sometimes seen in bronchi as well o Trachea has smooth muscle just in the layer lacking cartilage, in the bronchi we would see muscle surrounding all the areas o When we speak of asthmatic patients, vasodilators acts on this muscle starting on the bronchi and going to bronchiole - Bronchiole o Still conducting part o No cartilage at this point, lots of smooth muscle surrounding the bronchiole o When we exhale this skin collapses on itself because nothing maintains its rigidity  o To make sure it wouldn’t get stuck we have a cell that has replaced the goblet cells in the upper level, this is called the clara cell, this secretes surfactant like material that has some antimicrobial elements in it  Would not have to recognize it, rather understand what it is o Still we see the smooth muscle surrounding the bronchioles - Alveoli o Very small chambers, no cartilage, has to be very narrow because we see major transfer of CO2 for O2 o Epithelium has to be the most shallow for exchange of air o Clara cells become pneumocytes or alveolocytes type 2, prevents adherence of the “balloon” on top of itself, secretes surfactant that prevents this adherence o Still no cartilage! - Cells in Conducting Portion o Ciliated cells o Mucous goblet cells o Brush cells (sensors?) o Basal (short) cells o small granule cells (bronchial Kulchitsky cells)  thought to have neuroendocrine function (similar to enteroendocrine cell of gut (serotonin) (peristaltic?)) o Clara cells o Dust cells or macrophages as well - Trachea o Pseudostratified ciliated columnar epithelium, goblets cells o Glands in submucosa - Bronchous - Cartilage with smooth muscle below, still ciliated columnar epithelium - Know all the images in the lab image guide* - Terminal Bronchiole o No longer the cartilage flap and we see smooth muscle - Alveolar Sac o Pneumocyte 2 is bigger o Type 1 is very narrow Cardiovascular - Consists of: o Heart (muscular pump) o Pulmonary circulation (system of blood vessels to and from the lungs) o Systemic circulation (system of blood vessels bringing blood to and from all the other organs of the body) - 3 layers again and a tube, regardless if artery, vein, or heart o Tunics if it is a vessel, heart layers called differently - Most internal layer in the heart is the endocardium, mid layer in the myocardium (containing muscle), external most is pericardium and epicardium - Endocardium o Block-like cells that are actually nerves, very important for innervation IMAGE BELOW: Endocardium, Purkinje fibers, cardiac cell o Purkinje fibers are modified cardiac muscle fibers that are a part of the impulse conducting system in the heart* Structure of Vessels (3 main layers) o Tunica intima  Endothelium (epithelium of vessels) o Tunica media  Smooth muscle (differences between artery and vein in how big this tunic is, based on the same body region)  Cannot compare a large artery to an arteriole o Tunica Externa/ Adventitia- most external  Something that goes in adventitia and reaches the tunica media is called the vasovasorum  Small arteries, veins, nerves that supply the tunica media  If it is a big muscle layer it does not see enough oxygen from the lumen and needs more supply o Internal and External lamina in the artery separating the tunics from each other o Between tunica intima and tunica media in the big veins we have external elastic lamina but it would be discontinued o Tunica media of vein is much smaller Artery, Vein and Nerve - Artery is very circular and the vein is typically collapsed, this is because of tunica media, more muscles lead to more rigidity - Tunica adventitia is much bigger in the vein Coronary Artery - Coronary artery supplies the heart, very large muscular layer and lumen is large because the heart requires a substantial amount of blood, most important artery in our bodies Elastic Artery Muscular Artery - The aorta near the heart has to deal with changing pressure between systole and diastole up to 120 times a minute, needs to be very elastic, elastic fibers and smooth muscle cells adjacent to one another - Difference between elastic and muscular are the elastic lamina seen in adjacent muscle layers - Tunica adventitia starts after the last elastic line, will likely be on exam - Muscular artery we see nice black external and internal elastic lamina - As many layers of smooth muscle as elastic fibers in an elastic artery Capillaries - 3 types in different locations - Those that need a lot of blood flow exchange are completely sinusoidal  - The oxygen has to go out via the capillary beds, 3 main types of capillaries and the difference is in the permeability in the walls, either barely permeable or completely open allowing entire cells, or in the middle - We would like maintain a barrier in the brain (continuous), the testes (blood-brain barrier, blood-testicular barrier- we do not want infections or anything to go into the tissue, may kill us or sterilize males) - The capillaries in the brain or testes are called continuous testes - Sinusoidal where we want vitamins to cross in the renal system Video 2- HEAD AND NECK NOT ON EXAM Artery Vein and Nerve - Tunica adventitia is bigger than tunica media in the vein- helps to identify - Tunica media in artery is always bigger than in the vein (at the same level) Artery - In elastic artery in aorta between each adjacent muscle layer you also have an elastic lamina, an elastic layer (distinguishes whether it will be elastic or muscular) - Internal and external elastic lamina that you see is visible in both Capillaries - Fenestrated where we want many many things to cross over (sinusoidal capillary) - Equivalent to the width of one RBC- 6 to 8um Vein - Tunica intima is the upper most arrow head, small tunica media, no external elastic lamina, but we can a large tunica adventitia (as big as tunica media) - Remember tunica media is very small - Internal and external elastic laminas are nearly non-visible  - In vena cava (largest veins) you will see internal elastic lamina that is discontinued, will never see external - The upper central pointer designates the tunica media - This layer is thin and is composed of smooth muscle cells, collagen fibers and elastic fibers - The tunica adventitia is wide , It is composed of collagen and elastic fibers and fibroblasts and has layers of longitudinally oriented bundles of smooth muscle - The pointer in the adventitia indicates one of the smooth muscle bundles - In more superficial veins with no side by side arteries we need to interact against the gravity which means we need an additional muscle layer (e.g. saphenous vein), in tunica adventitia we have an additional layer which is probably perpendicular to tunica media muscle layer Lymph - Lymph system starts with veins, collects interstitial fluid and helps eliminate excess fluid or fluid from inflammation, returns fluids to the vein system - Has some kind of valves usually, on occasion cells in the lumen but not usually - tunica media would be bigger than veins in the same level - Tunica adventitia would be bigger, much more vaso vasorum (important for vasoconstriction, dilation and for oxygen to tunica media) than the arteries nearby, in tunica adventitia we would have perpendicular and oblique smooth muscle Urinary System - The Urinary system takes part in the removal of metabolic toxic by products from the blood. - It also conserve water, proteins, salts and glucose - Maintain acid base balance and help to regulate blood pressure - Main waste products are urea, uric acid, creatinine - Urine or filtrate collected in the bladder, we have some sphincters and then the urethra, main functional structure is the epithelium  - Kidney divided into capsulated circumference that protects it, sits in fat - The pyramids have an apex that is towards the calyx or the draining system, and the apex is toward the draining system, the tip is called the papilla which is the end point of the functional area of the kidney, urine is collected in this minor calyx (funnel) and then drains to the major calyx - All of the major calyx are drained into the hilum in a specific area called the renal pelvis, the hilum has a couple of structures coming in and out, coming in would be the renal artery, going out would be the renal vein and the ureter, the renal vein should have blood that is already filtrated - Identify the different areas, divide the kidney anatomically into 2 areas not including the capsule - (container or confinement) - First one is the cortex which we see at the circumference and as columns that are going inwards - In between the cortex we can see the medulla, in each one we can see different structures - Medulla has pyramids with orientation towards the pelvis of the kidney, papilla are pointed, apex is flat Juxtamedullary Nephron/ Collecting Duct Two Types of Nephrons - 85% are cortical nephrons o located almost entirely within the cortex (short nephron loop), perform most of the reabsorptive and secretory functions - 15% are juxtamedullary nephrons o located close to the medulla with long nephron loops that extend deep into the renal pyramids, create conditions for production of concentrated urine - Cortical nephrons perform most of the reabsorptive and secretory functions - Juxtamedullary nephrons create the conditions necessary for production of a concentrated urine - those 15% are the ones that in cases of water deprivation will conserve the water, making the urine more concentrated (extremes where we need to conserve, not drinking for a few days) - To each collecting duct we have many nephrons, each nephron is further on subdivided into different regions - The beginning of the filtration starts at the joint area between the vascular system and urinary system, this structure is called the renal corpuscle - Renale corpuscle divided into glomeruli which belong to the vascular system with afferent entrance and efferent exit of blood supply - Catching the urine after the filtration is the bowman’s capsule ending at the urinary where the proximal convulated tubule begins, it continues to the loop of henle descending limb with tboth thick and thin area then a loop followed by ascending thick and thin limbs that goes into the distal convoluted tubule which then finishes into the collecting duct Epithelium  - Simple epithelium starting with cuboidal with lots of villi in proximal convulated tubule because we need to re-absorb water and salt content (sodium chloride), potassium, magnesium - In the distal convulated tubule we do not have microvilli to the same extent Juxtaglomerular Apparatus - Very important because the physiology of it is to figure out what is going on at the point, it is like a quality assurance for the viscosity, osmolarity etc. of the urine going into the collecting duct- really the last point - The distal convulated tubule is very close to the vascular pole of the renal corpsucle - We can see macula densa cells that are very important and act like chemoreceptors to see what is going on with the osmolarity of the urine (is it concentrated or not concentrated) - If there is a discrepancy it can be dealt with by submitting signals to adjacent cells, to the left and just below the macula densa we have JG cells - JG cells are the second portion of the JG apparatus and would secrete renin and thus have influence on the blood pressure, located on afferent arterioles - JG apparatus is within tunica media of the vessels, so another possibility to do vasodilation and constriction on top of secreting renin Bowman’s Capsule - Visceral and parietal levels - Visceral is the region on top of the glomeruli, these cells on top are called podocytes, like fingers with slits, slits act like a funnel because you need to filter the blood that is going out of the glomeruli, glomeruli acts like sinusoids with very small holes so some ions could go out, but not proteins like keratin, if this is found in the urine this could indicate kidney failure - Podocytes make sure the slits are maintained, this is the actual visceral lining - Dealing with pathogens are cells that we call mesangial cells, blue in the picture above Ureter Tunica Mucosa- transitional epithelium above  - Located outside of the kidney - Star-shaped lumen - In this lumen we have lining of transitional epithelium, it can inflate when we need to increase the amount of urine - Again we see lamina propria (very large) as a greenish colour in mucosa layer and on circumference we see different muscular layers, key difference to digestive is inner layer is longitudinal (circular in digestive) Kidney-Cortex (18.00) - We see the renal glomerulus with the macula densa inside - Cells with elongated nuclei are efferent or afferent, where we find JG cells, many of these words as examinable material - The renal glomeruli are only in the kidney’s cortex, not in the medulla Kidney- Proximal Medulla - We see those life-savers, those with smudges in the middle would be proximal, those who are clear are distal convoluted tubuli - We also see loop of henle, a very thin area with thin cells Kidney- Distal Medulla - We see collecting ducts, elongated tubes with cuboidal lining epithelium Digestive System Alimentary Canal  - Understand the fact that the entire GI tract has the same levels - Most intimate would be the mucosa layer o Including epithelium which is changeable between stratified squamous epithelium in the esophagus going into columnar/cuboidal with microvilli, some without, and going back to stratified squamous at the end o Lamina propria with lymph like patches in the ileum, jejenum o Outer layer we have muscularis mucosa o Mucosa layer is subdivided into 3 portions (epithelium-inner most, lamina propria- adhering layer, muscularis mucosa- needed to move things) - Submucosa o Very interesting because in 2 areas of the GI tract we would have glands:  Esophagus- lubricate the food going down the tube  Duodenum- glands in the submucosa of duodenum called Brunner’s glands that secrete bicarbonate to contradict the acidic pH that comes from the stomach - Muscularis Externa o Mainly 2 layers, circular (inner) and longitudinal, outer most adventitia o Myenteric plexus to allow peristalsis - Serosa (adventitia) Esophagus - Stratified squamous epithelium - Lamina propria - Muscularis mucosa - Submucosa o Esophageal glands proper to lubricate the system and allow smooth movement of the food - Muscularis externa- muscularis propria  - We will also see some aurbach nerve plexuses Stomach- Different Lining - In the stomach we have fundas, body, pyloric region with different layers - Mucosa appearance - Gastric pits with the neck area and the gland, each region have specific cells, each cell with a specific task Fundic Glands - Some cells secrete mucous to ensure we have both mechanical and enzymatic/ chemical digestion, needs to move and be lubricated - Some cells for regeneration, top cells would die over time - Extends for muscularis mucosa to base of gastric pit divided to: isthmus, neck and base Parietal/Chief Cells - Blue (oxyntic) and yellow (zymogenic) - Located more towards the bottom because those cells secrete HCl to create acidity, ideal conditions for enzymes (gastric intrinsic factors that allow absorption of B12) Duodenum - Big villi with krypts in the mucosa, not just pits but some elevation - Elevation due to necessity of increase in surface area, absorbing nutrients from food beat up in stomach mechanically and enzymatically - Brunner’s glands in submucosa secrete bicarbonate (basic) to interact with HCl from the stomach - Main absorptive cells are enterocytes, make the majority of the top cells Esophagus- Lab image - Mucosa divided into epithelium below, then lamina propria, muscularis mucosa at the outer level, followed by submucosa (some areas we would see glands), then we have a very large muscularis externa  - Aurbach Plexus is shown, parasympathetic innervation - Depicts the epithelium, also the 2 layers of muscle (circular and longitudinal) Stomach- lab image - Parietal cells and chief cells dealing with enzymes and HCl - Again gastric pits with gastric glands at the bottom - Understand the difference between the parietal and chief cells, their secretants (theory) Duodenum- lab image - Know this over the other 2, one thing that gives it away is the Brunner’s glands in the submucosa, and all the tunics - Enterocytes are within the villi and microvilli, they secrete mucous but mostly absorbing nutrients, main function of the duodenum o Cannot get nutrients into body if there was a tumor here - Another aurbach plexus between the 2 muscular layers, also found in the submucosa (remember) Ileum- lab image - Just know we have once again absorption and in both duodenum, ileum, jejunum We have cells called paneth cells (secrete immune things) killing bacteria to avoid infection in the ileum Colon - Not much absorption if any at all, mucous and muscular layers Liver- Video 3- lab image - In the middle of each classic lobule one can see a central vein, all of the central veins would deliver blood that is already detoxified and has the things the body needs e.g. hormone backbones, vitamins - There are also lobes cannot see, but know they are there because they have a functional meaning - Portal lobe is triangular, each of those angles is starting with a central vein, and in the middle of this portal lobe is in the portal triad, contains: o portal vein or venule o hepatic artery or arteriole o bile canaliculi - All the bile from the portal lobe is going toward the triad, dealing with portal lobe is dealing with the movement of the bile - Last functional lobe is the hepatic acinus, diamond shape area that deals with flow of blood from the triad area or from the septum between the 2 classic lobules towards the central vein - Blood goes both from the portal vein and hepatic artery towards the central vein, in the middle it moves all the toxins and stuff that needs to go into the liver and collects things it needs like glucagon Pancreas (Endocrine/Exocrine system)- Lab image - Islands of Langerhans, small islands with pinkish areas that secrete important hormones - Hormones secreted by alpha, beta and delta cells a) insulin b) glucagon c) somatostatin Hepatic Organization/ Classic Lobule - Each arrows indicates an area of the triad where we would see bile canaliculi, hepatic arteriole and portal venule, in the middle of this system we have the central vein - 3 different types of lobes, we can see the classic lobule, portal lobule, triangular, and hepatic acinus blood flow Sinusoid - Within the sinusoid we have a macrophage designated to this specific region for it something bad occurs, in respiratory it is the dust cell - Kupffer cells are the macrophages within the livers, sits in the liver in the space of disse and waits for microorganisms or other issues in the blood Pancreas- previously mentioned Endocrine System Thyroid- Lobules - Extracellular storage is not as common, T3 and T4 are secreted into the large lumen, both would increase metabolic activity in all the organs we have covered, starting with the brain and going to digestive, bones, heart etc. - Calcitonin regulates the amount of calcium in the blood, when secreted we have decreased calcium in the blood, it acts directly on osteoblasts of bone - Within thyroid gland we have some small islands or pouches that belong to parathyroid glands (green) - Within the thyroid gland we can see rings built up by follicular cells, each of these rings have a lumen within and are called a follicle - The lumen is called colloid  - Easiest to recognize the colloid and follicular cells that make one big follicle, or make T3 and T4 hormones inside the colloid, when we need them it would go out via the follicular cells - Follicular cells allow the transfer of iodine into the colloid and would also make thyroglobulin protein or macromolecule - In between the follicles we have regions with nice cells, those that are not surrounding the colloid - If cell is not touching the colloid they are called parafollicular cells secreting calcitonin (know what it does- decreases blood calcium, involved in absorption) Parathyroid Hormone - Do not have to recognize it in practical, but PTH hormone contradicts calcitonin, maintains homeostasis in blood, both act on osteoclasts - The effect is mediated by a stimulation of osteoclastic bone resorption, intestinal calcium uptake and calcium resorption in the kidneys, increasing blood calcium - Without enough PTH we have tetanus of the muscles, muscles need calcium and if it does not have it, goes into a stress Adrenal Gland  - Two types of glands towards the bottom - At the top we see below the purplish line the capsule, below it a small layer with small globular football like structures, zona glomerulosa (secreting corticosteroids including aldosterone), interacts with homeostasis or salt in our blood - Next is the zona fasiculata, parallel cells and fascicles going from top to bottom, cells within those fascicles secrete glucocorticosteroid (deals with glucose, from the cortex, has a steroid backbone of steroid), one of them is cortisol- anti-inflammatory, secreted and maintained levels - Inner most layer is the zona reticularis, mismatch of cells and these cells secrete androgens (sex hormones- testosterone) - Last is the medulla, comes from the neural crest embryonically, secretes adrenaline and noradrenaline (epinephrine, norepinephrine) Lymphoid System- Thymus - Deals with two main white blood cell types - B (bone marrow) and T (thymus) cells - Thymus is made by small lobules, each with 2 distinct areas, one that is more purple and dark and one that is much lighter, in the cortex you would have more immature thymocytes then you would in the medulla - Out of the 100% thymocytes that are coming from the bone marrow to be educated in the thymus, just 5% will stay alive, the other 95% will die by macrophages and other types of cells - Why we see the purple in the cortex and less in the medulla Medulla - Once cells educated, a bit of knowledge of themselves (since too much or too little of the self they would be killed), these T cells are matured - In the medulla we have vortex like structures- Hassel’s corpuscles with endothelial reticular cells type 6 - Thymus is the first education and partial maturation of T cells Lymph Nodes (120 note service) - Paracortex, cortex and the medulla, difference is mainly between the cortex and paracortex - Within cortex we would see lymphoid follicles as small rounded structures - Some of them have an inside that would be more pale, depends on maturation of this follicle - If lymphoid is under attack from outside, all of these follicles would interact with a pathogen and more B cells would need to be educated - In the cortex there are areas for the follicles to mature into B cells and be educated, product of those follicles would be two types of cells that belong to the B cell: o Plasma cells- secrete antibodies o Memory cells- circulate within our body, remember interactions with e.g. influenza, memory cells remember this strain so the body does not have issues with fighting it years later- immunization concept - Primary follicles do not have the mantle around the pale area, no memory cells, just B cells, no plasma cells - Secondary have both memory and plasma cells  - Inside area is called the para-cortical region and has mainly T cells Spleen - 2 main regions to two types of pulps o Red o White - Red pulp is the graveyard for RBCs - White pulp is made by lymph follicles (just discussed) and the para-arterial lymphatic sheath - Most of the cells of PALS are re-circulating T cells, but nodules containing B lymphocytes also occur - White and red pulp both contribute to B and T cell education areas Tonsils (MALT): Form a ring around the pharynx - Invaginations of surface epithelium extend down into the lymphoid tissue forming crypts. Exocrine - Intercalated duct adds bicarbonate - Serous cells secrete alpha amylase - Striated excretory duct secretes potassium, absorbs sodium, and secretes antibodies into saliva Male Reproductive System Testes - Contained within the scrotal sac or scrotum - Includes endocrine (testosterone) and exocrine (sperm) - 3 Layers  o Outermost called Tunica vaginalis (visceral) o Middle Layer called Tunica Albuginea (dense collagenous fibrous) o Inner layer called Tunica Vasculosa (loose irregular w/ lots of vessels) - Blood needs to be chilled that goes to the testes to lower temperature so sperm is fertile (more veins then arteries) Seminiferous Tubule - the first station for sperm production - Each lobule has 2 rete testes which come together and become the ductus deference, and then becomes epididymis - The ducutus deference takes sperm into the prostate. Layers: - Dense outer layer – connective tissue with basal lamina (epithelial layer where sperm starts) - Notice connection in between sertoli cells. The junctions subdivide the lumen into basal and admunical compartments. - Sertoli cells support developing spermatogenci cells, establish the blood testis barrier, phagocytosis of waste products and make androgen binding proteins and other things. - Basal Area where the spermatogina are. - Question on the exam ** Spermatogonia then turn into spermatocyte primary then secondary) then spermatids (without tails) then spermatozoa - All elements of sertoli cell – secretes hormone and withdraws cytoplasm - Leydig cells secrete testosterone - Don’t need to know specific stages of spermatogenesis - EXAM question  Rete Testes - Communicating channels between the straight tubules and efferent tubeles (ductules). No smooth muscle present, lined with simple cuboidal cells Ductus Efferentes - Pseudostratified ciliated columnar epithelium - Cilia help propel spermatozoa along their journey Epididymis - Cells are more columnar - An absorptive and secretory organ - Absorbs excess fluid that’s passed out of efferent ducts - Produces glycoprotein material that coats the sperm - At apical layer there are sterocilia (not true cilia because they don’t move things) only function is to absorb fluid that once was cytoplasm of the cells that sertoli cells may of missed Ductus Deferens (aka Vas Deferens) - Carries sperm from epididymis to the urethra - Sperm can be shot up to 2 meters …they are accelerated by muscles in the vas deferens (3 Layers of muscle – 2 longitudinal and 1 circular) - **The muscle and how big it is what differentiates the vas deference from the ureter*** - Associated Glands (Seminal Vessicleprostate glandbulbourethral gland) - There are lots of mitochondria in the tail of the sperm that need to be fed sugars Seminal Vesicles - Coiled tube - Secretion constitutes 60-70&% of ejaculate and contains mainly fructose, and lipochrome pigment (yellowish color) Prostate - Gland engulfs urethra adds secretant that is added to the sperm that has enzymes that makes sure the sperm is protected in the female Cowper (Bulbourethral) Glands - Secreting lubricating solution directly into the urethra - Neutralize pH of urine Penis - Corpus cavenosum and corpus spongiosum are filled with blood during an erection Female Reproductive System Ovaries - Located within the pelvis, almond shaped - Each oocyte surrounded by a “primordial follicles” - When FSH stimulated the follicles, they enlarge and become encapsulated by connective tissue called “stroma” Oogenesis - First type of follicle – primary follicle - When oocyte can’t receive enough food through diffusion there is a chamber that opens up forming an antrum (now classified as secondary follicle). It then grows to the size of an ovum – most mature type that bursts out of the ovary and keeps everything 1) Primordial - Single layer of flat follicular (granulosa) cells. Granulosa cells protect the oocyte 2) Primary - Flat shaped cells change to cuboidal that engulfs oocytee. Without chamber its still primary follicle - Zona peluccida helps to protect the oocyte 3) Secondary - Granulosa/stromal cells in most inter surface (around antrum) change (theca interna)  - These secrete hormones. 4) Graafian – multiple layers - Thecas, antral cavity, corona radiata, cumulus oophorus - Theca cells surround the granulosa cells going around perimeter of the antral - Gronulosa cells release estrogen and progesterone - Cumulus is degraded from the theca interna as it then floats Ovulation: Process of releasing the oocyte from the graafian follicle Corpus Luteum - Formed from the remnants of the graafian follicle it is a temporary endocrine gland that manufactures and releases hormones that support the uterine endometrium - Granulusa Lutein cells – these were the granulusa cells from the graaifian follicle that differentiate into the hormone producing cells progesterone and estrogen - Theca Lutein cells – derive from the theca cells in the graaifan cells produce androgens and progesterone Oviduct - The oviduct functions as a conduit for oocyte, from ovaries to the uterus - Ampula = enlargement – where fertilization takes place - Intramural portion of fallopian tube is the entrance to the uterus Mucosal Layer - Secretory cells are called the peg-cells: They secretes nutrients that help the oocyte in its journey towards joining of the sperm - Then after fertilization occurs it supplies nourishment for the embryo - Cilia help move the ovum towards the sperm - Hormonal changes also influence secretion of peg cells and movement of the cilia in the epithelium Muscularis - Muscularis has 2-3 layers depending on location that help propolate the sperm and embryo. - Consists of inner circular layer and outer longitudinal layer - Inner longitudinal layer is present in the isthmus and the intramural part of oviduct (peristaltic muscle action) Uterus - Fundus is broadest and base of the uterus and narrowest at the cervix - Layers: o Perimetrium: layer that covers everything o Myometriun: The thickest layer o Endometrium: Innermost layer of the uterus  Two Layers: 1) Functional: Sloughed off at menstruation 2) Basal: Retain at menstruation, source of regeneration Hormonal Regulation - Ovary undergoes cyclic changes that include the follicular and luteal phase; with ovulation between the two phases - Increased levels of estrogens and progesterone make follicle independent of FSH - HCGH located in the urine and is tested for in pregnancy tests Menstrual Cycle Menstrual phase (1-4d) – necrosis and shedding of functional layer. Spiral arterioles constrict resulting ischemia. Proliferative (4-15d) – regeneration of functional layer, controled by estrogen secreted by granulusa cells (secondary and graafian, formation of straight endometrial glands. Ovulatory (14-16d) – peak of LH Secratory (15-25d) – secratory activity of endometrial glands, controled by progesteron. Endometrial gland become convoluted with secretion product Premenstrual (25-28d) – reduction of estrogen and progesteron leads to ischemia, glands begin to shrink Vagina Layers: - Mucosa: Stratified squamous epithelium and lamina propria (no glands) - Muscularis: Inner circular and outer longitudinal - Adventitia EMBRYOLOGY Parts of the GI Tract Most cranial – foregut ** usually on the exam! - It has 2 regions: oral cavity (pharynx), up to respiratory diverticulum and also the first portion of duodenum. It also has esophagus, liver, gallbladder, stomach, opening of bile duct, and pancreas - Lungs start from the respiratory bud off of the esophagus, the buds then split into two bronchial buds - Esophagus reaches its relative length by the 7th week - Stomach: Dorsal side of the stomach expands/elongates longer then the ventral side. The stomach rotates from dorsum/ventrum to horizontal. A pocket that starts to initiate from top and bottom mesentery - Development of Duodenum, liver, pancreas and biliary apparatus: o Everything starts as buds off of the main duct o Stomach – starts as a cylinder and swells unevenly, side by side rotate clockwise 90º and upwards to a transverse position. o Liver – develops in the ventral mesentery from a diverticulum. o Duodenum – arises from caudal part of foregut and cranial part of midgut thus it has dual arterial blood supply. It rotates clockwise with the stomach. o Pancreas – develops from endodermal lining of duodenum from a ventral and dorsa buds. With rotation of duodenum the two part will fuse.  o Divided into two portions (head and tail) that come from two different areas - Ventral and dorsal parts of the pancreas join each other - Spleen Development: The spleen arises in week 5 within the dorsal mesogastrium as proliferating mesenchyme overlying the dorsal pancreatic endoderm. Cells required for its hemopoietic function arise from the yolk sac. - Hepatic Growth: Liver grows bigger and is held by two mesenteries/ligaments (lesser and calceiform) Midgut - Remaining of the caudal duodenum (2/3) and ileum, jejunum, and a portion of the colon (ascending and transverse) - The midgut begins to elongates towards the umbilical cord. One area will begin to elongate quicker (small intestine) then the other (large intestine). - Counterclockwise twisting o Step 1) counter clockwise twisting 90 degrees o Step 2) twisting another 180 degrees o Ends at 270 degree counterclockwise turn. This occurs simultaneously with the intestine elongation. - In order to initially fit the entire midgut into the small body (abdomen) it needs to go into the umbilical cord until the abdomen gets bigger then it is retracted out of the umbilical cord. Hindgut - Remaining portion of colon (sigmoid) renal canal, and anus Limb Development - SHH: Plays a key role in organogenesis in vertebrate (growth of digits and brain organization). - Zone of Polarizing activity: An area of mesenchyme that contains signals, which instruct the developing limb bud to form along the a/p axis. - HOX: specify the anterior-posterior axis and segment identity of organisms during early embryonic development. These genes are critical for the proper number and placement of embryonic segment structures - 3 Stages of Limb Development: 1) Paddle stage: Originate as outgrowths of the lateral plate inside the mesoderm. Three planes are visible - Craniocaudal, proximodistal, and dorsoventral. 2) Plate Stage: Characterized by the formation of flattened plate-like areas on the distal ends of the limbs. - There are radially arranged thickenings called “Digital Rays” (to become digits). - Thin areas are called “Interdigital Grooves”. - “Primary Constrictions of the limb”: These constrictions will develop into wrists and ankles. 3) Rotation: Occurs along the proximodistal axis. - The upper limb undergoes a rotation in an opposite direction to the lower limb. - Upper limb rotates laterally (90) & lower limb rotates medially (90). - End result: Brings us to the endpoint of rotation of 180 degree (flexors in arm are in the front vs. flexors of the leg are behind) First Stages of Limb Development - End of week 4: Lateral mesoderm grows laterally, and is covered by the ectoderm. - Upper limb buds appear first (day 26-7), lower limb 1-2 days afterwards - Apical Ectoderm Ridge (AER): Thickening of the apex of each limb bud - Concentration of growth factor on the AER which signal growth  - The mesenchyme adjacent to the AER consists of undifferentiated, rapidly proliferating cells, whereas the mesenchymal cells proximal to it differentiate into blood vessels and cartilage bone models - Day 44: The distal ends of the limb buds eventually flatten into paddle-like hand & footplates. Apoptosis of loose inner-mesenchyme create finger webs - 5th week: Bones elongate - 5-6th week: Chondrification centers appear - 7th week: Osteogenesis of long bones begin - 12th week: Primary ossification center present in all long bones Muscles - Dermomyotome regions of the somites - Myogenic precursor cells migrate into limb bud & differentiate into myoblast - 2 big muscles started at the beginning: flexors (ventral) & extensors (dorsal) Nerves - 5th week: Motor axons arise from the spinal cord and enter the limb buds and grow into dorsal and ventral muscle masses - Sensory axons enter limb buds after motor axons and use them for guidance - Peripheral nerves grow from developing limb plexuses into the mesenchyme of the limb buds Blood - Limb buds are supplied by branches of “inter-segmental arteries” which arise from the dorsal aorta & from a fine capillary network through mesenchyme - Primary axial artery Embryology of the Heart - Day 17: Vessels arise from aggregation of endothelial precursor cells in splanchnic mesoderm o Vasculogenesis: Beginning organization of blood vessels o Angiogenesis: Branching of the existing vessels - Cardiac Coelom: Heart tube, Outer myocardial membrane, and inner myocardial membrane Cardiogenic Field (Folding) - Lateral folding of the body occurs - ALSO caudal to cranial folding - This puts the heart (from an above position) to below the head Formation of Cardiac Loop  - Bulges start forming - 1st bulge – bulbous cordis – first embryonic reprasentative of the outflow vessels (pulmonary vessel, aeorta, right ventricle) - 2nd bulge – primitive ventricle (left ventricle) - 3rd bulge – primitive atrium (big portion of right atrium) - 4th bulge - sinus venosus Formation of the Primitive Blood Vessels - Paired aorta makes the primary outflow vessels develop in the dorsal mesenchyme at both sides of the notochord - Cranial ends of the aorta make the first aortic arch - Angiogenic cord – become the aeorta and the heart - 4th week: main vessels Partitioning of the Heart - Starts with one folded tube - Day 28-37: Main sectioning occurs - Fusion of Primum & Secundum - Opening in septa=blood shunting RL - Septum secondum is formed from cranial side, then foramen secondum is formed in the septum primum  - Septum secundum is thick muscular, while primum is thin Separation of Ventricle - End of 4th week: 2 important processes 1) Muscular ventricular septum 2) Anterior papillary muscle Atrioventricular Valves - 5th-8th week: Formation of trabeculae derived from endocardial cushion - Left only anterior and posterior: Bi-cuspid - Right develop also a third valve on the third month: Tri-cuspid Fetal Circulation  Deoxuigenated blood conducted from the Umbilical arteries to the placenta (common iliac)  Oxygenated blood comes from placenta to IVC via the umbilical vein  Reaching the heart the blood goes through foramen ovale to left atrium and rest with SVC blod to right ventricle  Throughout the entire pregnancy the fetus does not get 100% fully oxygenated blood at any time.  Renal duct – towards kidney  Ductus arteriosus – shunt towards aorta. Right ventricle to pulmonary trunk  Ductus Venosus – shunt which bypasses the lives and puts blood into the hepatic veins.  Blood from placenta will be oxygenated and travel to the liver (vitamins) and also to the Inferior Vena Cava via the shunt Neonatal Circulation - Two shunts close (collapse) because the lungs start working - Sinus or ligamentum venosus/arteriosus after lungs start working in the baby Adult Derivatives of Fetal Vascular Structures FETAL STRUCTURE ADULT STRUCTURE Foramen Ovale Fossa Ovalis Umbilical Vein (intra-abdominal part) Ligamentum Teres Ductus Venosus Ligamentum Venosum Umbilical Arteries and Abdominal Medial umbilical ligaments, superior ligaments vascular artery (supplies bladder) Ductus Arteriosum Ligamentum Arteriosum