A tissue is an aggregate of cells and their products, united to perform a common function or functions. Four major types of tissues are recognized.
Epithelia
Epithelia are located on the free surfaces of the body. They cover the external body surface; they form the internal linings of hollow organs such as the stomach, trachea, blood vessels; and they line the body cavities. Epithelia do not occur alone, but are attached to and supported by some type of connective tissue. The latter also supports nerves and blood vessels necessary to the maintenance and functioning of the epithelia.
Such combinations of tissue form the "membranes," such as skin, mucous membranes, serous membranes, the tunica intima ("inner lining") of blood vessels and the endocardium of the heart. Other epithelia are organized into glands, e.g., liver, pancreas, salivary, sweat.
A. Simple Epithelia (one layer of cells)
1. Simple Columnar: gall bladder lining; small intestinal lining - note the microvilli, too; colon lining - note absorptive cells and goblet cells in its lining.
2. Simple Cuboidal: Thyroid gland follicle cells
3. Simple Squamous: Eye - look at the inner layer of Cornea; Lung -look at alveolar lining
B. Stratified Epithelia (multilayered)
1. Stratified Squamous: esophagus; vaginal lining; Stratified Squamous.
2. Stratified Cuboidal: Ovary - growing follicles
3. Stratified Columnar: Sweat gland duct.
4. Transitional: Urinary bladder lining
Identify epithelia on the following slides and note cilia wherever present: Skin, Tongue, Anorectal Junction, Duodenum, Trachea and Vagina.
I. Connective Tissue Proper
A. Loose Fibrous and Areolar Tissue. Chiefly found in subcutaneous tissue and in te lamina propriand submucosa of the G.I. and respiratory tracts, the intermuscular septa and serous membranes. Look at loose connective tissue underlying epithelial linings and within the walls of the following:
-> Wherever possible, identify on the above slides, these characteristic cell types:
- Fibroblasts
- Macrophages; also try lymph node. Recommended slide: Colon1
- Mast cells. Recommended slide: Colon 2
- Adipose cells; also try mammary glad; skin.
- Plasma cells (also try lymph node)
Note: also present are white blood cells and red blood cells within vessels, but save these until Blood Lab!B. Adipose: These are cells whose cytoplasm is occupied by a single large globule of lipid. The lipid droplet pushes the nucleus to one side of the cell, where it appears flattened. This situation gives the cell the appearance of a signet ring; hence, the term “signet cell” is often used in reference to an adipose cell. Slides (have unilocular fat): pancreatic c.t., mammary glad; skin.
C. Elastic connective tissue: in walls and inner lining layer of arteries.
D. Mucous connective tissue (primitive, embryonic variety): umbilical cord; mesenchyme.
E. Dense fibrous tissue. Classified according to the arrangement of fibers (regular and irregular) and type of fibers (elastin or collagen).
1) dense irregular: Hairy scalp (1) (2), Note clumpy, dense collections of collagen fibers in dermis; Spleen.
2) dense regular: Tendon. Note parallel bundles of fiber; be careful to distinguish from skeletal muscle on this slide!
II. Cartilage
A. Hyaline Cartilage. This tissue can be recognized by the presence of round, encapsulated lacunae, containing cells (chondrocytes) shrunken away from the walls of the lacunae. The cartilage is identifiable as of the hyaline variety by its homogenous matrix, devoid of visible fibrous structures. Slides: brochus; Hyaline Cartilage.
B. Elastic Cartilage. This variety is characterized by a meshwork of elastic fibers embedded in the matrix. Observe lacunae and chondrocytes. Slide: epiglottis; Elastic Cartilage.
C. Fibrocartilage. Observe collagenous fiber meshwork within cartilage matrix. Note linear arrangement of lacunae. Slide: Fibrocartilage.
III. Bone
A. Primary Spongy Bone. This is the first bone formed during development.
- Note trabeculae (network of bony plates) interspersed with marrow spaces.
- Note lacunae, which contain osteocytes; osteoblasts (bone forming cells at edges of osteoid); and osteoclasts (multinucleate giant cells that resorb bony matrix).
Slides: Tooth developing 1 ; Tooth developing 2 .
Developing bone 1; Developing bone 2. Note growth plate zones, details of endochondral ossification.
B. Secondary Compact Bone. This is remodeled from 1 degree spongy bone and organized into Haversian systems. Each Haversian system consists of concentric lamellae of bone surrounding a central Haversian canal. These are connected to the marrow cavity and to external bone surface by Volkmann's canals. Haversian and Volkmann's canals are the passageways for blood vessels.
- Note the lacunae and the canaliculi within the lamellae of the Haversian systems. Slide: dry bone - ground.
- Note components of Haversian systems in the jawbone area.
Smooth Muscle - Note arrangement of fibers (cross-sectional view, longitudinal view, oblique view) in the following organs:
hairy scalp.-> Note the relationship of muscle layers to connective tissue and epithelium.
-> Find the arector pili muscles near bases of hair follicles in slide of
-> Observe (in cross sections of smooth muscle) the centrally disposed nuclei in the fibers.al sections.
Skeletal Muscle - Examine cross sections and longitudinal sections.-> Note cross-striations (visible in long and oblique views).
-> Note peripherally disposed nuclei in cross-sectioned fibers; compare this arrangement with smooth muscle nuclei.
-> Examine the slides of the Tongue, Circumvallate: (1) (2), Fungiform: (3). Find the intrinsic muscle and observe its appearance in different areas within the tongue.
Cardiac Muscle
-> Find subendocardial Purkinje fibers. These are specialized conduction cells. Compare their appearance (larger, paler staining) with normal cardiac muscle.
Spinal cord - Slide: (1), (2), (3), (4). Note locations of gray and white matter.
- Find large motor nerve cell bodies in the anterior gray horn regions.
- Find nerve cell bodies and axons in the dorsal root ganglion.
Cerebellum - Slide: (1), (2), (3)
Cerebrum - Slide: (1), (2), (3)
Blood Smear. Slides - (1), (2)
Note the typical size and appearance of erythrocytes. These are pale, enucleate (means non-nucleated) cells, about 7.6 u in diameter.
-> Try to locate the various other cells and formed elements:
Leukocytes (granular):
a) Neutrophils - predominant type of polymorphonuclear leukocyte. Nuclei have several connected lobules, and discrete granules are scattered in the cytoplasm.
b) Eosinophils - distinct from neutrophils due to cytoplasmic granules staining bright orange-pink; nuclei have two irregular lobes.
c) Basophils (you must hunt for these!) - cytoplasmic granules stain deep purple.
Leukocytes (agranluar): lack chromatophilic cytoplasmic granules.
a) Lymphocytes - round, deep-staining nucleus, almost fills cytoplasm in small lymphocytes. Others (when stimulated) range in size from medium to large, the latter almost twice the size of an erythrocyte.
b) Monocyte - large cells (comparable in size to granular leukocytes) with typcial dark-staining nuclei. Nuclei appear slightly indented or markedly horseshoe-shaped. Cytoplasm may have a bluish, splotchy tinge.
Platelets: tiny fragments, usually found in clusters. Refer to atlas and text for photo of their ultrastructure.
Bone Marrow. Slide: (1), (2) Note adipose cells among hemopoietic tissue.
Artery; Aorta. Note typical layers.
Also, note presence of internal and external elastic laminae.
Arterioles, Venules & Capillaries
- Tunica intima - endothelium supported by loose connective tissue and some elastin and collagen.
- Tunica media - circular smooth muscle layer (thinner than in arteries)
- Tunica adventitia - loose connective tissue layer.
Examine the Lymph node.
- Distinguish the cortex, characterized by clusters of lymph nodules (alternatively called lymph follicles) with germinal centers.
- Contrast with the medulla, which features medullary cords of lymphocytes and sinuses.
Nodes are encapsulated by a connective tissue sheath, which is pierced at the hilum by efferent lymphatic vessels, nerves and blood vessels.
-> In the connective tissue of the capsule, note endothelium-lined afferent lymphatics, which may contain valves.
- A lymphatic organ distinct from lymph nodes by the absence of a surface connective tissue capsule. Tonsil surface is covered instead by stratified squamous epithelium. The surface epithelium is invaginated into the organ as crypts. Within the tonsil are lymphatic nodules embedded in reticular connective tissue. Base of tonsil consists of dense band connective tissue, which helps create a barrier to underlying tissues of oral cavity and pharynx. -
- Note the germinal centers which contain activated B lymphocytes. T lymphocytes are situated in the paracortical areas.
- The stroma of cortical nodules is formed by an abundance of reticular connective tissue.
Note numerous lymphatic nodules (with germinal centers), which span the lamina propria and submucosa of this G.I. tract appendage.
Thymus. Slide: (1), (2) - This is an encapsulated organ, divided into lobules by trabeculae of connective tissue. Each lobule consists of cortical lymphocytes (which kind?) and a medullary region with fewer cells. The medulla contains Hassall's corpuscles. The latter are composed of concentrically arranged epithelial reticular cells with a degenerating center. What are the functions of epithelial reticular cells? Where do they come from?Spleen. Slide: (1), (2) -called white pulp. Each lymphatic (or splenic) nodule bears a “central” artery, branching from trabecular arteries, and surrounded by the PALS (PeriArterial Lymphatic Sheath). (PALS are ocnsidered part of the white pulp). Interspersed among the trabeculae and white pulp are venous sinuses and splenic cords (Cords of Billroth), made of diffuse lymphatic tissue cords. Sinuses and cords are enmeshed in reticular connective tissue and are known collectively as red pulp.
MALT and GALT (Mucosa - or Gut- Associated Lymph Tissue) - These terms refer to unencapsulated lymph nodules located within loose connective tissue regions of other organs. When they appear in the mucosal CT, they are termed MALT. If they are found in the mucosa or submucosa CT of the gut, they are termed GALT (so you see, MALT can also be GALT, and vv).
Developing Tooth. Slides: (1), (2), (3) - Note the bony socket or alveolus, with its developing too.
Adult tooth (1), (2) Observe areas of dentin, root canal, pulp cavity and cememtum. enamel is NOT visible on this slide, since it is descarded during preparation of the specimen.
Tongue - Note surface epitheleum (stratified squamous), arranged in some regions as papillae. There are filiform, fungiform, and circumvallate papillae. Taste buds, which bear speacial chemoreceoptors, are especially evident in the circumvallate papillae.
Esophagus - Identify the tissue layers typical of the digestive tract:
- Mucosa (epithelium, lamina propria and muscularis mucosa),
- Submucosa,
- Muscularis externa, and
- Adventitial connective tissue (lacks a mesothelial covering).
- Observe stratified squamous epithelial lining.
- In the connective tissue, note any (mucous) esophageal glands, and their distribution.
- In the muscularis externa, observe the inner circular and outer longitudinal layers of muscle. Is the muscle here striated or smooth? What does that tell you about the portionof esophagus from which this section was taken?
- Note vessels and nerves in the adventitia, if present on your slide.
-> At the cardio-esophageal junction, note the stratified squamous epithelium on the esophageal side and the simple columnar epithelium on the gastric side. Note the gastric pits and glands and their relationship with the connective tissue lamina and inner muscularis.
Stomach - Slide: (1), (2), (3) Distinguish between the mucosa, submucosa, external muscularis, and serosa (serosa = outer loose C.T. plus a mesothelial layer, which is usually removed during slide preparation).
- In the mucosa, observe the epithelium, and is relations to the gastric pits; the lamina propria in which the glands are embedded, and the inner smooth muscle layer.
- In the submucosa, note absence of glands; abundance of vessels and nerves. The external muscle coat is composed of smooth muscle in three layers: oblique, circular, and longitudinal. These may appear enmeshed and may be difficult to distinguish as separate layers.
- Under higher power, study the gastric glands. Observe their epithelium and their depth.
- Identify three types of glandular epithelial cells forming the walls of the glands: mucous neck cells, chief (zymogen) cells, and parietal cells. What other cells are present though not easy to identify here in the epithelium?
- Compare gastric glands in cardia, fundic, and pyloric areas of the stomach.
Duodenum and Jejunum
- Observe that the lining of the small intestine (on the gross level) is thrown into a series of regular folds, the plicae (especially in the jejunum). This is arrangement is best seen at lowest magnification.
- Observe the mucosa, which is characterized by villi. These are fingerlike epithelial-covered projections of the lamina with smooth muscle, into the intestinal lumen. The cells covering villi are manly absorptive cells, and feature microvilli (brush border; check this at higher magnification.)
- Invaginating into the mucosa are intestinal glands called crypts. Note the cell varieties lining the crypts: goblet cells, argentaffin (i.e., enteroendocrine cells, which you cannot really distinguish these unless special silver stains are used!) and Paneth cells at the base.
- In the mucosa and submucosa, observe the amount, distribution and nature of lymphatic tissue. Epithelial areas covering lymph nodules (GALT) include M-cells, but do not expect to identify these.
-> What is the function of M (microfold) cells?
-> Be sure you understand the structural distinction between villi and intestinal crypts.
- Observe the layers and general histology.
- Observe duodenal glands of Brunner (mucous glands in submucosa); these are characteristic of the duodenum region only! (What do they produce? Why?)
- Identify the four typical layers, noting
- Note the aggregates of lymph nodules in the connective tissue; these characteristic arrangements are called Peyer's patches, and are diagnostic of ileum. Ileal villi are stubbier, and feature more goblet cells, than villi in duodenum or jejunum.
a) the absence of villi and b) persistence of crypts . The simple columnar epithelial lining has an abundance of goblet cells.
- Compare with colon and small intestine.
- Note lymph nodules in theCT.
- Examine the external muscle coats, inner circular and the outer longitudinal layers. The outer layers are found not as a continuous coat, but are separated into longitudinal bundles, the taenia coli. (This is more of a gross, than histologic feature.)
- Note the change to stratified squamous epithelium in the anal region.
- Compare this junction, considering structure and function, with the esophageal-cardia region, and the gastro-duodenal region.
--> Also observe and compare digestive tract junctions: (1), (2)
- Observe Islets of Langerhans scattered through pancreatic tissue. What do they synthesize? Is the pancreas an exocrine or endocrine organ or both?
Gall Bladder - Observe lining of simple columnar epithelium. A layer of fibromuscular tissue (smooth muscle and elastic fibers) underlies the lamina propria. Surrounding this is a wide layer of loose connective tissue.
Liver - Slide: (1), (2), (3) Note general organization into hepatic lobules. Connective tissue comprises the interlobular septa, where the (interlobular) branches of the portal vein, hepatic artery and bile duct are found as triads.
- In the center of each lobule, note the central vein.
- Under higher power, observe the plates of hepatic cells with sinusoids running among them. (Each lobule is bordered by a limiting layer of hepatic cells.) The sinusoids, lined partially with Kupffer cells of the reticuloendothelial system, communicate with the central vein.
- Running among the plates of hepatic cells are bile canaliculi. Much of the hepatic stroma is supported by reticular connective tissue.
Salivary Glands - How are their secretions conveyed to target organ (the oral cavity)? What is the nature of the nerve supply? Review duct system serving these glands. Note striated ducts that are diagnostic features.
Sublingual -Acini are mostly mucous. Seromucous variety bear serous demilunes hugging mucous acinus. Submaxillary -Acini are mixed: serous, mucous, and seromucous. -Acini are mostly serous.Distinguish among these glands:
Upper Respiratory Region
Epiglottis - Identify oral and laryngeal surfaces; type of cartilage and connective tissue.
Trachea - Slide: (1) (2) - Note cartilage. (What kind?) On cross-section, note (if present) the smooth muscle forming the posterior wall.
- Observe connective tissue area internal to the cartilage. What other structures/cells can you identify in the loose connective tissues?
- Observe the adventitial layer external to the cartilage ring, containing fat, nerves, vessels and possible lymph nodes.
Lower Respiratory Region
Lung - Slide: (1), (2) Under low power, observe general architecture.
- Under high power, examine epithelium of a respiratory bronchiole (cuboidal). Is it ciliated?
- Note the change in epithelium as you go from respiratory bronchiole to alveolar duct, sac, and alveoli.
I. Kidney - Slide: (1)
(2) (3)
(4) (5)
(6)
-> Before beginning a study of histological sections of the urinary system, it is essential that the following gross anatomical structures and their interrelations be recalled: renal cortex, renal medulla, renal pyramids, minor calyces, major calyces, renal pelvis, and ureter.
The functional unit of the kidney, the nephron, is a complex and tortuous tubular structure that originates in the renal corpuscles in the cortex. After looping into the medulla, it ends by joining a collecting tubule within a medullary ray of the cortex.
- Identify the major parts of renal corpuscles and of nephrons using the following criteria:
a. Parietal wall of Bowman's capsule: a thin squamous epithelium enclosing an obvious space (space of Bowman).
b. Visceral wall of Bowman's capsule: this is a mass of podocytes with basophilic nuclei apposing Bowman’s Space. Note red blood cells within the endothelium of the glomerular capillaries. Consult your text concerning the fine structure of the glomerulus.
c. Proximal convoluted tubule (PCT) and straight portion of the loop of Henle: The cells of this cuboidal epithelium contain a single spherical nucleus and an eosinophilic cytoplasm. The luminal surface of PCT bears a prominent brush border.
d. Limbs of Henle's loop - descending and ascending: consists of a low cuboidal epithelium.
e. Thin portion of Henle's Loop: Epithelicum is squamous. Sections resemble capillaries, but lumen should NOT contain blood cells. Compare to nearby sections of vasa recta.
g. Macula densa and juxtaglomerular cells, forming JGA: the macular densa consists of a concentration of nuclei of the distal tubule as it contacts the vascular pole of a renal corpuscle between the afferent and efferent arterioles. The juxtaglomerular cells are specialized cells of the tunica media of the afferent arteriole.
collecting tubules and ducts. The epithelium varies from low cuboidal in the smallest tubules of the medullary rays to high columnar in the ducts of Bellini near the apex of the medulla. The borders between cells of collecting tubules are distinct and the cytoplasm is relatively clear.-> Identify
II. Ureter.
- In the mucosa, note the transitional epithelium (4-5 cells thick), the dense underlying connective tissue with its slender vascular papillae, and the loose, deeper connective tissue.
- In the muscularis, note the interlacing fasciculi of smooth muscle which form a thin, inner longitudinal layer, a thicker circular layer and, in the lower ureter, a thin, outer longitudinal layer.
III. Urinary Bladder - Slide: (1) (2) In the mucosa, observe the transitional epithelium, (5-6 cells thick), and its connective tissue similar to that of the ureter.
- In the muscularis, observe the intermingled layers of smooth muscle: inner longitudinal, middle circular and outer longitudinal.
- Compare distended and relaxed bladder areas.
IV. Urethra - Observe epithelium, which varies from transitional near bladder to stratified squamous near the external orifice. The lamina propria is rich in elastic fibers and vessels; some mucous glands may be present. The muscularis coat conissts of inner longitudinal and outer circular layers of smooth muscle.
Pituitary - Slide: (1) (2) (3) (4) (5) Distinguish the pars distalis (anterior), pars nervosa (posterior). Pars intermedia will be sandwiched in between.
- The thyroid gland consists of simple cuboidal epithelial-lined follicles containing highly acidophilic colloid. Surrounding follicles is sparse connective tissue; note that there are parafollicular (or C) cells, too. What do these C cells produce? What is the role of follicle cells and how are they regulated? What is the colloid and why is there so much of it?-> Under high power, observe cells of pars distalis: chromophobe cells (pale and small), chromophil alpha cells (acidophilic) and beta (basophilic) cells.
-> The pars nervosa contains nerve fibers and neuroglia. Sandwiched between these lobes is the pars intermedia, characterized by colloid-filled vesicles lined by simple cuboidal cells.
-> The pars tuberalis (may not be present, if section is a cross section!) is a continuation of the anterior and posterior lobes and represents the connecting stalk of the gland to the base of the brain (hypothalamus).
Parayhyroid - What is the relationship between the parathyroid and thyroid (anatomically) and developmentally? The parathyroid is copmosed mainly of plates of principal (chief) cells. Larger, pale oxyphil cells appear scattered among the principal cells. What product does this gland secrete? What cells are targeted by this product?
Adrenal - Slide: (1) (2) (3) Describe the anatomical relationship of the adrenals to the kidneys. These glands bear a connective tissue capsule that penetrates the parenchyma. The gland is composed of cortex and medulla.
-> The cortex features three regions. Most superficial is the zona glomerulosa, with clusters of cells. Deep to this region is the zona fasciculata, in which cells appear lined up as columns with capillaries running parallel. The deepest cortical layer is the zona reticularis, which consists of branching cords of cells; some cells contain a yellow pigment. What are the products of the adrenal cortex and their functions?
-> The core of the gland is medulla, composed of granular chromaffin cells. What are the products and functions of this region? Why can it be stated that the adrenal received a dual blood supply?
Pineal. Observe cords of pinealocytes and interstitial cells, with long, dark-staining nuclei. Aging diminishes the connective tissue stroma of this gland and promotes the formation of calciferous regions, "brain sand." Why has this gland been called the "third eye?"
Save these two for your study of the REPRODUCTIVE systems:
Testis. Observe the connective tissue forming interstices of the seminiferous tubules. Epitheloid cells located here (cells of Leydig) produce testosterone.
Ovary - Observe follicles with granulosa cells, and also theca interna and externa, regions which ultimately produce estrogen.
---> Observe corpus luteum, a transient endocrine structure that secretes progesterone and estrogen.
Understand the gross relations of the following structures:
Testis - Slide (1) (2) (3) Note the surrounding connective tissue capsule, the tunica albuginea, which is continuous with the supporting interstitial tissue of this organ.
--> Study the seminiferous tubules and distinguish the stages of spermatogenesis, using your knowledge of the process and is features. note Sertoli cells whenever possible.
- Note pseudostratified columnar epithelium surrounding an irregularly shaped, small lumen; supporting this layer is a lamina rich in fibers and a muscularis. The inner smooth muscle coat is longitudinal. Surrounding this is a highly vascularized adventitia. - A sac, whose walls bear complex primary and secondary folds formed by epithelium and supporting lamina. Surrounding the sac is a double muscular coat and adventitia. What is the relation between the organ and the urinary system? - Observe the prostatic glands scattered in a connective tissue interstitium characteristically rich in muscle, collagen and elastic fibers. These branched glands are lined with pseudostratified or columnar epithelium (variable). Prostatic tissue surrounds the prostatic urethra.
Penis - Slide (1) (2) (3) Transverse view demonstrates two dorsal corpora cavernosa and anteromedial corpus spongiosum, which contains the urethra. These bodies are separated by tunica albuginea (connective tissue) and are surrounded by the connective tissue of the dermis and by the epidermis. Each corpus bears muscular and fibrous trabeculae surrounding a mesh of cavernous veins.
Scan the active organ and note the following:
Fallopian Tubes - Slides: (1) (2) (3) Observe the highly irregular muscosa lined with simple siliated (why?) columnar cells and a loose vascular lamina; surrounding are smooth muscle coats. Compare the fibrial with more distel parts of the tube.
Uterus postmenstrual
or proliferative phase - Observe layers of wall:
- This phase involves thickening of endometrium
due to active secretion of glands, and interstitial fluid build-up. Glands have
hypertrophied (see many more secretions); coiled arteries are prominent through
endometrial region. Stratum functionalis now includes a superficial compact
zone beneath, with much glandular activity.
Placenta - Slide: (1) (2) (3) (4) Observe maternal portion, consisting of the stratum functionalis of the endometrium (decidua basalis), which is penetrated by anchoring villi [high mag villi in cross section]. Note decidual cells forming base of maternal side.
->The opposite surface is the fetal portion. Note simple cuboidal amniotic epithelium, with underlying chorionic plate. From this plate, chorionic villi penetrate down through the placenta into the decidua basalis. Intervillous spaces contain maternal blood; villi are covered with trophoblastic epithelium, with a core of embryonic connective tissue and fetal blood vessels.
Mammary Gland -
Note branched secretory glands arranged into lobules by dense interlobular connective tissue septa, with adipose. The secretory alveoli are embedded in loose "expansible" connective tissue. Alveoli are lined by low columnar epithelium.
Skin
Hairy Scalp - Slide (1) (2) Skin, pigmented and nonpigmented - Note epidermis (epithelial layer) and dermis (composed of papillary and reticular layers of connective tissue). Projections of fiber-filled connective tissue inot the epithelium are dermal papillae. Deep to this is a thick reticular layer of dense, irregular connective tissue. Underlying this are layers of adipose tissue (subcutaneous fat) and skeletal muscle.
Sweat Gland - Slide: (1) (2) Note apocrine sweat glands; compare with eccrine variety. how do these differ? From where in the body might this skin section have come?
Tongue -
circumvallate papillaeEye
- Observe:
- Sclera
- Choroid coat
- Retina (note: sensory retina versus pigmented (melanin-containing) layer that is subjacent to photoreceptors
- Macula lutea, also known as fovea (if present in section)
- Optic nerve (a.k.a. optic disc or optic papilla)
- Pigment cell layer,
- Rods and cones
- Outer plexiform layer,
- Inner nuclear (bipolar cell) layer
- Inner plexiform layer
- Ganglion cell layer
- Inner layer of nerve fibers
Ear
- Note crista ampullaris, and maculae.-> Compare crista (note cupola) with macula (note otoliths).
-> Cochlea - Note 3 ducts (or scalas)
-> Note vestibular and basilar membranes; tectorial membrane, stria vascularis, spiral ganglion, and components of the Organ of Corti (hair cells and supporting cells).
-> Look for maculae and/or cristae ampullaris.
