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Histology What to look for

Histology review Quiz = 40 pts • Some slides set up • Some pictures on the projector

Questions: • What kind of tissue? • General function? (e.g. absorption, protection) • Cells, fibers, ground? • An example of where would you find it?

Slides • Epithelial tissues (7 types, could be ANY of the examples provides) • Connective tissues (11 types, ANY example that we looked at) • Integument and accessory structures

Epithelial tissue

Let’s review….

Simple cuboidal epithelium • lining a tubule (longitudinal cut). Some of the cell boundaries between "blocks" or "cubes" here are quite distinct.

Simple Cuboidal • Covers surface of ovary, lines kidney tubules and small ducts of glands (thyroid and pancreas)

Tubule - cross section simple cuboidal

Another example - kidney

Type?

Simple squamous epithelium • High power view of endothelial cells lining a small blood vessel cut in cross-section. (You see just the nuclei - the cytoplasm between them is extremely flat.) Endothelium = the simple squamous epithelium lining blood vessels.

Simple squamous epithelium

Kidney

Superficial view (squamous)

Type?

Simple columnar • Another example – intestine, with goblet

Intestinal lining

Yet another

Type?

Pseudostratified ciliated columnar epithelium Trachea. Nuclei are at different levels. All cells touch the basement membrane, but only the taller cells reach the lumen. The cilia are longer and less regular than the microvilli of a striated border.

Pseudostratified Columnar Epithelium • Look like multiple layers • Trachea

Figure 4–5b

Another example

Cilia – surface view

Type?

Bladder Low power

Transitional Epithelium • Tolerates stretching • Appearance changes (stratified to simple) • Urinary bladder

Figure 4–4c

Type?

Stratified Squamous Epithelium

Figure 4–3b

Example

Example

Type?

Type?

Stratified Cuboidal Epithelium • Sweat gland ducts

Figure 4–4b

Type?

Stratified Columnar Epithelium • Rare • Salivary gland duct

Figure 4–5c

Connective tissue

Connective tissues Connective tissue proper • Loose connective tissue – Areolar – Adipose – Reticular • Dense connective tissue – Dense regular – Dense irregular – Elastic tissue

Fluid CT –Blood Supporting CTs •Cartilage –Hyaline cartilage –Elastic cartilage –Fibrocartilage • Bone

Areolar tissue • A loose CTP

Areolar

Areolar: what to look for • • • •

Fibroblasts Collagen fibers Elastic fibers Mast cells and macrophages

• Found? Throughout body, under dermis, divides skin from underlying tissues

Fibroblasts • Resting fibroblasts typically have so little cytoplasm that the cells appear, by light microscopy, as "naked" nuclei

Fibroblast

Adipose tissue • Another lose CTP (note nucleus)

Adipose: what to look for • Lots of cytoplasm • Slim nuclei pushed off the side • Found? You know where

Reticular tissue • The third type of loose CTP

Reticular tissue

Reticular: what to look for • Reticular fibers (network) • Found? Internal framework in many sort organs (liver, spleen) supporting the parenchyma

Dense CTP • Dense regular – strength in one direction • Dense irregular – strength in all directions • Elastic tissue - pliable

Dense regular

Dense regular: what to look for • Thick parallel bundles of collagen • Small fibroblasts in between bundles • Found? Tendons, ligaments, deep fascia.

Dense irregular

More dense irregular

Dense irregular: what to look for • Mesh of collagen fibers (irregular looking) • Interspersed fibroblasts • Found? Dermis of skin, periosteum, perichondrium

Elastic tissue

Elastic tissue: what to look for • Elastic fibers (instead of collagen fibers) in large bundles • Fibroblasts • Found? Between vertebrae, in blood vessel walls (underneath endothelium)

Fluid CT • Blood

Blood: what to look for • RBCs • White blood cells (darker): monocytes, lymphocytes, granulocytes • Platelets

Supportive CT • Cartilage – gelatinous, padding – Hyaline cartilage – Elastic cartilage – Fibrocartilage

Hyaline cartilage • Glasslike because fibers not visible

More hyaline • There are collagenous and elastic fibers lying in the cartilage matrix but they are invisible because their “refractive index” is the same as that of the matrix (like cornea)

More hyaline

Hyaline cartilage

Hyaline • Hyaline cartilage (lavender matrix), with perichondrium (pink) outside it. The latter is a dense regular collagenous CT. Cartilage cells = chondrocytes, and they are lying in the lacunae.

Hyaline cart.: what to look for • Perichondrium • Chondroblasts (make the matrix fibers and ground) • Chondrocytes and lacunae • Where? Most joints, nasal septum

Elastic cartilage

Elastic cart: what to look for • • • •

Many elastic fibers in matrix Perichondrium Chondroblasts Chondrocytes in lacunae

Fibrocartilage

Fibrocartilage: what to look for • Irregular, wispy collagen fibers • Chondrocytes, often stacked up • Found? Intervertabral discs of spine, pads in knee joint

Supportive CT: Bone

• Detail of lacuna, showing radiating canaliculi. Tissue fluid from the capillaries and connective tissue of the Haversian canal can seep through these spaces and channels, bringing nutrients to the stellate osteocytes residing there.

Bone: what to look for • • • • • •

Osteon (whole circular structure) Concentric lamellae (of matrix) Central canal (at center of lamellae) Osteoblasts Osteocytes in lacunae Canaliculi

Found? Bones!

Integument

Epidermis and dermis

Epidermis What to look for: • Usually darkest between stratum germinativum and stratum granulosm (granulosm often a dark meandering line) • Keratinized cells often lift off the section • Melanocytes just below basal lamina

Dermis: Papillary vs. Reticular layer

What to look for: • Papillary layer – has ridges – is areolar – Just under basal lamina

• Reticular layer – much thicker – Dense irregular CT

Again

Merocrine sweat glands

Merocrine sweat gland • What to look for: – Found in most skin – Coiled, tubular – Small lumens in cross section – Have duct that goes all the way to the epidermal surface and ends in sweat pore – Smaller than apocrine, don’t extend as deep into dermis

Apocrine sweat gland

Apocrine sweat gland What to look for: • Associated with hair follicle • Only in nipples, groin, armpit • Large lumens • Deeper in dermis than merocrine

Hair with sebaceous glands and arrector pilli

Hair What to look for: • Follicles are rarely complete • Can often see root, papilla (at base, wher hair grows) • Arrector pilli muscle at an angle • Associated glands (which are?)

Sebaceous glands

Sebaceous glands What to look for: • Associated with hair follicle • Found most everywhere hair follicles are found in skin • Look like cauliflower (maybe?)

Sebaceous follicle

Sebaceous follicle What to look for: • Also look like cauliflower • Found on face and trunk only • NOT associated with hair follicle • Have duct that opens onto skin surface