Histology Lab Terms Flashcards
Epidermis
the most superficial layer of skin comprised of stratified squamous orthokeratinized epithelium. Separated from the underlying dermis y a very thin basement membrane
Stratified Squamous orthokeratinized epithelium
multilayered tissue wherein the most superficial livings cells are flattened and then covered by a noncellular layer of keratin
Keratinocyte
most common cell type in the epidermis. Creates morphological epidermal strata as it moves upward through the epithelium. After cell death the keratin cytoskeletal elements remain as a protective covering layer on the surface of the integument
Stratum Basale
single layer of epidermal cells located immediately above the basement membrane. Anchors the epithelium and is the location of keratinocyte mitotic activity
Stratum Spinosus
variability multilayered stratum immediately above the stratum basal. Due to the shrinkage artifact, strong desmosome cell junctions are visible at high mag as very fine linear projections perpendicular to the keratinocyte surface
Desmosome
Node of bizzozero
very strong, spot-weld type junction incorporating both intracellular proteins and extracellular proteins to provide exceptional mechanical adhesion b.w keratinocytes. Due to shrinkage artifact, appear as thin linear projections extending perpindicullarily from the surface of the keratinocytes in the stratum spinosus
Stratum Granulosum
the most superficial layer of keratinocytes still living at the time of tissue preparation. These squamous shaped cells are only a few layers think and have a granular appearance due to the presence of keratohyaline
Stratum Lucidum
usually a thin light stained layer of noncellular sheets of keratin/keratinohyalin located immediately above the stratum granulosum, absent in hairy skin
Stratum Corneum
the bulk of non-cellular sheets of keratin/keratinohyaline located most superficially in the epidermis. This layer is thin in hairy skin and think in glabrous skin
Keratin
the intermediate filament cytoskeleton protein present in epithelial tissues. Incorporated into desmosomes and visible as sheets in stratum lucid and stratum corneum
Clear Cell of the epidermis
Melanocytes, Langerhans Cell, Merkel Cells
synthesizes and secretes pigment which is then picked up and stored by keratinocytes. Appears as a clear staining cell in the stratum basale
Rete Peg
extension of the epidermal stratifies squamous orthokeratinized epithelium down towards the underlying dermis. Contributes to the overall adhesion between the dermis and epidermis
Basement Membrane
very thin, non cellular sheet of glycoproteins located at the epithelial tissue interface. Serves as an anchor and filter for the epithelial compartment. Although not directly visible, its location can be identified by the dramatic morphological change present at the epidermal/dermal layer
Dermis
intermediate layer of skin comprised primarily of dense irregular connective tissue. This layer provides physical and physiological support to the overlying epidermis and is also location for the glands and many of neuromuscular elements of integument
Dense Irregular Connective Tissue
comprised of thick or coarse Type I collagen fibbers bundle in a disorganized or irregular pattern. Many cell types will likely be present with the most common being fibroblasts or fibrocytes
Fibroblast/Fibroblast
cell responsible for synthesis of the noncellular components of various general connective tissues. Although the cytoplasm of this cel is often not directly visible, the nucleus is visible as small, flattened, heterochromatic and either oval or round. This most common cell type in the dermis
Dermal Papilla
projection of the dermal dense irregular connective tissue up toward the overlying epidermis. Contributes to the overall adhesion between the dermis and epidermis.
Papillary Dermis
relatively thin, uppermost region of the dermis inclusive of the dermal papillae and the intervening segments of dermis deep to the rate pegs. Comprised of dense CT usually with no clear demarcation between papillary and reticular dermis
Hypodermis
deepest layer of the integument comprised primarily of adipose. Equivalent to superficial fascia in gross anatomy
Adipose
special type of CT comprised almost entirely of large cells bound to each other by very thing strands of Type I collagen and packaged into bundles of cells by thin seems of dense irregular CT
Seat Glands
tubular expansion of the epithelium away from the epidermis usually to a point pairly deep to the reticular dermis. The secretory portion of this tubular gland is coiled upon itself deep within the dense irregular CT of reticular dermis and the loops this coiled gland are entwined by loose CT. The excretory duct of this tubular gland spirals up through the dermis and epidermis and opens via a pore at the surface. As this gland is unbranched along its entirety it is known as a simple tubular gland
Loose Connective Tissue
comprised of very thin, delicate collagen fibbers in a disorganized or irregular pattern. When associated with sweat glands the only cell type likely to be seen is fibroblast/fibrocyte
Hair Follicle
large invagination of the epidermal epithelial cells deep into the reticular dermis. The base of the follicle, knows as the bulb, is the ovation for synthesis of the noncellular hair shaft. The root sheath refers to the cells surrounding the hair shaft and extending from the bulb to the epidermis
Arrector Pili muscle
a relatively narrow slip of smooth muscle originating from the side of the root sheath and angling some distance into the surrounding dermis. When contracted, this muscle causes the follicle to become slightly more erect and produces a slight bulce in the integument surface
Sebaceous Gland
globular cluster of densely packed, pale staining cells extending from the side of the hair follicle. Each cluster of cells typically has its own duct leading into the follicle hence the gland is known as a simple acinar gland
Meissner’s Corpuscle
relatively small sensory receptor for light touch. Located within the dermal papilla and has appearance akin to a cocoon or giant mitochondria
Pacinian Corpuscle
relatively large sensory receptor for deep pressure. Located near the dermal/hypodermal interface and has appearance akin to a topographical map or a sagitally sectioned onion
Dense Regular CT
comprised of thick or coarse Type I collagen fibbers bundles in a highly organized and parallel pattern. The only likely cell type present here are fibroblast/fibrocyte.
Collagen
most common fibrous extracellular matrix protein found in most CT. Variable in thickness, often wavy and usually stains pink
Hyaline Cartilage
slide specimen taken from trachea. The matrix appears smooth because the Type II collagen present is too thin to be resolved with light microscopy. The matrix is produced and maintained by chondroblasts/chondrocytes. No other cell types or structures are located in cartilage. This tissue is surrounded by a transitional perichondrium which blends characteristics of the cartilage with the adjacent general CT
Lacuna
the space in the extracellular matrix where a chondrocyte was located. Most visible as a hole in the cartilage matrix when the cell is absent
Chondrocyte
relatively large, round cell located withith the matrix lacuna of any of the three types of cartilage. Responsible for maintaining cartilage matrix and, as such, is relatively inactive
Isogenous Group
a cluster of chondrocytes and their associated lacunae. Indicitive of rapid mitotic cell division and/or slowing of interstitial growth. Each of the cells within the group are descendants of a single parental chondrocyte
Chondroblast
relatively small, ovoid cell located in the chondrogenic perichondrium of hyaline and elastic cartilage. Primarily responsible for new cartilage matrix deposition and, as such, is relatively active
Chondrogenic Perichondrium
the inner portion of the perichondrium containing chondroblasts and a matrix very similar to the cartilage. Site for appositional growth.
Fibrous Perichondrium
the outer portion of the perichondrium containing fibroblasts and a matrix very similar to those surrounding tissues
Perichondrium
general term for the transitional tissue surrounding hyaline and elastic cartilage. Inclusive of both the chondrogenic and fibrous layers. Contains the cartilage vascular supply and is the source for much of the cartilage growth and repair
Epiphysis
either end of a long bone. Can be made of hyaline cartilage. The hyaline cartilage is being replaced by bone via a mechanism known as endochondral ossification
Diaphysis
the shaft of long bone. The marrow cavity is surrounded by a relatively think shell of compact bone. Traversing through the marrow cavity are small bony spicules collectively known as spongy bone
Marrow Cavity
central region of bone housing the hemtopoietuc cells and spongy bone.
Compact and Cortical Bone
relatively thick shell of bone forming the periphery of the diaphysis. Contains osteocyts in lacunae and is lined internally by endosteum and externally by periosteum,
Spongy or Cancellous Bone
collection of relatively thin bony spicules traversing thru the marrow cavity. At a later time, when endochondral ossification advances to completion, this bony pattern will occupy the entire epiphysis. Usually appears as bony islands scattered thru the diaphysis
Endosteum
layers of cells lining the inner surface of the compact bone and eventually the spongy bone surfaces as well. This layer of cells provides for growth and remodelling of the compact bone inwardly towards the marrow cavity
Periosteum
transitional layer of tissue covering the outer surface of the compact bone. Note its absence on the articular surface of the epiphysis
Osteogenic Periosteum
the inner portion go the periosteum primarily containing osteoblasts. This layer of cells provides for growth and remodelling of the compact bone outwardly
Fibrous Periosteum
the outer portion of the periosteum primarily containing fibroblasts and general CT matrix. Typically blends with tissue surrounding the bone
Osteocye
responsible for the maintenance of existing bone matrix. Limited in location to lacunae within compact or spongy bone
Osteoclast
responsible for the resorption of existing bone matrix. Comparitively large, multinucleate cell located on the resorbable surface including endosteum and osteogenic periosteum
Osteoblast
responsible for the deposition of new bone bone matrix. Has a smack, flattened oval, heterochromatic nucleus and is located on a growable surface including endosteum and osteogenic periosteum. Also present on developing bony spicules in the zone of ossification.
