Integument Flashcards
exoskeleton/integument
the outer covering of an insect
Epidermis/basement membrane
the only living portion of the integument. The innermost layer of the integument that is secreted by hemocytes, forming a continuous layer of connective tissue that separates the body cavity from the integument.
Dermal gland
A modified epidermal cell that produces the cement layer, as well as defensive secretions and pheromones
Oenocytes
A specialized hemocyte that usually resides between the basement membrane and the epidermal cells. They synthesize wax and possible ecdysteroids
Epicuticle
Top layer of the cuticle, consists of proteins, lipids, waxes, cements, minerals and others. NO chitin
Procuticle
The undifferentiated chitinous cuticle that develops into the endocuticle and exocuticle. secreted at tips of microvilli as stacks of laminae, consists mostly of chitin and protein (newly forming cuticle- lays down later layers)
Exocuticle
Layer between the epicuticle and mesocuticle. Contains both chitin and protein. Highly sclerotized
What is the order of the integument from outside to inside
- Epicuticle
- Cuticulin
- Exocuticle
- Mesocuticle
- Endocuticle
What is the order of the integument from outside to inside
- Epicuticle
- Cuticulin
- Exocuticle
- Mesocuticle
- Endocuticle
- Epidermis/basement membrane
Mesocuticle
less sclerotized layer between the exo- and endocuticle
Endocuticle
contains both chitin and protein, but is soft and flexible. Digested between apolysis and molt.
Procuticle
the combined name for Exocuticle, mesocuticle and endocuticle
Chitin
A polysaccharide consisting of linked N-acetyl-glucosamine residues. Chitin is insoluble in water, dilute alkali, alcohol, and organic solvents, but soluble in concentrated acids and hot alkali solutions. The chains of chitin are associated with protein, providing a framework for the stabilization of the cuticular proteins.
Chitin microfibrils
alpha, beta, and gamma chitin, each have different orientation, different proteins
Precursor for Chitin
Trehalose or glycogen to GLUCOSE
How is chitin made?
Chitin synthase loaded vesicles move from the trans-golgi to the apical region of the epithelial cells and fuse with the plasma membrane.
Apodeme
projection of the cuticle into body (internal skeleton) = endoskeleton; muscle attachment
Envelope
Bursicon
A hormone that mediates cuticular sclerotization
Chitosan
Chitin treated with concentrated alkali at high temperatures is deacetylated to yield chitosan which produces a characteristic violet color with iodine as an indication that chitin was once present
Ecdysis
the process of shedding the old cuticle at the end of molting
Cuticle enzymes
- Chitin deacetylases
2. Diphenoloxidase/tyrosinase
Resilin
A rubber-like protein enriched in tendon/ligaments
hemiadherens junctions
A form of cellular attachment to extracellular matrices or “tendon” cell
Pore Canals/Pit glands
Small channels that extend from epidermal cells through the cuticle up to the epicuticle and carry substances such as waxes.
Apolysis
the separation of the epidermis from the overlying cuticle. Marks the beginning of the molt
molting gel
An enzyme produced by epidermal cells that digests the old endocuticle during the molting process. It is first secreted in an inactive form, and activated once the new cuticle begins to be formed.
Cuticulin
a layer of the epicuticular envelope. Also called the outer epicuticle, the epicuticle is deposited on its inner surface.
cement layer
The outermost layer of the epicuticle, produced by dermal glands and consisting of a shellac-like coating. The cement layer that seals the wax layer and provides protection from physical abrasion
envelope
assembly at plasma membrane surface, made of chitin and protein
What chews up the old cuticle?
Chitinase
Inka cells secrete what?
Ecdysis triggering hormone ETH
VM cells secrete what?
Eclosion hormone
Inka cells are located where?
located in the tracheal trunks and associated with spiracles
Eclosion hormone
A peptide that initiates the shedding of the old cuticle at then end at the molt or emergence of the pupa. Made in the VM neurosecretory cells of the brain
Blastema
A population of dedifferentiated proliferating cells that forms at the distal top of the leg stump.
