Retina: OPL Flashcards
What are the 2 synaptic layers in the retina?
- Outer plexiform layer
- Inner plexiform layer
What does the outer plexiform layer contain?
contains the synaptic endings of rods (spherules) and cones (pedicles)
-these synapse mainly with horizontal and bipolar cells
What is the rod synaptic ending?
- is smaller and spherical
- one invagination
- known as spherules
What is the cone synaptic ending?
- synaptic region of cone is quite big
- several invaginations
- known as pedicle
What is the main characterisitc of cone pedicle ?
-full of vesicles (vesicles of the neurotransmitter)
What does each pedicle contain?
- Each pedicle contains ca. 25 invaginations
- each of which is associated with a synaptic ribbon
- these synaptic ribbon are associated with the halo vesicle
- contains 3 synpases
- bigger than rods synaptic ending
What do the synaptic ribbon do?
that may serve to guide vesicles to their site of release
What is each invagination associated with?
-Each invagination is also associated with a ‘triad’
What is a triad?
3 post synaptic processes
What do the lateral elements of a triad are provided?
come from horizontal cells
What do the central elements of a triad are provided by?
the less deeply invaginating central element comes from a bipolar cell
What does a electron micrograph of a cone pedicle show?
invaginations (i.e2) and associated ‘triads’ (others are out of plane of section)
What does a cone pedicle make contact with?
- triads made up of 2 lateral elements from horizontal
cells and central element from bipolar cells
however not all post synaptic processes on pedicles are triads.
What are other post synaptic contacts that dont associate with cone pedicle?
There are about 500 superficial (non-invaginating) contacts which come from bipolar cells in each cone
What are the synapses in the triad of cone pedicles?
have horizontal cells and bipolar cells
and then superficial contact with bipolar cells