Invaginating Blue Bipolar
Input | Output | Function | Morphology | Array | Comp. Model | Location | subclass | Syn Receptor | Transmitters | Immunocytochemistry | Nomenclature
By a large majority, this cell is encountered as an On-center variety. Only Kolb et al '92 reports ever seeing a putative off-center variety.
Kouyama & Marshak describe this cell as characteristically providing the central element of the dendritic triad at the blue cone pedicles. They also describe unknown dendritic elements which form "triad-associated flat contacts". Since, as they acknowledge, these are likely to be other bipolar types, I refer to this type as the invaginating blue bipolar.
Back to list of cells
- Postsynaptic connections (Input)
- Presynaptic connections (Output)
- Rodieck 1988 points out that the blue bipolars are described as having axons terminate in the *inner* half of the IPL while the blue ganglion cells De Monasterio stained had dendritic fields that ramified in the *outer* part of the IPL.
- Bistratified On Blue Ganglion cell
- Off Midget Amacrine cell
- Kolb et al 1992
- Axon terminal arborizing in stratum 5 of the IPL
- "two sturdier dendrites converging on the same cone and finer, wispy branches ending either on another cone or in the neuropil of the OPL."
- "the axon terminal.... widely ramifying varicose structure ending in stratum 5 of the IPL"
- Kouyama and Marshak (1992)
- A single dendrite which runs vertically through the INL and branched upon reaching the OPL. Diameter of at least 2 um.
- In periphery, somata sometimes extended into the OPL where 2 or more dendrites branched directly from the soma. After this dendrites rarely branched and ranged from .2um to 2um in diameter.
- In periphery: dendrites made 1-4 major dendrites, dendrites length 10-50 um, axons had 1-3 branches ranging from 5-35 um in length and were typically shorter than the dendrites.
- Dendrites usually avoided the closest cone, but reached cone pedicles 10-50 um from the soma.
- Upon reaching the target cone pedicle, the dendrites tapered to less than 1 um in diameter and divided.
- Final invaginating dendrites varied from .1um to um in diameter and deeply invaginated the cone pedicle.
- Somas 7-9 um in diameter in 1st or 2nd row of INL
- Axons less than 1 um in diameter and didn't ramify in the strata where similarly stained amacrines were found.
- Axons branched 75%-95% depth in IPL ~ 5th stratum
- Central retina
- Their technique didn't work to well in the fovea because the dye didn't disperse to well. In other words the fovea was to tightly packed.
- Somas were mostly in the outer half of the INL. They were smaller than those in the periphery and more densly packed.
- The axon reached stratum 5 of the IPL where they had expansions similar to those of peripheral blue bipolars.
- A single main dendrite which was longer than the peripheral dendrite since the INL was thicker.
- Typically the dendrite ended at a single cone with several terminal bifurcations and swellings.
- Some bipolars did contact 2 cones.
- Dendrites were oriented toward the fovea and axons toward the periphery.
- Soma diameters were 6.3 +- .4 um (mean+-sd)
- Eccentricity changes
- Fitted line to soma diameter data
- Temporal: Y = .064X + 6.15 (R2 = .938)
- Nasal: Y = .035X + 6.34 (R2 = .989)
- X : eccentricity in degrees
- Y : diameter in um
- As many as 4 bipolars contacted a single cone.
- As many as 3 cones were contacted by a single bipolar.
- On average 1.84 +- .7 bipolars contacted each cone
- On average 1.22 +- .56 cones provided input to a single bipolar
- Electron Microscopy
- 2 um from the target pedicle, the dendrite usually bifurcated several times forming terminal specializations.
- The dendrite ends were separated from the ribbon synapse by about .1 um by lateral dendrites from other cells.
- Both Koyama and Marshak and Mariani noted dendrites which taper and end without any specialization in the middle of the OPL. Some cells had exclusively these dendrites. K & M suggest that this resulted from degeneration of blue cones and not from contacts with other cone types.
- Array characteristics
- bipolar cells/blue cones = 1.4+-.2 in ventral retina
- 140 bipolars/degree2 in central periphery
- ~5 @ 60 degrees temporally
- ~35 @ 60 degrees nasally
- Density in nasal half was consistently higher than temporal half.
- Compartmental Model Characteristics
- Synapse types
- Synapse Receptors
- Antisera that recognize glycine-extended cholecystokinin (CCK) precursors
Back to general retina list
visit(s) to this page.
© 1995 Lance Hahn(firstname.lastname@example.org)