Abstract
Purpose::
To determine whether diffuse bipolar types in primate retinas differ with respect to their contacts with short wavelength-sensitive (S-) cones.
Methods::
Bipolar cells in marmoset and macaque retinas were labelled with antibodies to the glutamate transporter Glt-1 (OFF bipolar cells), or antibodies to the alpha subunit of the Go protein (ON bipolar cells). Two types of diffuse ON bipolar cells, DB4 and DB6 were identified with antibodies to protein kinase Cα and CD15, respectively. Cone pedicles were labelled either with peanut agglutinin coupled to fluorescein or with antibodies to the ribbon protein, C-terminus binding protein 2.
Results::
Immunoreactivity for Glt-1 (OFF bipolar cells) is reduced at S-cones in comparison to medium/long wavelength-sensitive (M/L-) cones. Immunoreactivity for Goα (ON bipolar cells) is comparable at all cone types. Nearly all M/L-cone pedicles contact the ON diffuse bipolar types DB4 and DB6, but only between 60% and 75% of the S-cone pedicles make contact. Furthermore, the number of dendritic tips of DB4 and DB6 cells at S-cone pedicles is lower than that at M/L-cone pedicles.
Conclusions::
These results suggest that there is a bias in the S-cone connectivity of diffuse bipolar cells in primate retina.
Keywords: bipolar cells • retina: distal (photoreceptors, horizontal cells, bipolar cells) • retinal connections, networks, circuitry