Regionalization of the ganglion layer in the retina of the Magellanic Penguin (Spheniscus magellanicus)

SUBURO AM; HERRERO MV; SCOLARO A

WATERBIRDS (DE LEON SPRINGS, FLA.)

The Waterbird Society

Año: 1991 vol. 14 p. 17 - 24

1524-4695

The ganglion cell layer (GCL) of the retina of the Magellanic penguin (Spheniscus magellanicus) was studied with light microscopy. The analysis of cell size and cell density allowed the characterization of different GCL regions. An elongate central area without fovea and with maximum cell maximum densities of 7,800-12,000 cells/mm2 was found in the most dorsal portion of the ventral hemiretina. Higher cell densities were found in the remaining portions of the ventral hemiretina than in the dorsal hemiretina. Since the number and density of cells in the GCL are directly related to visual acuity, we conclude that the Magellanic penguin has less visual acuity than the pigeon and the domestic chicken. However, the non-uniform distribu- tion of the number and size classes of neurons reflects the presence of a topographical specialization of the retina that can be correlated with behavioral patterns of this species. Received 13 August 1990, accepted 22 January 1991.