Expression of a keratin sulfate proteoglycan during development of the dorsal lateral geniculate nucleus in the ferret.

ABAKAN is a keratin sulfate proteoglycan that was identified in rat brain by monoclonal antibody TED15 (Geisert et al. [1992] Brain Res. 571:165-168). It blocks neuronal attachment and neurite outgrowth in culture, is associated with astrocytes, and marks the boundaries of areas in the developing rat brain (Geisert and Bidanset [1993] Dev. Brain Res., 75:163-173). In the present study TED15 was used to examine the distribution of ABAKAN during laminar development of the dorsal lateral geniculate nucleus in ferrets. This distribution was also compared with that of astrocytes as displayed with antibodies to GFAP. In the adult, TED15 and anti-glial fibrillary acidic protein (GFAP) labeling are similar. Both are fairly uniform in the nucleus although somewhat elevated near the optic tract and in the interlaminar zone between laminae A and A1. During development the pattern is quite different. At postnatal day 1 (P1), before lamination is evident, TED15 and anti-GFAP labeling are light in the nucleus. By P10, when laminae are emerging, both are elevated in the A-A1 interlaminar zone and in the C laminae. At P18, when laminae are distinct, TED15 labels the A-A1 interlaminar zone, and it marks the borders between the ON and OFF leaflets within A and A1 (Stryker and Zahs [1983] J. Neurosci. 3:1943-1951). In comparison, anti-GFAP marks the interlaminar zone but not the ON/OFF leaflets. By 6 weeks the nucleus resembles the adult nucleus. These results show that ABAKAN marks the boundaries of the major functional subdivisions of the lateral geniculate nucleus in the developing ferret and suggest that it plays a role in lamination.