Ontogenetic Development of the Subcommissural Organ with Reference to the Flexural Organ

The ontogeny of the chick and rat subcommisural organ (SCQ) has been the subject of several reports. Some of these studies were performed on the rat SCO (Kohl and Linderer 1973; Marcinkiewicz and Bouchaud 1983, 1986; Rakic and Sidman 1968; Naumann et al. 1987; Castaneyra-Perdomo et al. 1983). The SCO of chicken embryos represents the nonmammalian organ model whose ontogenetic development has been most thoroughly investigated (Wingstrand 1953; Ziegels 1977; Schoebitz et al. 1986; Bruel et al. 1987; Naumann et al. 1987; Karoumi et al. 1990). Using classical stains for neurosecretion, Wingstrand (1953) and Ziegels (1977) have reported that the secretory material of the SCO first appears in 7-day-old chick embryos.