DEVELOPMENT OF GLYCINERGIC CELLS AND PUNCTA IN NUCLEI OF THE SUPERIOROLIVARY COMPLEX OF THE POSTNATAL FERRET

The distribution of glycine-immunopositive cells and axonal endings wa s studied in the adult and early postnatal ferret superior olive. As i n other species, the most prominent glycine-immunopositive cell group in the adult ferret superior olive was the medial nucleus of the trape zoid body. Other darkly immunostained cells were present, although mor e scattered, in most periolivary regions, including the lateral and ve ntral trapezoid body nuclei. In the lateral superior olivary nuclei, g lycine-immunopositive cells were intermingled with immunonegative cell s. A comparable population of cells in the ipsilateral lateral superio r olivary nucleus was retrogradely labeled in cases with unilateral in jections of tritiated glycine in the inferior colliculus. Glycine-immu nopositive puncta were widely distributed in the neuropil in most peri olivary regions, including dense accumulations in the dorsomedial peri olivary region and ventral and lateral nuclei of the trapezoid body. I n the lateral and medial superior olivary nuclei, immunopositive punct a were distributed around the principal cells in characteristic periso matic halos. In postnatal ferrets, immunopositive cell bodies were fir st observed by postnatal day 7 and were distributed in regions compara ble to regions in the adult, with the exception that immunopositive ce lls in the lateral superior olivary nucleus did not appear until about postnatal day 28. There was diffuse staining in the neuropil in princ ipal and periolivary nuclei by postnatal day 7. During the third postn atal week, the immunostaining in the neuropil began to take on a more granular appearance and immunopositive puncta could be seen by postnat al day 35. In the lateral and medial superior olivary nuclei, the earl iest distribution of immunostaining in the neuropil was nonuniform, be ing greater in the high-frequency, medial, and ventral regions, respec tively. The density gradient in these areas was gradually eliminated o ver the next 2 postnatal weeks as immunostained processes and endings appeared over greater portions Of the nuclei. (C) 1995 Wiley-Liss, Inc .