The Structure and Development of the Dorsal Bristle Complex of Oxytricha fallax and Stylonychia pustulata*
This investigation was supported at Indiana University by Research Grant GM15410, from the National Institute of General Medical Sciences (to T. M. Sonneborn), and Genetics Training Grant GM 82, from the National Institute of General Medical Sciences, U. S. Public Health Service, and in Hofstra University by Institutional Grant GU-3556, from the National Science Foundation. The technical asssistance of Mr. Michael Johnell is acknowledged with thanks.
Abstract
SYNOPSIS. Oxytricha fallax and Stylonychia pustulata possess 6 rows of dorsal bristle units. Each dorsal bristle unit consists of a pair of kinetosomes; the anterior kinetosome has a cilium and the posterior kinetosome a ciliary stub. The kinetosome pair, located at the bottom of a cortical pit surrounding the cilium and ciliary stub, is surrounded by an asymmetrical fibrillar mass. Future rows 1-4 are formed from 2 sets of primordia originating within mature dorsal rows 1-3. Rows 5 and 6 originate from the anterior regions of both right marginal cirral primordia. Old dorsal bristle units utilized in formation of primordia are presumably maintained in the new rows of the proter and opisthe; those outside the primordia are resorbed. The morphogenetic pattern of the Oxytrichidae is similar to those of the Urostylidae and Holostichidae, but quite different from that of the Euplotidae.
