Margaret Hollyday
Professor and Chairman
I am a developmental biologist with particular interests in the development of the vertebrate nervous system. My research focuses on development of the vertebrate nervous system using the chick embryo as a model system. My broad intellectual objectives are to understand how different regions of the nervous system become different one from the other and how these differences manifest themselves by differential regulation of neuronal proliferation, migration and synapse formation between specific classes of neurons. In the laboratory, we are currently studying the proliferation kinetics of neuronal precursors in the chick embyro neural tube. We use bromodeoxyuridine (BrdU) immunohistochemistry to label cells synthesizing DNA. By varying the time available for BrdU incorporation and determining the proportion of labeled and unlabeled cells in tissue sections at these varying times, we can estimate the duration of various phases of the proliferative cell cycle. We have observed regional differences in labeling indices, and are in the process of relating those differences to morphological subdivisions of the embryonic neural tube known as neuromeres. The long range goal of this project is to use these methods in combination with genomic markers for neural tube regionalization to study the relationship between cell proliferation kinetics and regional specification, and to address questions about the regulation of those processes during development. Other interests include axon guidance, neuronal cell death and regulation of gene expression.
Hollyday, M. and M. Morgan-Carr (1995) Chick Wing Innervation: II. Morphology of motor and sensory axons and their growth cones during early development. J. Comp. Neurol. 357:254-271.
Ferns, M.J. and M. Hollyday (1995) Chick Wing Innervation: III. Collateral branching during development of limb innervation in the chick. J. Comp. Neurol. 357:272-280.
Gutman, C., M. K. Ajmera and M. Hollyday (1993) Organization of motor pools supplying axial muscles in the chicken. Brain Res. 609:129-136.
Phelan, K. A. and M. Hollyday (1990) Axon guidance in chick wings: the role of muscle cells in motoneuronal pathway selection and muscle nerve formation. J. Neuroscience. 10:2699-2716.
Whitelaw, V. and M. Hollyday (1983) Thigh and calf discrimination in the motor innervation of the chick hindlimb following deletions of limb segments. J. Neuroscience. 3: 1199-1215.
Hollyday, M. and V. Hamburger (1977) An autoradiographic study of the formation of the lateral motor column in the chick embryo. Brain Res. 321: 197-208.
Hollyday, M. and V. Hamburger (1976) Reduction of normally occurring motor neuron depletion following supernumerary limb transplantation in chick embryo. J. comp. Neurol. 170: 321-320.