Date of Award

1-1-1981

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Anatomy and Cell Biology

Abstract

Rat pups suckled to severely zinc deficient mothers from birth were killed at 21 days of age. The cerebella were then examined by light and electron microscopy. Dendritic development was analyzed on Golgi-stained sections both qualitatively and quantitatively. Impaired pup growth, alopecia, hunched back posture and decreased femur zinc were seen in zinc deficient pups. Zinc deficiency impaired cerebellar development. The cerebellum was smaller and had fewer granule cells. The molecular layer was thinner and there was a persistence of the external granule cell layer. The normal cytoarchitecture of the cerebellar cortex was maintained in zinc deficient pups; however, basket, stellate and Purkinje cell dendritic development was impaired. Purkinje cells exhibited decreased dendritic branching and smaller dendritic fields. In addition, they had multiple primary dendrites and extrasomatic processes. Ultrastructurally the Purkinje cell somas were less mature. In response to the altered cerebellar growth, climbing fiber and basket fiber maturation was impaired. Purkinje cells still showed somatic spine-climbing fiber synapse, and the frequency of basket fiber synapses on the soma and around the pinceau was decreased. In addition, some parallel fiber varicosities were found to synapse with three to five Purkinje cell branchlet spines. Basket and stellate cells showed a decrease in the number of dendritic segments, total dendritic length and dendritic field area. The area of the soma was unaffected. The decreased number of granule cells indicated that zinc deficiency retarded the production of granule cells. The decreased granule cell to Purkinje cell ratio suggested that the impaired dendritic development in zinc deficient pups was in part due to a failure of the growing dendrites to interact with an appropriate number of parallel fibers. However, changes in the metabolism of the cells may have contributed to the impaired dendritic development.Pair-fed pups were used as controls for the anorexia associated with zinc deficiency. The effects of undernutrition on cerebellar and dendritic growth were mild. Pair-fed pups displayed less severe reductions in body weight, cerebellar growth and dendritic branching. These observations indicated that anorexia experienced by the mother was only a partial contributor to the findings in zinc deficient pups.

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