Insect tissue is often difficult to prepare for electron microscopy because of the impenetrable barrier surrounding the body tissues. Drosophila salivary glands have been used for numerous studies because of the large size of the cells and their large polytene chromosomes. Early TEM studies of salivary glands used a protocol that took several days. We were able to achieve excellent preservation and good ultrastructure in Drosophila salivary glands and imaginal discs from Stage L3 larvae using microwave processing in a protocol requiring less than 2 hours.

We used a Pelco Laboratory microwave (model #3451) equipped with a Cold Spot, Steadytemp chiller/recirculator run at 15° C, and vacuum chamber (Ted Pella, Mountain Lakes, CA). The heads and attached salivary glands were removed from the animals and placed in PBS. The tissue was transferred to Pelco prep-eze specimen holders (#36157) for ease of handling. Our goal was to use the microwave effect, not the heating effect, to prepare the tissue.

Visuospatial processing is accomplished in distinct neuroanatomic pathways. One such pathway, known as the where pathway, involves a dorsal route through magnocellular thalamic cells to occipital and parietal cortices and conveys location and motion information. A second pathway, known as the what pathway, involves a ventral route through parvocellular thalamic cells to occipital and temporal cortices and conveys color and form information. The where pathway is thought to be responsible for processing spatial relationships while the what pathway is responsible for object identification. Children with early-treated congenital hypothyroidism (CH) who exhibit selective visuospatial deficits may provide a good model to study the differential development of these pathways. Because children with CH lacked thyroid hormone at a time when needed by developing brain regions such as the parietal cortex, these children may be affected to a greater degree on tasks tapping where but not what pathway processing. We tested this hypothesis via retrospective analysis of their performance on 6 spatial tasks. Compared were 49 adolescents with CH and 49 matched control participants. On the basis of confirmatory factor analysis, tasks were assigned to either where or what pathway groupings. A repeated measures ANOVA showed the CH group was impaired relative to a normal comparison group only on where pathway tasks. Regression analyses indicated that severity of early hypothyroidism was the strongest predictor of where pathway processing but had no effect on what pathway tasks. It is concluded that thyroid hormone is required during late gestation and early life for the normal development of the where aspects of visuospatial processing. (JINS, 2001, 7, 556–562.)

Several summers ago, while working at the Marine Biological Laboratory in Woods Hole, Massachusetts, George Augustine (Duke University) and I wished to look at the circulation in the giant synapse of the squid, Loligo pealei. At that time, Dr. Eugene Copeland suggested the use of India ink in order to see the circulatory system. The ink contains carbon particles that are visible under the EM. In addition, it is visible to the naked eye.