Changes Associated with Parasitism in Nematodes. II. Histochemical and Microspectrophotometric Analyses of Preparasitic and Parasitic Larvae of Meloidogyne javanica

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Abstract
The esophageal regions of second-stage larvae of M. javanica were examined with a UV [ultraviolet] microspectrograph. Both preparasitic and parasitic larvae contained large numbers of nuclei anterior and posterior to the nerve ring so that the outline of this structure was seen in contrast to a background of UV absorbing material. Examination of absorption curves at a wavelength of 260 m/[mu]. through the ducts of the subventral esophageal glands together with spectral analyses of points on these curves, with and without treatment with ribonuclease and deoxyribonuclease, showed that in both preparasitic and parasitic larvae these structures did not contain nucleic acids but contained substances which gave a typical protein absorption curve under UV. This curve was more pronounced in the ducts of the preparasitic larvae than in those of the parasitic larvae. Histochemical tests on both these types of larvae supported the results obtained with the microspectrograph and showed that the contents of the ducts of the subventral esophageal glands change their chemical composition within 2 to 3 days of entering the host plant and become strongly periodic acid-Schiff positive. The hypothesis that the subventral esophageal glands of nematodes have more than one function is discussed in the light of these experiments.