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Chapter 6—Ultrastructure of Subventral Gland Secretory Granules in Parasitic Juveniles of the Soybean Cyst Nematode, Heterodera glycines

Figure Captions

Figure 126. Lateral submedial longitudinal section of Heterodera glycines J2 near a feeding site at 5 hours after inoculation. Stylet is retracted. Pm, protractor muscle; Sm, somatic muscle. Bar=1.

Figure 127. Longitudinal section of Heterodera glycines J2 at 1 hour after inoculation. Section through metacorpus valve (mv) region shows accumulations of small electron-opaque secretory granules (SG) in dorsal gland extension (Dx) and larger, sometimes electron-opaque granules in subventral gland ampulla (SvA). mm, metacorpus muscle. Bar=1.0 µm.


Figure 128. Longitudinal section of J2 at 1 hour after inoculation, showing segment of gland extensions that typify secretory granule morphology throughout subventral gland cell and extension (Svx). Adjacent to subventral gland extension, enlarged lumen of esophago-intestinal valve (Eiv) indicates that nematode is in feeding mode. Bar=1.0 µm.


Figure 129. Longitudinal section through subventral gland cell extension of parasitic J2 at 3 hours after inoculation on susceptible soybean cultivar 'Lee'. Gland cell extensions near lateroventral commissure of nerve ring show secretory granules (SG) of very low electron density, some of which have small electron-opaque matrices (arrows). Bar=1.0 µm.


Figure 130. Nucleus (N) in subventral gland cell, surrounded by Golgi (GA) and numerous secretory granules (SG) with various levels of electron density. Bar=1.0 µm.


Figure 131. Section through subventral gland, showing Golgi with cisternae stacks (arrows) facing each other. Condensing vesicles (cV) merge to form secretory granules (SG). Bar=1.0 µm.


Figure 132. Transverse section of subventral gland of J2 at 5 hours after inoculation of a resistant soybean cultivar, 'Pickett 71'. Section through central region of gland shows enlarged nucleus (N) surrounded by Golgi (GA), secretory granules (SG), mitochondria (Mc), and dense matrix of rough endoplasmic reticulum (RER). Arrows, electron-opaque region; Nu, nucleolus. Bar=1.0 µm.


Figure 133. Secretory granules within ampulla are electron-translucent except for small residues of electron-opaque material (Sgr). Svv, subventral gland valve. Bar=1.0 µm.


Figure 134. Electron-opaque secretory granules (SG) accumulated at anterior of gland body. Some granules contain electron-opaque regions (arrows) within their granule matrices. Bar=1.0 µm.


Figure 135. Longitudinal section of J2 at feeding site in resistant cultivar 'Bedford' at 18 hours after inoculation. The moderately dense cytoplasm in an initial syncytial cell (ISC) indicates host response to infection. Stylet lumen is obscured by electron-opaque deposits and has a ventrally located aperture for food uptake. St, stylet. Bar=1.0 µm.


Figure 136. Electron-opaque secretory granules (SG) within subventral gland ampulla (SvA), before transfer of contents into esophageal lumen via subventral gland valve (Svv). Bar=1.0 µm.


Figure 137. Transverse section through subventral gland cell of Heterodera glycines at 2 days after inoculation, showing Golgi (GA) associated with secretory granules (SG) and flocculent secretory bodies (FSB) that occupy large regions of subventral gland. Mc, mitochondria. Bar=1.0 µm.


Figure 138. Transverse section through gland extensions anteriad from nerve ring, showing secretory granules (SG) of subventral gland extensions (Svx) with small dense cores. In contrast, secretory granules of dorsal gland extension (Dx) are larger and moderately electron opaque. Bar=1.0 µm.

Figure 139. Transverse section of J2 at 3 days after inoculation, showing closed subventral gland valves (Svv) and accumulations of secretory granules (SG) within the ampullae and near the valves. Larger secretory granules occur in dorsal gland extension (Dx). Mt, microtubules. Bar=1.0 µm.

Figure 140. Transverse section through Heterodera glycines J2 at 4 days after inoculation, showing subventral gland valves (Svv) in open position. Valves and secretory granules (SG) have contents with similar and varied levels of electron density. SvA, subventral gland ampulla. Bar=1.0 µm.


Figure 141.Transverse section through a subventral gland at 4 days after inoculation, showing electron-translucent flocculent secretory bodies (FSB) within dense matrix of cytoplasm. Mc, mitochondria. Bar=1.0 µm.


Figure 142. Transverse section through esophageal gland extensions in nerve ring region of a Heterodera glycines third-stage juvenile, J3, at 5 days after inoculation, showing contrast in secretory granule morphology of dorsal (Dx) and subventral gland extensions (Svx). Secretory granules (SG) of subventral glands are considerably smaller than those of dorsal gland and vary widely in electron density. Bar=1.0 µm.


Figure 143. Longitudinal section through portions of dorsal and subventral glands of Heterodera glycines J3 at 6 days after inoculation. Nuclei of dorsal gland (DN) and of one subventral gland (SvN) are seen. Moderate-sized flocculent secretory bodies (FSB) with various levels of electron density are distributed throughout subventral gland. Bar=1.0 µm.


Figure 144. Subventral gland valve of Heterodera glycines J2 during root penetration at 5 hours after inoculation, showing secretory granule (SGd) with partially depleted contents adjacent to valve membrane. Electron-opaque secretory granules (SG) in ampullae are similar in electron density to numerous granules in gland extension. Svv, subventral gland valve. Bar=1.0 µm.


Figure 145. Open subventral gland valves (Svv) of Heterodera glycines J3 at 8 days after inoculation, filled with electron-opaque material similar to contents of adjacent secretory granules (SG) in ampullae. Small, relatively electron-opaque secretory granules show a sharp contrast to secretory granules in subventral glands of H. glycines J2 during shorter infection periods, as described in fig. 144. Bar=1.0 µm.

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Last Modified: 8/12/2016
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