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United States Department of Agriculture

Agricultural Research Service

Atlas on Ultrastructure of Infective Juveniles of the Soybean Cyst Nematode, Heterodera glycines

 

Chapter 8—Ultrastructure of Cuticular Exudates and Related Cuticular Changes in Juveniles of the Soybean Cyst Nematode, Heterodera glycines

Figure Captions

Figure 156. Longitudinal section of anterior region of infective Heterodera glycines J2 at 5 hours after inoculation, showing annulations of cuticle with flocculent intermediate zone (I) located between exocuticle (Ex) and endocuticle (En). Hemidesmosomes (hd) appear in pairs under each annulation. Ep, epicuticle; H, hypodermis; Sm, somatic muscles. Bar=0.5 µm.

 

Figure 157. Cuticle of amphidial cell region of parasitic J2 at 5 hours after inoculation, showing fibrils within J2 exocuticle (Ex) that appear similar in dimensions to striae of endocuticle (En). Hemidesmosomes (hd) appear uniformly stretched between endocuticle and somatic muscles (Sm). Ep, epicuticle; H, hypodermis; I, intermediate zone. Bar=0.5 µm.

 

Figure 158. Cuticle exudates and related secretory vesicles in hypodermis of J2 at 1 day after inoculation. At lip region of J2, stylet (St) is extended into initial syncytial cell located adjacent to metaxylem vessel. Hemidesmosomes (hd) are stretched within expanded hypodermis (H). RER, rough endoplasmic reticulum. Bar=1.0 µm.

 

Figure 159. Longitudinal section near stylet base, showing fibrillar exudations (fe) concentrated at annulations of cuticle. Electron-transparent secretory vesicles (SV) occur throughout cytoplasm of hypodermis. En, endocuticle; Ep, epicuticle; Ex, exocuticle; SA, secretion accumulation zone; Sm, somatic musculature. Bar=1.0 µm.

 

Figure 160. Third-stage specimen showing fibrillar exudations (fe) along annules of cuticle. En, endocuticle; H, hypodermis; I, intermediate zone; N, nucleus; NP, nerve process. Bar=1.0 µm.

 

Figure 161. Transverse section of J2 at 2 days after inoculation, showing hypodermal (H) cord region with nucleus surrounded by Golgi apparatus (GA) and secretory vesicles (SV). Vesicles occur near apical membrane of hypodermis where their contents may transfer to secretion accumulation zone (SA) lying between plasmalemma and base of endocuticle (En). Fibrillar exudates (fe) accumulate on surface of epicuticle (Ep). Ex, exocuticle; N, nucleus; Pm, protractor muscles; St, stylet. Bar=1.0 µm.

 

Figure 162. Longitudinal section of J2 at 2 days after inoculation, showing fibrillar exudates (fe) on cuticle surface near stylet region. Section through hypodermal cord shows elongated nucleus (N) and extensive accumulation of secretory vesicles (SV) adjacent to apical membrane (M) of hypodermis (H). En, endocuticle; Ep, epicuticle; Ex, exocuticle; GA, Golgi apparatus; I, intermediate zone; Nu, nucleolus; SA, secretion accumulation zone. Bar=1.0 µm.

 

Figure 163. Enlargement from fig. 162 showing fibrillar exudate continuity with portions of cuticle. Bar=0.5 µm.

 

Figure 164. Exudates on cuticle of parasitic J2 at 3 days after inoculation. Cross section immediately posteriad from cephalic region shows fibrillar exudates (fe) on cuticle surface. CF, cephalic framework; En, endocuticle; Ep, epicuticle; Ex, exocuticle; H, hypodermis; St, stylet. Bar=1.0 µm.

 

Figure 165. Longitudinal section near cephalic region of J2 at 3 days after inoculation, showing dense accumulations of fibrillar exudates (fe) on cuticle surface. En, endocuticle; Ep, epicuticle; Ex, exocuticle; H, hypodermis; I, intermediate zone; Sm, somatic musculature; SV, secretory vesicles. Bar=1.0 µm.

 

Figure 166. Cuticle separation and early stages of second molt of Heterodera glycines at 4 days after inoculation. Longitudinal section shows electron-opaque deposits (EOD) between J2 endocuticle and developing outer boundaries of J3. Stylet (St) is retained within stomatal wall (SW) and cephalic framework (CF). Residual fibrillar exudates (fe) are present on second-stage cuticle. En, endocuticle; Ep, epicuticle; Ex, exocuticle. Bar=1.0 µm.

 

Figure 167. Cuticle separation and early stages of second molt of Heterodera glycines at 4 days after inoculation. Tangential section below that of fig. 166 shows outlines of transparent (SVt) and electron-opaque (SVo) secretory vesicles near apical membrane of hypodermis. Residual fibrillar exudate (fe) adheres to J2 cuticle. CJ2, cuticle of J2; CJ3P, cuticle of CJ3 primordium; EOD, electron-opaque deposits; En, endocuticle; Ep, epicuticle; Ex, exocuticle. Bar=1.0 µm.

 

Figure 168. Ecdysis of parasitic Heterodera glycines J2 at 6 days after inoculation. Entire anterior midcentral portion of J2 has deteriorated. Stylet ( St) and stomatal wall (SW) are retained in contact with J2 cuticle. Tissues at base of invaginated anterior are close to site of J3 stylet initials. Bar=1.0 µm.

 

Figure 169. Longitudinal section through secretory-excretory gland of parasitic Heterodera glycines J2 at 6 days after inoculation. Fine reticulate material (FRM) is concentrated near secretory-excretory pore. Remnants of fibrillar to amorphous exudates (AE) adhere to J2 cuticle. Outer boundary of J3 consists of trilaminar membrane from which short fibrillar projections appear to form on a primordial J3 cuticle ( CPJ3). CJ2, cuticle of J2; S–EC, secretory-excretory canal. Bar=1.0 µm.

 

Figure 170. Longitudinal section of parasitic J2 at 6 days after inoculation, showing cuticle of J2 (CJ2) separated from J3. Modification of apical membrane of J3 hypodermis toward cuticle differentiation is minimal. Space between J2 cuticle and J3 body is filled with reticulate material but lacks appearance of fine reticulate accumulations observed near secretory-excretory canal pore. CPJ3, cuticle primordium of J3; En, endocuticle; Ep, epicuticle; Ex, exocuticle; H, hypodermis; I, intermediate zone. Bar=1.0 µm.

 

Figure 171. Inset showing cuticle primordium of J3. M, hypodermal membrane. Bar=0.1 µm.

 

Figure 172. Longitudinal sections of Heterodera glycines J3 at 6 days after inoculation, showing newly formed stylet. In contrast to earlier stages of J3 (see figs. 168–170), stylet (St) formation is well advanced and stylet is surrounded by thick stomatal wall (SW). J3 cuticle (CJ3) is multizoned. CJ2, cuticle of J2; FRM, fine reticulate material. Bar=1.0 µm.

 

Figure 173. Longitudinal sections of J3 at 6 days after inoculation, showing secretory-excretory pore site. Section through secretory-excretory pore (S–EP) and gland (S–EG) shows segments of J2 secretory-excretory gland duct walls (S–EDWJ2) within newly formed J3 duct wall (S–EDWJ3) or remnants of J2 duct wall accumulated between J2 (CJ2) and J3 cuticles (CJ3). FRM, fine reticulate material. Bar=1.0 µm.

 

Figure 174. Longitudinal sections of J3 showing secretory-excretory pore site at 6 days after inoculation. Section of specimen in fig. 173 at higher magnification shows a part of secretory-excretory canal within invaginated J3 cuticle that forms secretory-excretory pore (S–EP). CJ2, cuticle; FRM, fine reticulate material; S–EDWJ2, secretory-excretory gland duct wall of J2; S–EG, secretory-excretory gland. Bar=1.0 µm.

 

Figure 175. Longitudinal sections of J3 showing deteriorated J2 cuticle at 6 days after inoculation. Sector of J3 shows well-developed cuticle (CJ3) and detached convoluted J2 cuticle (CJ2). DG, dorsal gland; EL, esophageal lumen; GA, Golgi. Bar=1.0 µm.

 

Figure 176. Longitudinal section of Heterodera glycines J3 at 7 days after inoculation, showing the developing anterior region of J3 with stylet (St) supported by stomatal wall (SW). Thick cuticle of J3 (CJ3) contrasts with deteriorated J2 cuticle (CJ2), consisting mainly of epicuticle (EpJ2). EpJ3, epicuticle of J3; Pm, protractor muscles; Sm, somatic muscles. Bar=1.0 µm.

 

Figure 177. Transverse sections of J3 at 7 days after inoculation, showing stylet cone (St) residue at extreme anterior of J3 in fig. 176. Bar=1.0 µm.

 

Figure 178. Transverse section of J3 at 7 days after inoculation, showing third-stage juvenile cuticle (CJ3) with interrupted bands of narrow striated endocuticle (En) and thick basal layer (BL). Remaining J2 epicuticle (EpJ2) lies adjacent to J3 cuticle (EpJ3). Dg, dorsal gland; H, hypodermis. Bar=1.0 µm.


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Last Modified: 2/6/2002
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