Comparative ultrastructural observations of the Egyptian schistosomes: Schistosoma mansoni and Schistosoma haematobium

Abstract

An ultrastructural topography has been made to the tegumental architectures of two Egyptian schistosomes namely S. mansoni and S. haematobium hosted in a model animal namely Cricentus auratus. The distribution of sensory papillae on the oral sucker were arranged in one circle around the rim in addition to some papillae in upper part of inner zone in male, female S. mansoni and in male S. haematobium. The differences in the types of papillae, their distribution and shape of ridges on various parts of the body surface which are quite specific for each species was studied. Also, the ventral tegument of female's displays larger and more numerous sensory papillae. Both ciliated and non-ciliated papillae were observed in this work which makes a link with another species of schistosome S. japonicum. Another characteristic feature in this study is unique of male of S. haematobium, the extensive formation of ridges and transformation to microvilli in the posterior region in males. These finding may provoke further study of schistosomes hosted in animal model for more detailed investigation at the molecular level.

Keywords: Animal model; SEM; Schistosomes; Tegument.

Figs. 1–8

Scanning electron micrographs of adult male Schistosoma mansoni. 1 Paired male (M) and female (F) showing the anterior and posterior ends of female emerge from the gynaecophoral canal (GC). 2 Whole mount of the male showing the gynaecophoral canal (GC). 3 Top view of oral sucker (OS) showing hemispherical papillae (HP), inner zone of oral sucker (IZ), mouth (Mo) and rim of oral sucker (Rm). 4a Rim of the oral sucker showing sharp spines (S). b Inner zone (IZ) of oral sucker showing hemispherical papillae (HP) and spines (S). 5 Ventral sucker (VS) showing rim (Rm), inner zone (IZ) and central zone (CZ). 6 Edge of the ventral sucker with hemispherical papillae (HP) and spines. 7 Magnification of the ventral sucker surface with spines. 8a Dorsal surface of area between two suckers. b Magnification of anterior dorsal area between the two suckers showing different sizes of hemispherical papillae

Figs. 9–18

Scanning electron micrographs of adult male S. mansoni.9 Magnification of the posterior dorsal surface of area between two suckers showing rows of low wavy ridges with hemispherical papillae (HP) and digtal form papillae (DiP). 10 Last portion of the body showing tubercles (T), dome papillae (DP), hemispherical papillae (HP) and macule papillae (MaP). 11 Inner surface of left edge of the canal with minute spines and hemispherical papillae (HP). 12 Inner surface of the canal; well-developed folds. 13 Magnification of anterior inner surface of the canal; hemispherical papillae (HP) and little number of minute spines. Note many clefts. 14 Middle inner surface of the canal with hemispherical papillae (HP) and moderate number of spines. 15 Posterior inner surface of the canal; hemispherical papillae (HP) and numerous spines. 16a Dorsal view of posterior region of the male. Note few numbers of tubercles, spines between tuberclesand the excretory pore (EP). b Ventral view of posterior region of the male showing hemispherical papillae (HP). 17 The most extremely posterior region of the male showing macule papillae (MaP) and cratered papillae (CrP). 18 The most extremely posterior region of the male. Note the presence of digital-form papillae (DiP) and macule papillae (MaP)

Figs. 19–29

Scanning electron micrographs of adult female S. mansoni. 19 Whole mount of female showing anterior part (An), middle proximal (MP) region, middle distal (MD) region and posterior part (Po). 20 Anterior region of female showing the oral sucker (OS) and ventral sucker (VS). 21 Magnification of the oral sucker. Note the hemisphericalpapillae (HP) and spines. 22 The surface between the suckers. Note the hemispherical papillae (HP). 23 Magnification of the ventral sucker. Note spines and hemispherical papillae (HP). 24 Magnification of dorsal surface; hemispherical papillae (HP) and some pores. 25 The lateral surface of middle proximal region. Note pitted tegument. 26 The dorsal surface of middle proximal region showing hemispherical papillae (HP). 27 The dorsal surface of middle distal region. Note presence of few spines (S). 28 Magnification of dorsolateral surface. Note presence of spines (S), spikes (Sp) and dome-shape papillae (DP). 29 Posterior extremely showing hemispherical papillae (HP), excretory pore (EP) and profusely spines (S). Note spines directed anteriorly

Figs. 30–39

Scanning electron micrographs of adult male S. haematobium. 30. Ventral and dorsal view of conjugating male (M) and female (F) S. haematobium showing complete closed gynaecophoral canal (GC). 31 Ventral view of whole mount of male showing closed gynaecophoral canal. 32 Ventral view of anterior region showing oral (OS) and ventral (VS) suckers. Note two rows of fungiform papillae (FP). 33 Ventral view of oral sucker (OS) showing some thin rim (Rm), large inner zone (IZ) and oral cavity (OC). Note numerous hemispherical papillae (HP) outside the inner zone. 34 Rim of the oral sucker showing corrugated tegument, small cratered papillae (CrP) with radiating ridges, some pores (Po), few number of hemispherical papillae (HP). Note sharp and sparse spines (S). 35 Magnification of rim showing rough, long and sharp spines (S) and hemispherical papillae (HP). 36 High magnification of Fig. 32. Note rough, sharp and fungi form spines (S), corrugated tegument with many pores (Po). 37 Ventral sucker showing four zones; rim (Rm), narrow zone (NZ), large inner zone (IZ) and central zone (CZ). 38 Rim of ventral sucker showing highly folded tegument, few hemispherical papillae (HP), pores (Po) and short and sparse spines (S). 39 Sector of ventral sucker showing narrow zone (NZ) with pitted sheet tegument and hemispherical papillae (HP) only between two spinous zones

Figs. 40–47

Scanning electron micrographs of adult male S. haematobium. 40 Magnification of inner zone of ventral sucker. Note some hemispherical papillae (HP) and sharp spines (S). 41 Central zone of ventral sucker; a more extensive development branching ridges, (Ri), digital papillae (DiP), hemispherical papillae (HP) and non-ciliated cratered papillae (CrP). Note pitted rim and ridges radiate from CrP. 42 Ventral surface of anterior region showing a row of fungi form papillae (FP) and lateral spikes (Sp). Note transverse wavy ridges. 43 Magnification of Fig. 42. Note wavy ridges (Ri), fungi form papillae (FP), hemispherical papillae (HP) and squarish papillae (SP). 44 Dorsal surface of anterior region. 45 Magnification of Fig. 44. Note numerous digital papillae (DiP), pores (Po) and hemispherical papillae (HP). Note well development branching ridges (Ri). 46 Anterior part of dorsal surface showing numerous cratered papillae (CrP), digital papillae (DiP), hemispherical papillae (HP) and squarish papillae (SP). 47 Tegument of dorsal surface showing distribution of tubercles (T); anterior part (a) with few number of tubercles, middle part (b) with moderate number and posterior part (c) with numerous tubercles (T)

Figs. 48–52

Scanning electron micrographs of adult male S. haematobium. 48 Right edge of gynaecophoral canal (GC) provided by non-ciliated and ciliated cratered papillae. Note cilia (Ci). 49 Right edge of gynaecophoral canal showing highly pitted tegument with ciliated cratered papillae that seemed to be secretory, macules (MaP) and hemispherical (HP) papillae. Cilia (Ci) and secretion (Se). 50 View of middle third of the body showing numerous and small fungi form papillae (FP) interspersed among the dorsal tubercles, ciliated dome papillae (DP2), dome papillae (DP3) and dome papillae with knob (DP1). 51a Inner surface of anterior and middle part of gynaecophoral canal showing long and sharp spines. b Inner surface of posterior part of gynaecophoral canal showing slightly pitted tegument seemed to be disrupted by short and stubby spines. 52 Magnification of Posterior extremely end showing ridges (Ri) transform to leaf-like and microvilli (MV) like projections. Note accumulation of very numerous fungi form papillae (FP)

Figs. 53–55

Scanning electron micrographs of adult female S. haematobium.53a Ventral surface of anterior region showing oral sucker with mouth opening (MO). Note two circles of hemispherical papillae (HP) and spikes (Sp). b Magnification of the oral sucker showing spongy appearance tegument, mouth opening (MO), hemispherical papillae (HP) and spikes (Sp). Note spines directed inward. 54 Tegument of flat sheet ventral surface. Note invagination by numerous minute pores. Note numerous small hemispherical papillae (HP). 55 Magnification of lateroventral aspect of anterior region showing digital papillae (DiP), hemispherical papillae (HP) and spines (S). Note wavy branching ridges

Figs. 56–61

Scanning electron micrographs of adult female S. haematobium.56 Ventral sucker showing pitted tegument with short and stubby spines and some hemispherical papillae (HP). 57 Tegument of the ventral surface showing folds, digital papillae (DiP), hemispherical papillae (HP) and spines (S). 58 Magnification of the lateral region showing folds and hemisphericalpapillae (HP). Note corrugated folds tegument. 59 Magnification of the lateral region showing folds. Note corrugated folds tegument. 60 Dorsal surface showing tegument with corrugated pierced folds. 61 Posterior extremely showing excretory pore (EP), corrugated pierced tegument with sharp spines (S) and hemispherical papillae (HP)