The musculature and associated innervation of adult and intramolluscan stages of Echinostoma caproni (Trematoda) visualised by confocal microscopy

Gross anatomy of muscle and sensory/motor innervation of adult and intramolluscan developmental stages of Echinostoma caproni have been investigated to ascertain the organisation and the functional correlates of any stage-specific patterns of staining. Using indirect immunocytochemistry to demonstrate neuroactive substances and the phalloidin-fluorescence technique for staining myofibril F-actin, the muscle systems and aminergic and peptidergic innervation of daughter rediae, cercariae, metacercariae, and pre- and post-ovigerous adults were examined and compared using confocal scanning laser microscopy. A complex arrangement of specific muscle fibre systems occurs within the body wall (composed of circular, longitudinal and diagonal fibres), suckers (radial, equatorial, meridional), pharynx (radial, circular), gut caeca (mainly circular), cercarial tail (circular, pseudo-striated longitudinal), and ducts of the reproductive system (circular, longitudinal), presumed to serve locomotor, adhesive, alimentary and reproductive functions. Immunostaining for serotonin (5-HT) and FMRFamide-related peptides (FaRPs) was evident throughout the central (CNS) and peripheral (PNS) nervous systems of all stages, and use of dual-labelling techniques demonstrated separate neuronal pathways for 5-HT and FaRP in both CNS and PNS. FaRP expression in the innervation of the ootype wall was demonstrated only in post-ovigerous worms and not in pre-ovigerous worms, suggesting an involvement of FaRP neuropeptides in the process of egg assembly. Comparison of the present findings with those recorded for other digeneans suggests that muscle organisation and innervation patterns in trematodes are highly conserved.

Leisure goods, education attainment and fertility choice

This paper proposes a novel mechanism for the fertility decline that occurred across the world since the late nineteenth century. It suggests that the rise in the cost of children relative to leisure goods in the process of development contributed to the decline in fertility. The paper develops a unified growth model in which children are substitutes for leisure goods in the parental utility function. The theory suggests that the rise in income, the decline in the relative price of leisure goods and the increase in educational attainment in the process of development speed up the demographic transition from high to low fertility and contributed to the transition from stagnation to growth.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF A SALMFAMIDE-LIKE NEUROPEPTIDE IN THE NERVOUS-SYSTEM OF ADULT AND LARVAL STAGES OF THE HUMAN BLOOD FLUKE, SCHISTOSOMA-MANSONI

The localization and distribution of SALMFamide immunoreactivity (IR), SI(GFNSALMFamide), in the nervous system of both the adult and larval stages of the trematode Schistosoma mansoni has been determined by an indirect immunofluorescent technique in conjunction with confocal scanning laser microscopy (CSLM). Immunostaining was widespread in the nervous system of adult male and female S. mansoni. In the central nervous system (CNS), IR was evident in nerve cells and fibres in the anterior ganglia, cerebral commissure and dorsal and ventral nerve cords. In the peripheral nervous system (PNS), IR was apparent in nerve plexuses associated with the subtegmental musculature, oral and ventral suckers, the lining of the gynaecophoric canal, and in fine nerve fibres innervating the dorsal tubercles of the male worm. In the reproductive system of male and female worms, S1-IR was only observed around the ootype/Mehlis' gland complex in the female. Immunostaining was also evident in the nervous system of both miracidium and cercarial larval stages. A post-embedding, IgG-conjugated colloidal gold immunostaining technique was employed to examine the subcellular distribution of SALMFamide-IR in the CNS of S. mansoni. Gold labelling of peptide was localized over dense-cored vesicles within nerve cell bodies and fibres constituting the neuropile of the anterior ganglia, cerebral commissure and nerve cords of the CNS. Antigen pre-absorption studies indicated that the results obtained do suggest S1-like immunostaining and not cross-reactivity with other peptides, in particular FMRFamide.

FASCIOLA-HEPATICA - TEGUMENTAL SURFACE CHANGES IN ADULT AND JUVENILE FLUKES FOLLOWING TREATMENT IN-VITRO WITH THE SULFOXIDE METABOLITE OF TRICLABENDAZOLE (FASINEX)

The effects of the novel benzimidazole, triclabendazole (Fasinex, Ciba-Geigy), in its active sulphoxide metabolite form (TCBZ-SX), on the tegumental surface of Fasciola hepatica has been examined in vitro. The tegument of adult flukes incubated in TCBZ-SX (50 mug/ml) appeared swollen and blebbed after only 6 h. In addition, progressive spine loss at the oral cone was evident following 12 h treatment. After 24 h, the tegumental syncytium and spines had completely sloughed away, leaving an exposed basal lamina and empty spine sockets. Juvenile flukes (3 weeks old) also demonstrated tegumental alterations after treatment with TCBZ-SX (20 mug/ml). The syncytium became extremely roughened and corrugated on both dorsal and ventral surfaces after only 3 h. Following 6- and 9-h incubations, there were many deep furrows, which were especially pronounced on the ventral surface, and by 18 h, the juvenile tegument was severely disrupted, especially on the ventral surface. In all cases, the effects were more marked than in the previous incubation periods. The results confirm the potent activity of triclabendazole against F. hepatica and suggest that the tegument of adult and juvenile flukes may be a target organ for this important fasciolicide.