الفهرس 
Environmentally induced arrestOnly 14 pages are availabe for public view
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Abstract
Developmental a r r e s t by immature nematodes in t h e i r normal d e f i n i t i v e hosts is being increasingly recognized as a common a l t e r n a t i v e t o uninterrupted development and maturation. Arrested larvae a r e now known t o occur in more than 35 species of p a r a s i t i c nematodes of diverse taxonomic a f f i n i t y (Michel 1974). The p o t e n t i a l f o r including r e s t i n g stages is inherent in the basic p a t t e r n of nematode development, a s the lethargus accompanying each moult represents an opportunity f o r the i n t e r p o l a t i o n of an obligatory or f a c u l t a t i v e hypobiotic stage (Schad 1977) . Among nematodes, under c e r t a i n conditions larvae of many strongylid nematodes become dormant during the histot r o p i c phase of t h e i r development and t h e i r maturation is delayed. This phenomenon, often r e f e r r e d a s a r r e s t e d l a r v a l development, l a r v a l i n h i b i t i o n or l a r v a l hypobiosis, occurs during i n f e c t i o n s of t r i c h o s t r o n g y l i d nematodes in the stomach of herbivorous hosts, The stage a t which development is i n h i b i t e d has been found t o be d i f f e r e n t in d i f f e r e n t species, and the mechanisms involved appear t o be complex, According t o generally accepted opinions, i n h i b i t e d development of nematodes depends on external environmental f a c t o r s , host f a c t o r s and p a r a s i t e - r e l a t e d f a c t o r s , Each of these f a c t o r s , e i t h e r alone or together with the other two, induces a r r e s t , The aim of the present work was t o find out, under laboratory conditions and in the laboratory model system (Obeliscoides c u n i c u l i - r a b b i t ) , the mechanisms of the i n h i b i t i o n phenomenon, whether phenological or/and immunol o g i c a l . For such purpose f i v e experiments were c a r r i e d out , t o i n v e s t i g a t e : ( 1 ) the e f f e c t of dose of i n f e c t i v e larvae on the degree of i n h i b i t i o n and e f f e c t i v e n e s s of i n f e c t i o n ; (2) the seasonal nature of a r r e s t e d development; (3) the e f f e c t of storage a t 4OC on the degree of l a r v a l i n h i b i t i o n ; ( 4 ) the evaluation of the l o c a l secretory and systemic a n t i - body response during s i n g l e and challenge i n f e c t i o n s ; (5) the influence of immunosuppressive and immunostimulative agents on the l o c a l and systemic immunity. The s e r i e s of experiments were c a r r i e d out using a d u l t outbred Polish race r a b b i t s of both sexes infected with a a equa t e dose of L 3 -0. c u n i c u l i . Dynamics of egg p e r gram production, e f f e c t i v e n e s s of i n f e c t i o n and percent of l a r v a l i n h i b i t i o n a t postmortem, changes in the hematocrit, leucocyte counts and d i f f e r e n t i a l leucocyte counts were studied. The e x t r a c t s of mucosal proteins and b i l e s w e r e c o l l e c t e d a t postmortems 6 or 12 WAI. Total serum protein concentrat i o n s , a s well a s protein contents of b i l e and stomach mucosae, were estimated employing the b i u r e t reaction. Electrophoresis on Whatman No. 1 f i l t e r paper, f o r quantitat i v e evaluations of protein f r a c t i o n s in sera, was used. Antibodies were determined in a n t i s e r a , b i l e s and stomach mucosae with hemagglutination and p r e c i p i t a t i o n tests and t o t a l IgG was evaluated by r a d i a l immunodiffusion test a t postmortems. The following r e s u l t s have been obtained: 1. The prepatent period averaged 20 days in r a b b i t s infected with 500 larvae and 29 or 32 days when infected with 10,000 larvae. Prolongation of the prepatent period c o r r e l a t e d with l a r v a l storage a t low temperatures and its - extension a s a consequence of storage a t 4OC.was 3 t o 6 days. 2. Coproscopical examinations have revealed t h a t an inverse r e l a t i o n s h i p between eggs produced per gram of feces and increasing inoculation l e v e l s was observed. Higher egg recoveries occurred in r a b b i t s infected with f r e s h larvae than in those infected with larvae stored a t 4OC. 3 . Postmortem examinations indicated t h a t the e f f e c t i - veness of i n f e c t i o n was c o r r e l a t e d with the dose s i z e of larvae and was not affected by immunomodulation with Cp or CY. In animals exposed t o 500 fresh larvae the e f f e c t i v e n e s s was 66% and in those infected with 10,000 larvae in spring or autumn it was 11.7 or 27.2%, respectively. Also the degree of i n h i b i t i o n in the development depended on the dose s i z e of larvae ( n i l and 3.9 or 2.3%, respectively) . Furthermore, d i s s e c t i o n s t u d i e s indicated t h a t a ”self-cure” reaction, which is manifested by a low percent of i n h i b i t i o n a s wall as prominent decrease in percent of i n h i b i t e d larvae, was observed in the period from the 6th t o the 12th WAI. Addit i o n a l l y , a s i g n i f i c a n t increase in the percentage of inhib i t i o n (45%) was obtained after. immunoactivation with Cp and s i g n i f i c a n t decrease (7.3%) was obtained a f t e r immunosuppression with CY in comparison t o infected untreated controls (26%) .