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Journal of the Kentucky Academy of Science 66(2) 



Figure 1. Protcrometra iiuicroslotna egg developmental stages in adult worms: (A) Stage I, 400X (B) Stage II, 200X 

 (C) Stage III, 200X, and (D) Type III adult, 40X; a = Stage I eggs, b = Stage II eggs, c = Stage III eggs, e = 

 embryo, m = miracidium, v = vitelline material, vg = vitelline granules. 



site, suggested the presence of similar 

 pathology. 



The objectives of this study were (1) to use 

 egg development in adult worms to assess 

 time of P. macrostoma infection in experi- 

 mentally and naturally infected centrarchid 

 fishes and (2) to describe the histopathology 

 associated with infected fishes. 



MATERIALS AND METHODS 



Warmouth (Lepomis gulosus; N = 18), 

 bluegill (Lepomis macrochirus; N = 36), 

 longear sunfish {Lepomis megalotis; N = 45), 

 and infected snails (Elimia semicarinata; N = 

 50) were collected by line (fishes) and hand 

 (snails) during June and July 2002 from North 

 Elkhorn Creek (lat 38° 11' 00" N, long 84° 

 29' 19" W) in Scott County, Kentucky. Fishes 

 were dissected within 4 hours of their collec- 

 tion, and the mean intensity of infection (i.e., 

 average number of worms per infected fish ex- 

 pressed as mean ± SE) and prevalence (i.e., 



percentage of infected hosts) determined for 

 each host species. Wet mounts of all living P. 

 macrostoma adults recovered from the esoph- 

 agus and stomach were examined with a com- 

 pound microscope, and each worm classified 

 as a Type I, Type II, or Type III adult based 

 on the following criteria. Egg stages in adult 

 worms were adopted from Horsfall (1934): (1) 

 Stage I — egg containing a large clear cell at 

 the opercular end and a mass of dark vitelline 

 material at the opposite end (Figure la), (2) 

 Stage II — vitelline mass restricted to a few 

 granules around the periphery of the dividing 

 embryo (Figure lb), and (3) Stage III — shell 

 dark yellow and containing a fully-developed 

 miracidium (Figure Ic). Based on experimen- 

 tal infections of bluegill with P. macrosotma 

 at 24.6°C (Rosen et al. 2000), worms lacking 

 eggs or containing only Stage I eggs were 

 classified as Type I (less than 9 days old), 

 worms with Stage I and II eggs as Type II 

 (between 10 and 17 days old), and worms 



