Gonadectomy,sex hormones and the growth of tetrathyridial populations of Mesocestoides corti (Cestoda: Cyclophyllidea) in mice

Gonadectomy in mice considerably depressed the volumes of intraperitoneal tetrathyridial populations, orchiectomy being more efficient than ovariectomy. Testosterone propionate accelerated the growth of tetrathyridial populations in gonadectomized mice of both sexes. Oestradiol benzoate was less efficient, but considerably increased the invasion of livers both in intact and in gonadectomized mice. The average size of tetrathyridia was inversely proportional to the size of the populations: tetrathyridia from an orchiectomized mouse were the largest, those from an orchiectomized and testosterone treated mouse, the smallest, and those from an orchiectomized mouse treated with oestradiol, intermediate in size.     

Effect of sex hormones on the growth and multiplication of tetrathyridia of Mesocestoides corti (Cestoda: Cyclophyllidea) in mice

The number of tetrathyridia in the peritoneal cavities of mice increases exponentially with time. Thirty days post infection more larvae are in the cavities than in the livers. After that the increase of intraperitoneal populations continues, whereas the number of tetrathyridia in the livers remains more or less constant.Exogenous testosterone propionate, 10 $\text{μg}\text{g}$, twice a week, for 5 weeks, increases significantly the total volumes of tetrathyridial populations in the peritoneal cavities, whereas oestradiol benzoate, 5 $\text{μg}\text{g}$ or 10 $\text{μg}\text{g}$, also for 5 weeks, accelerates the rate of growth and multiplication of coelomic tetrathyridia to a much lesser extent, but increases significantly the infection of the livers.     

Mesocestoides corti in the rat: Comparisons of Mesocestoides corti infections in rats and mice

Infections of M. corti in rats were compared with those in mice. The recoveries of parasites and their distribution were examined for 60 days after infection. During this period continuous and extensive multiplication occurred in mice. In rats there was an initial multiplication of tetrathyridia in the first 10 days followed by a decline in numbers. The relative distribution of tetrathyridia between the peritoneal cavity and liver was similar in both hosts.     

Histopathological changes in livers of mice infected with tetrathyridia of Mesocestoides corti and exposed to different environmental temperatures

Novak M. 1982. Histopathological changes in livers of mice infected with tetrathyridia of Mesocestoides corti and exposed to different environmental temperatures. International Journal for Parasitology12: 41–45. Observations on the histopathology of the liver of mice infected with Mesocestoides corti and kept for 20 days p.i. (post-infection) at low (5 ± 1°C), room (21 ± 1°C) or high (35 ± 1°C) temperature revealed that the degree of liver pathology was directly proportional to the intensity of liver infection, which in turn was the result of the temperature effect. The most severe pathological changes occured in the heavily infected organs of mice kept at low temperature, followed by less prominent changes in moderately infected livers of mice kept at room temperature and the smallest changes in lightly infected livers of mice kept at high temperature. The pathological changes in infected and uninfected livers of hosts exposed to different environmental temperatures are described and compared.     

Effects of certain lipid compounds on growth and asexual multiplication of Mesocestoides corti (Cestoda) tetrathyridia

The effects of Williams and Law mixture (W-L), farnesol (juvenile hormone mimics), ecdysterone (molting hormone analog), cholesterol, and stigmasterol on growth and asexual reproduction of Mesocestoides corti larvae in vivo and in vitro were studied. W-L and ecdysterone stimulated an increase in larval asexual reproduction under in vivo conditions, however, cholesterol had no effect on the larvae in vivo. In vitro, cholesterol stimulated a slight increase in reproduction but had no effect on growth; stigmasterol appeared to be somewhat detrimental to the larvae. In vitro, W-L, farnesol, and ecdysterone stimulated by varying amounts an increase in growth (as measured by larval size) and asexual reproduction. Lipid extraction of M. corti larvae and Hymenolepis diminuta adults, followed by a series of thin-layer chromatograms, yielded 2 compounds (I-B and I-D) which affected M. corti larvae in vitro. These 2 compounds stimulated increased growth of the M. corti larvae and to some extent an increase in asexual reproduction.     

Spontaneous sexual differentiation of Mesocestoides corti tetrathyridia in vitro

Barrett N. J., Smyth J. D. and Ong S. J. 1982. Spontaneous sexual differentiation of Mesocestoides corti tetrathyridia in vitro. International Journal for Parasitology12: 315–322. Tetrathyridia of Mesocestoides corti, from the body cavity of mice, maintained in the laboratory by intraperitoneal infection, were used for in vitro culture. In an initial experiment, after 50 days asexual multiplication in vitro one tetrathyridium spontaneously segmented and developed into a sexually mature adult. Further experiments were carried out in an attempt to determine the conditions favouring segmentation and sexual differentiation. A combination of 5 or 10 ml liquid medium S1OE.H (basically composed of CMRL 1066 and foetal calf serum with supplements) changed every 3 days, in a Leighton tube (19 × 105 mm), rotated at 38°C and gassed with 10 or 20% CO₂, containing between 100 and 200 tetrathyridia, has proved to be most suitable so far. Numerous adult worms with normal male and female genitalia have been obtained in this system. However, segmentation is sporadic, rather than consistent and only a few shelled eggs with hooked oncospheres have so far been obtained, suggesting that impregnation and fertilization in vitro is not fully comparable with that in vivo.     

Localization and associated histopathology of asexually proliferative Mesocestoides corti tetrathyridia (cestoda) infecting mouse mammary glands

Female mice of pregnant random-bred, or unmated BALB/c groups were exposed per os to Mesocestoides corti tetrathyridia and necropsied at various intervals postexposure. The right posterior subcutaneous fat pad with two mammary glands was removed from each mouse, stained, mounted whole and examined microscopically for localization of worms. The left fat pad/gland set was processed, sectioned and stained using standard histological techniques. In pregnant mice, tetrathyridia were localized primarily in the fat pad's posteroventral lobe. Unmated mice had few worms in the mammary glands or associated fat pads. The difference in infection levels between the two host groups may result from mouse strain difference or the pregnant condition of one group.     

In vitro development of the strobilar stage of Mesocestoides corti

Thompson R. C. A., Jue Sue L. P. and Buckley S. J. 1982. In vitro development of the strobilar stage of Mesocestoides corti. International Journal for Parasitology12: 303–314. Sexually mature strobilated adults of Mesocestoides corti were grown consistently from undifferentiated tetrathyridia in vitro using a conventional diphasic culture system. Development (growth, strobilisation and maturation) was compared in vitro and in vivo. Although growth and strobilisation were comparable in vitro and in vivo, during the first 18 days, total length and numbers of proglottids decreased in vivo but continued to increase in vitro after day 18. Both male and female reproductive systems appeared to develop normally in vitro and self copulation was frequently observed in cultured worms. However, fully developed oncospheres were not produced in vitro.     

A comparative study of the susceptibility of inbred strains of mice to infection with Mesocestoides corti

White T. R., Thompson R. C. A. and Penhale W. J. 1982. A comparative study of the susceptibility of inbred strains of mice to infection with Mesocestoides corti. International Journal for Parasitology12: 29–33. The susceptibility of 6 strains of inbred mice to infection with Mesocestoides corti was studied following both intraperitoneal and oral inoculation of tetrathyridia. The greatest degree of resistance was seen in C57BL/6 mice and this resistance was independent of route of inoculation. The proliferation of the parasite in C57BL/6 mice was compared with a more susceptible strain (CBA/H) on 7, 14, 21, 35 and 60 days post-infection. Although both strains harboured significantly different parasite burdens during the initial period following infection, these differences were no longer apparent by day 60.     

Cross-protection between the metacestodes of Mesocestoides corti and Taenia crassiceps in mice

Novak M. 1984. Cross-protection between the metacestodes of Mesocestoides corti and Taenia crassiceps in mice. International Journal for Parasitology14: 497–501. Infection with M. corti generated significant resistance against a challenge with T. crassiceps introduced either 2 or 6 weeks after primary infection. Challenge infection with T. crassiceps did not influence primary infection with M. corti. Infection with T. crassiceps protected significantly against challenge with M. corti given 2 weeks but not 6 weeks after the primary infection. Challenge infection with M. corti significantly suppressed primary infection with T. crassiceps.     

Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX

Toye P. G. and Jenkin C. R. 1982. Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX. International Journal for Parasitology12: 399–402. Zymosan and Salmonella enteritidis 11RX were found to partially protect mice against infection with the cestode Mesocestoides corti. Thus, mice previously infected with S. enteritidis 11RX contained fewer parasites in the peritoneal cavity compared to normal mice. Mice pretreated with zymosan contained fewer parasites in the peritoneal cavity and in the liver compared to normal mice and this protection was enhanced by the passive transfer of serum from mice chronically infected with M. corti. Examination of mice in the initial stages of infection revealed that the administration of zymosan led to an alteration in parasite location from the peritoneal cavity to the liver.     

Acceleration of the growth of tetrathyridial populations of Mesocestoides Corti (Cestoda: Cyclophyllidea) by splenectomy

Acceleration of the growth of tetrathyridial populations of Mesocestoides corti (Cestoda: Cyclophyllidea) by splenectomy. International Journal for Parasitology4, 165–168. Experiments with LDF₁ hybrid mice showed that splenectomy 7 days prior to infection, increases the total biomass of tetrathyridial populations of Mesocestoides corti in hosts of both sexes.This increase is accompanied by a decrease in the size of individuals, and by an increase in the percentage of two-suckered and acephalic forms. Splenectomy thus accelerates both the growth of the biomass of populations and the asexual multiplication of the tetrathyridia.     

Mesocestoides corti in the rat: The cellular response in the peritoneal cavity of rats infected with Mesocestoides corti

The tetrathyridium (second larval stage) of Mesocestoides corti elicits an extensive cellular response in the peritoneal cavity of rats which was monitored over a period of 40 days following infection. The total white cell count of female Wistar rats rose in the peritoneal cavity during the first 10 days of infection, then declined slowly. Eosinophilia was characteristic, as it is in most helminth infections. Cellular adherence to the surface of some tetrathyridia was noted. In rats infected with a large number of tetrathyridia, many parasites were found trapped in the mesenteries.     

Environmental temperature and the growth of Mesocestoides corti populations in mice

The volumes of tetrathyridial populations in the peritoneal cavities of mice of both sexes kept at 5 ± 1dgC for 20 days were significantly larger than those in control mice kept at 21 ± 1dgC; the volumes of these populations in mice kept at 35 ± 1dgC were significantly lower in males but not in females. The liver weights in different groups were proportional to the intensity of liver infection: for both sexes livers were heaviest at 5 ± 1dgC and lightest at 35 ± 1dgC.     

Maternal transmission of asexually proliferative Mesocestoides corti tetrathyridia (Cestoda) in mice

Asexually proliferative Mesocestoides corti tetrathyridia were studied to test the hypothesis of in utero transmission in mice and define more clearly the path of transmammary transmission. In utero transmission was not observed in 132 fetuses (22 litters) taken by caesarean section from infected mothers. However, 19 of these mothers had tetrathyridia in their mammary glands at the time of operation, nine had worms in the uterine lumen, and one had a single worm in the maternal blood space of a placenta. No tetrathyridia were found in amniotic cavities. No infection was found in 32 young (7 litters) examined immediately after birth to infected mothers, but before nursing. No infection was found in 30 young (5 litters) removed from infected mothers before nursing and raised by uninfected fosters. Of 29 uninfected young (5 litters) allowed to nurse on infected mothers, 18 became infected. Whole mounts and sections of infected mammary glands showed proliferating tetrathyridia free in larger milk ducts and free and encapsulated in mammary parenchyma. These data suggest that maternal transmission of M. corti tetrathyridia in mice occurs primarily or perhaps exclusively by the transmammary route.