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.     

Gonadectomy and the development of polycephalic tetrathyridia of Mesocestoides corti (Cestoda: Cyclophyllidea) in mice

The number of polycephalic tetrathyridia present in 150-day-old intraperitoneal larval populations of Mesocestoides corti was markedly increased in mice gonadectomized 1 month prior to infection. This effect was more pronounced in male hosts. In both sexes it was inversely correlated with the size of the populations: the smaller the population, the larger was the number of polycephalic tetrathyridia. These forms are probably produced when the separation of daughter individuals lags behind the growth and organogenesis of these peculiar cestodes.     

Cortisone and the growth of populations of Mesocestoides tetrathyridia in mice.

Volumes and weights of populations of Mesocestoides tetrathyridia increased faster in SEC mice treated with cortisone, than in the controls. Cortisone did not alter the sex resistance of the host and the populations always grew faster in male than in female hosts. Larvae of the populations from cortisone treated mice were smaller than those from control mice, and those from males smaller than those from females.The average size of the larvae decreased as the population size increaed. Fast growing populations contained a higher percentage of larvae with 2 suckers. These forms may serve as indicators of accelerated division of larvae.     

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.     

Gender dependent effects of testosterone and 17β-estradiol on bone growth and modelling in young mice

This study examined the effects of estrogen (17β-estradiol) and testosterone on the growth of long bones in male and female mice, with and without gonadectomy. Weight and nose-to-tail length were determined at 3 weeks of age at time of gonadectomy, 7 days later at the onset of hormone therapy, and throughout the treatment period. Gonadectomized mice exhibited an initial weight gain during the pretreatment period but length was unaffected. Hormone treatment altered weight gain in surgical and intact animals in a gender- and hormone-dependent manner. Estradiol enhanced weight gain in intact mice, but inhibited weight gain in ovariectomized mice. Lower doses of estradiol increased weight gain in orchiectomized mice at early time points. Testosterone increased weight in intact females and males, but not in gonadectomized mice. Estradiol increased nose-to-tail length in intact females at early time points, but inhibited length in ovariectomized females at later times, and it decreased length in intact males. Testosterone increased length in normal females and normal males. Serum Ca was unaffected by ovariectomy, but orchiectomy resulted in decreased levels. Estradiol reduced serum Ca in gonadectomized animals; serum Ca was increased by estradiol treatment in intact females. Changes in tibial bone weight, ash weight and mineral composition, and relative sizes of epiphyseal and metaphyseal bone were gender-, gonadectomy- and hormone-specific. Bone weight was greater in ovariectomized mice. Ash weight per bone was comparable, but there was an increase in Ca and P content with ovariectomy. Estradiol increased bone weight, ash content, and bone Ca and P in ovariectomized and intact females. Orchiectomy alone did not alter bone weight, ash content, or Ca and P, but orchiectomized mice were sensitive to estradiol; all parameters were increased in the orchiectomized animals treated with estradiol. Analysis of the ash content and Ca and P per mg bone, rather than per bone, demonstrated estradiol and testosterone alter net bone formation, but not the amount of mineral per unit bone. Ovariectomy increased hypertrophic cartilage. While estradiol did not alter tibial area in ovariectomized mice, it caused an increase in intact females. The total amount of growth plate cartilage in ovariectomized animals was decreased by estradiol to levels typical of intact animals due to a greater decrease in the hypertrophic cartilage in the ovariectomized mice, as well as a greater increase in metaphyseal bone area. Testosterone had no effect on these parameters in the females. Orchiectomy decreased the amount of growth plate cartilage, but increased the hypertrophic zone. Estradiol increased growth plate cartilage in intact male mice, but decreased it in orchiectomized mice. This difference was also seen in the hypertrophic zone. Total growth plate cartilage and hypertrophic cartilage were increased by testosterone in intact males, whereas metaphyseal and epiphyseal bone area were decreased. The results show for the first time that there is a gender-specific response in both male and female mice to both estradiol and testosterone, whether or not the animals have been gonadectomized. For many parameters, orchiectomized mice behave like females in response to both sex steroids, indicating that the male gonad is needed for mouse bone to exhibit the male phenotypic response to estradiol and testosterone.     

Activation of complement by tetrathyridia of Mesocestoides corti: enhancement by antibodies from infected mice and lack of effect on parasite viability

Tetrathyridia of the cestode Mesocestoides corti were isolated from the peritoneal cavity of infected mice. The parasites activated guinea pig and mouse complement (C) in vitro by both the classical and alternative pathways as shown by quantitative C fixation and crossed immunoelectrophoresis. The ability of tetrathyridia to activate mouse C was enhanced by preincubating the parasites in serum obtained from mice infected with M. corti. Antibodies of the IgG1 class, an immunoglobulin found in profoundly increased amounts in mice infected with M. corti, as well as IgM and IgG2 antibodies, bound to cultured tetrathyridia and facilitated deposition of the third component of C (C3) from dilute mouse serum, presumably via classical pathway activation. The results demonstrate that mouse IgG1 antibodies do not prevent the activation of C by the tetrathyridia or by C-fixing antibodies of other classes which become attached to the tetrathyridia. The activation of C in vitro by tetrathyridia did not affect their ability to grow in mice, even though C3-derived polypeptides could be detected by immunofluorescence on the surface of the parasites.     

Life-history studies on two molecular strains of mesocestoides (Cestoda: Mesocestoididae): identification of sylvatic hosts and infectivity of immature life stages

Life-cycle studies were conducted on 2 molecular strains of Mesocestoides tapeworms that represent different evolutionary lineages (clades A and B). Wild carnivores, reptiles, and rodents were examined for tapeworm infections at 2 enzootic sites: (1) San Miguel Island (SMI), a small island off the coast of southern California and (2) Hopland Research and Extension Center (HREC), a field station in northern California. Results indicate that deer mice (Peromyscus maniculatus) and coyotes (Canis latrans) may play an important role in the life cycles of Mesocestoides (clades A and B) in California. Over half the coyotes at HREC and at least a third of the population of island fox (Urocyon littoralis) at SMI were found to harbor clade A adult Mesocestoides spp. One of every 4 Mesocestoides-infected coyotes had tapeworms representing both clades A and B. Experimental inoculations revealed that proglottids (clades A and B) were not directly infectious to rodents, reptiles, or dogs. On the other hand, mice, lizards, and hamsters fed tetrathyridia of Mesocestoides spp. (clades A or B) developed peritoneal tetrathyridial infections. A dog that was fed tetrathyridia (clade B) developed an adult tapeworm infection. Acephalic metacestodes given orally to western fence lizards, laboratory mice, or domestic dogs did not result in metacestode or adult tapeworm infections. Whereas most clade A acephalic metacestodes from dogs were asexually proliferative, clade A tetrathyridia isolated from wild deer mice did not show evidence of asexual replication. Our study supports the hypothesis that a second, as of yet unidentified, intermediate host is necessary to complete the life cycles of Mesocestoides spp., and that acephalic metacestodes represent an aberrant form, incapable of further development.     

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.     

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.     

Molecular systematics of Mesocestoides sPP (cestoda: mesocestoididae) from domestic dogs (Canis familiaris) and coyotes (Canis latrans)

The genus Mesocestoides Vaillant, 1863 includes tapeworms of uncertain phylogenetic affinities and with poorly defined life histories. We previously documented 11 cases of peritoneal cestodiasis in dogs (Canis familiaris L.) in western North America caused by metacestodes of Mesocestoides spp. In the current study, DNA sequences were obtained from metacestodes collected from these dogs (n = 10), as well as proglottids from dogs (n = 3) and coyotes (Canis latrans Say, 1823 [n = 2]), and tetrathyridia representing laboratory isolates of M. corti (n = 3), and these data were analyzed phylogenetically. Two nuclear genetic markers, 18S ribosomal DNA and the second internal-transcribed spacer (ITS 2), were sequenced. Phylogenetic analysis of the 18S rDNA data recovered a monophyletic group composed of all samples of Mesocestoides spp., distinct from closely related outgroup taxa (Amurotaenia Akhmerov, 1941 and Tetrabothrius Rudolphi, 1819). Initial analysis of the ITS 2 data resolved 3 clades within Mesocestoides. Two proglottids from dogs formed a basal clade, a second clade was represented by tetrathyridial isolates, and a third clade included all other samples. Interpretation of these data from an apomorphy-based perspective identified 6 evolutionary lineages. We also assessed whether metacestodes from dogs (n = 4) are capable of asexual proliferation in laboratory mice. One tetrathyridial and 2 acephalic isolates from dogs proliferated asexually. Further investigation is warranted to determine which of the lineages represent distinct species and to determine the life history strategies of Mesocestoides spp.     

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.     

Circulating antigens in infections of mice by tetrathyridia of Mesocestoides corti Hoeppli, 1925

Two circulating antigens were detected in the serum of ICR/Timco female mice infected intraperitonealy with tetrathyridia of the cestode Mesocestoides corti Hoeppli, 1925. One circulating antigen appeared by day 2 postinfection (p.i.) and remained in all mice until at least 90 days p.i. A second antigen appeared in the serum on day 14 p.i. and disappeared from all mice by day 28 p.i. Infected mouse serum also contained antibodies against one secretory/excretory antigen and two antigens in crude homogenate, as judged by double diffusion in two dimensions (Ouchterlony). Immune deposits were observed in the kidney tissue of Rockland mice by transmission electron microscopy, and their identity as products of tetrathyridia was confirmed by immunofluorescence. Further studies showed that the main antibody subclass associated with the mesangial immune deposits was 7S gamma l, and that other subclasses of IgG and IgM were not involved. Antigen was found in the proximal renal tubules of infected mice, as demonstrated by fluorescein-labeled IgG fraction of rabbit antitetrathyridia secretory/excretory antigen antisera. The presence of tetrathyridia antigen in the urine of infected mice was confirmed using the Ouchterlony technique.     

Perinatal anti-androgen treatment and genotype affect the mesotelencephalic dopamine system and behavior in mice

Sex and strain differences in tyrosine hydroxylase activity (TH) of brain dopamine systems have been reported for mice. To investigate if there might be a causal relationship between perinatal androgen secretion and regional mesotelencephalic TH activity, BALB/cJ and C57BL/6ByJ male mice were treated perinatally with cyproterone, a steroidal anti-androgen (or vehicle), and orchiectomized at 1 month of age. Two-way analysis of variance indicated significant treatment and strain effects in the mesencephalon and tuber olfactorium: perinatal cyproterone treatment lowered TH activity, and BALB/cJ had higher regional TH activities than those of C57BL/6ByJ. The most prominent behavioral effects of cyproterone treatment were found in the expression of scratching, which was considerably increased in both strains. Possible implications of these results are discussed.     

Some enzymes of carbohydrate metabolism in Mesocestoides corti and Heterakis spumosa

The activities of selected enzymes of carbohydrate metabolism were measured in tetrathyridia of Mesocestoides corti and in adult females and males of Heterakis spumosa. When the species were compared, only lactate dehydrogenase and phosphoenolpyruvate carboxykinase activities were considerably higher in M. corti. Activities of other enzymes were higher in H. spumosa, with malate dehydrogenase activity being considerably so. In H. spumosa, enzyme activity was higher, and succinate dehydrogenase markedly so in males, when compared with females. Tetrathyridia aged 170 and 210 days show relatively stable malate and lactate dehydrogenase activities, and mice of ICR and BALB/c strains are suitable for the maintenance of tetrathyridia.     

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.     

Tetrathyridia of Mesocestoides lineatus in Chinese Snakes and Their Adults Recovered from Experimental Animals

Morphological characteristics of Mesocestoides lineatus tetrathyridia collected from Chinese snakes and their adults recovered from experimental animals were studied. The tetrathyridia were detected mainly in the mesentery of 2 snake species, Agkistrodon saxatilis (25%) and Elaphe schrenckii (20%). They were 1.73 by 1.02 mm in average size and had an invaginated scolex with 4 suckers. Adult tapeworms were recovered from 2 hamsters and 1 dog, which were orally infected with 5-10 larvae each. Adults from hamsters were about 32 cm long and those from a dog were about 58 cm long. The scolex was 0.56 mm in average width with 4 suckers of 0.17 by 0.15 mm in average size. Mature proglottids measured 0.29 by 0.91 mm (av.). Ovaries and vitellaria bilobed and located in the posterior portion of proglottids. The cirrus sac was oval-shaped and located median. Testes were follicular, distributed in both lateral fields of proglottids, and 41-52 in number per proglottid. Gravid proglottids were 1.84 by 1.39 mm (av.) with a characteristic paruterine organ. Eggs were 35 by 27 µm in average size with a hexacanth embryo. These morphological characteristics of adult worms were identical with those of M. lineatus reported previously. Therefore, it has been confirmed that the tetrathyridia detected in 2 species of Chinese snakes are the metacestodes of M. lineatus, and 2 snake species, A. saxatilis and E. schrenckii, play the role of intermediate hosts.     

Normal and aberrant Mesocestoides tetrathyridia from Crocidura spp. (Soricimorpha) in Corsica and Spain

Tetrathyridia of Mesocestoides sp. were collected from the body cavities of the shrews (Insectivora), Crocidura russula, in Valencia, Spain and Crocidura suaveolens on the Mediterranean island of Corsica, France. Specimens were processed by routine microscopic and histological techniques, including examination with brightfield, phase-contrast, and differential-interference-contrast optics. Most tetrathyridia were clustered together inside host-derived fibrotic capsules, but some occurred free in the body cavity. All specimens examined from both locations had solid hindbodies, i.e., lacking a primary lacuna, thus conforming to the plerocercoid metacestode type; all possessed a single normal tetra-acetabulate scolex. All metacestodes from C. russula in Valencia were normal tetrathyridia. Those from C. suaveolens in Corsica were either normal tetrathyridia or had aberrant deep convolutions of an unusually elongated hindbody. No tetrathyridium from either location or host showed tegumental or excretory duct anomalies such as those reported by several authors from aberrant tetrathyridia and spargana in some other locations. No definitive evidence of asexual proliferation was visible in any of the tetrathyridia, but those with abnormally convoluted hindbodies from a single C. suaveolens in Corsica suggest the potential for asexuality by fission of the hindbody. These results add to our understanding of morphological and developmental variation among metacestodes in this widespread and variable genus.     

Occurrence of tetrathyridia of Mesocestoides sp. (Cestoidea: Cyclophyllidea) in North American anurans (Amphibia)

A new host and geographic locality record is reported for tetrathyridia of Mesocestoides sp. in two species of ranid frogs (Rana berlandieri and R. pipiens) from Texas and New York, respectively. Tetrathyridia were found encapsulated in liver and mesenteries of the hosts. Morphological examination and experimental inoculation of these tetrathyridia into mice demonstrated the absence of capacity for asexual proliferation. Overall prevalence of infection was low in anurans from Arkansas, Texas and New York, but intensities can be generally high. In addition, a summary of frogs and toads from North America reported as hosts of tetrathyridia of Mesocestoides sp. is presented.     

Effects of mebendazole and levamisole on tetrathyridia of Mesocestoides corti in the mouse

Bennet E.-M., Behm C.A. and Bryant C. 1978. Effects of mebendazole and levamisole on tetrathyridia of Mesocestoides corti in the mouse. International Journal for Parasitology8: 463–466. Mebendazole, but not levamisole, administered to mice carrying artificial infections of 50 tetrathyridia of Mesocestoides corti, was effective in killing the parasites. However, simultaneous administration of mebendazole and levamisole was still more effective. Treatment with levamisole before infection had no additional effect.Injection of mice with dead larvae offered some protection against a subsequent challenge with 50 live larvae; however, levamisole did not then improve the anthelmintic efficacy of mebendazole. In mice rendered immunoincompetent by radiation mebendazole was less effective than in non-irradiated controls and levamisole again did not enhance the effect of mebendazole. It is concluded that anthelmintic efficacy of mebendazole depends on its anthelmintic activity supplemented by the host's immune response; and that levamisole stimulates the latter.     

Factors influencing the establishment of Mesocestoides corti in mice following oral inoculation of tetrathyridia

Factors which influence the establishment of tetrathyridia of Mesocestoides corti in mice following inoculation per os were examined. Only a proportion of the tetrathyridia penetrate the gut wall and gain access to the peritoneal cavity and liver, and most of these penetrate through the wall of the small intestine. It appears that tetrathyridia must attach to the intestinal mucosa and commence penetration immediately or they pass into the large intestine and are voided. Establishment was not influenced by strain, sex or age of host. However, the temperature at which tetrathyridia were maintained before inoculation influence their ability to penetrate the intestinal wall. Additionally it appears that tetrathyridia have to undergo a morphological change before or during, this penetration phase.