U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            SPEER, C - U TENNESSEE,KNOXVILLEitem
                                            Dubey, Jitender
  Submitted to: International Journal for Parasitology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 11/3/2004
                                    Publication  Date: 2/15/2005
                                    Citation: Speer, C.A., Dubey, J.P. 2005. Ultrastructural differentiation of Toxoplasma gondii schizonts (types b to e) and gamonts in the intestines of cats fed bradyzoites. International Journal for Parasitology. 35:193-206.Interpretive Summary: Infection by the single-celled parasite Toxoplasma gondii causes mental retardation in children and abortion in livestock.  Cats are the main reservoirs of infection.  Scientists at the Beltsville Agricultural Research Center and the University of Tennessee report for the first time ultrastructure of Toxoplasma in the intestines of cats.  These results will be of interest to biologists and parasitologists.
                                Technical Abstract:  The ultrastructural characterisitics of four types of Toxoplasma gondii schizonts (types B, C, D and E) and their merozoites, microgamonts and macrogamonts were compared in cats killed at days 1, 2, 4 and 6 days after feeding tissues cysts from the brains of mice.  Schizonts, merozoites and gamonts contained most of the ultrastructural features characteristic of the phylum Apicomplexa.  All four types of schizonts developed within enterocytes or intraepithelial lymphocytes.  Occasionally, type B and C schizonts developed within enterocytes that were displaced beneath the epithelium into the lamina propria.  Type D and E schizonts and gamonts developed exclusively in the epithelium.  Tachyzoites occurred exclusively within the lamina propria.  Type B schizonts formed merozoites by endodyogeny, whereas types C-E developed by endopolygeny. The parasitophorous vacuoles surrounding type B and C schizonts consisted of a single membrane, whereas those surrounding types D and E schizonts were comprised of 2 to 4 electron-dense membranes. The parasitophorous vacuole of type B schizonts had an extensive tubulovesicular membrane network (TMN); the TMN was reduced or absent in type C schizonts and completely absent in types D and E schizonts and gamonts.  Type B merozoites were ultrastructurally similar to tachyzoites, except that they were slightly larger.  Type C merozoites exhibited a positive periodic acid-Schiff reaction by light microscopy and ultrastructurally contained amylopectin granules. Rhoptries were labyrinthine in type B merozoites but were electron-dense in types C-E.  The early development of microgamonts, macrogamont and oocysts is also described.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov