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Background: Neocortex development has been extensively studied in altricial rodents such as mouse and rat. Identification of alternative animal models along the "altricial-precocial" spectrum in order to better model and understand neocortex development is warranted. The Greater cane rat (GCR, Thyronomys swinderianus) is an indigenous precocial African rodent. Although basic aspects of brain development in the GCR have been documented, detailed information on neocortex development including the occurrence and abundance of the distinct types of neural progenitor cells (NPCs) in the GCR are lacking. Methods: GCR embryos and fetuses were obtained from timed pregnant dams between gestation days 50–140 and their neocortex was analyzed by immunofluorescence staining using characteristic marker proteins for NPCs, neurons and glia cells. Data were compared with existing data on closely related precocial and altricial species, i.e. guinea pig and dwarf rabbit. Results: The primary sequence of neuro- and gliogenesis, and neuronal maturation is preserved in the prenatal GCR neocortex. We show that the GCR exhibits a relatively long period of cortical neurogenesis of 70 days. The subventricular zone becomes the major NPC pool during mid-end stages of neurogenesis with Pax6 + NPCs constituting the major basal progenitor subtype in the GCR neocortex. Whereas dendrite formation in the GCR cortical plate appears to initiate immediately after the onset of neurogenesis, major aspects of axon formation and maturation, and astrogenesis do not begin until mid-neurogenesis. Similar to the guinea pig, the GCR neocortex exhibits a high maturation status, containing neurons with well-developed dendrites and myelinated axons and astrocytes at birth, thus providing further evidence for the notion that a great proportion of neocortex growth and maturation in precocial mammals occurs before birth. Conclusions: Together, this work has deepened our understanding of neocortex development of the GCR, of the timing and the cellular differences that regulate brain growth and development within the altricial–precocial spectrum and its suitability as a research model for neurodevelopmental studies. The timelines of brain development provided by this study may serve as empirical reference data and foundation in future studies in order to model and better understand neurodevelopment and associated alterations. [ABSTRACT FROM AUTHOR]

Background: Toxoplasma gondii is an obligate intracellular parasite with a worldwide distribution. Congenital infection in humans and animals may lead to severe symptoms in the offspring, especially in the brain. A suitable animal model for human congenital toxoplasmosis is currently lacking. The aim of this study is to establish and validate the guinea pig as a model for human congenital toxoplasmosis by investigating the impact of the T. gondii infection dose, the duration of infection and the gestational stage at infection on the seroconversion, survival rate of dams, fate of the offspring, T. gondii DNA loads in various offspring tissues and organs and the integrity of the offspring brain. Methods: Pregnant guinea pigs were infected with three different doses (10, 100, 500 oocysts) of T. gondii strain ME49 at three different time points during gestation (15, 30, 48 days post-conception). Serum of dams was tested for the presence of T. gondii antibodies using immunoblotting. T. gondii DNA levels in the dam and offspring were determined by qPCR. Offspring brains were examined histologically. Results: We found the survival rate of dams and fate of the offspring to be highly dependent on the T. gondii infection dose with an inoculation of 500 oocysts ending lethally for all respective offspring. Moreover, both parameters differ depending on the gestational stage at infection with infection in the first and third trimester of gestation resulting in a high offspring mortality rate. The duration of infection was found to substantially impact the seroconversion rate of dams with the probability of seroconversion exceeding 50% after day 20 post-infection. Furthermore, the infection duration of dams influenced the T. gondii DNA loads in the offspring and the integrity of offspring brain. Highest DNA levels were found in the offspring brain of dams infected for ≥ 34 days. Conclusion: This study contributes to establishing the guinea pig as a suitable model for human congenital toxoplasmosis and thus lays the foundation for using the guinea pig as a suitable animal model to study scientific questions of high topicality and clinical significance, which address the pathogenesis, diagnosis, therapy and prognosis of congenital toxoplasmosis. [ABSTRACT FROM AUTHOR]