Subplate Zone of the Human Brain: Historical Perspective and New Concepts

Subplate zone (SP) is prominent, transient laminar compartment of the human fetal cerebral wall. The SP develops around 13 and gradually disappears after 32–34 postovulatory weeks. The SP neurons can be found as late as nine postnatal months, while remnants of the SP neurons can be traced until adult age in the form of interstitial neurons of the gyral white matter. SP is composed of postmigratory and migratory neurons, growth cones, loosely arranged axons, dendrites, glial cell and synapses. The remarkable feature of the SP is the presence of large amount of extracellular matrix. This feature can be used for delineation of SP in magnetic resonance images (MRI) of both, in vivo and post mortem brains. The importance of SP as the main synaptic zone of the human fetal cortex is based on the rich input of »waiting« afferents from thalamus and cortex, during the crucial phase of cortical target area selection. SP increases during mammalian evolution and culminates in human brain concomitantly with increase in number and diversity of cortico-cortical fibers. The recent neurobiological evidence shows that SP is important site of spontaneous endogeneous activity, building a framework for development of cortical columnar organization. The SP, which can be readily visualized on conventional and DTI (diffusion-tensor-imaging) MRI in vivo, today is in the focus of interest of pediatric neurology due to the following facts: (1) SP is the site of early neural activity, (2) SP is the major substrate for functional plasticity, and (3) selective vulnerability of SP may lead to cognitive impairment

Primate-Specific Origins and Migration of Cortical GABAergic Neurons

Gamma-aminobutyric-acidergic (GABAergic) cells form a very heterogeneous population of neurons that play a crucial role in the coordination and integration of cortical functions. Their number and diversity increase through mammalian brain evolution. Does evolution use the same or different developmental rules to provide the increased population of cortical GABAergic neurons? In rodents, these neurons are not generated in the pallial proliferative zones as glutamatergic principal neurons. They are produced almost exclusively by the subpallial proliferative zones, the ganglionic eminence (GE) and migrate tangentially to reach their target cortical layers. The GE is organized in molecularly different subdomains that produce different subpopulations of cortical GABAergic neurons. In humans and non-human primates, in addition to the GE, cortical GABAergic neurons are also abundantly generated by the proliferative zones of the dorsal telencephalon. Neurogenesis in ventral and dorsal telencephalon occurs with distinct temporal profiles. These dorsal and ventral lineages give rise to different populations of GABAergic neurons. Early-generated GABAergic neurons originate from the GE and mostly migrate to the marginal zone and the subplate. Later-generated GABAergic neurons, originating from both proliferative sites, populate the cortical plate. Interestingly, the pool of GABAergic progenitors in dorsal telencephalon produces mainly calretinin neurons, a population known to be significantly increased and to display specific features in primates. We conclude that the development of cortical GABAergic neurons have exclusive features in primates that need to be considered in order to understand pathological mechanisms leading to some neurological and psychiatric diseases

The Role of Croatia in the Management of the Humanitarian Crisis in Bosnia and Herzegovina

Croatia played a crucial role in the management and termination of the humanitarian crisis caused by the aggression of the Yugoslav Army and Serbian paramilitary forces in Bosnia and Herzegovina. Between 1992 and 1995, Croatia accepted three waves of refugees and cared for more than 500,000 refugees from B&H; it thus secured the basic precondition for the survival of B&H as a state. Croatia invested more than 1,000,000.000 U.S. dollars from its State budget just for the care of refugees from B&H. Even today about 130,000 Bosnian refugees are still accomodated in Croatia, for most are still unable to return to their homes. The European Community and the UN were unable to protect the lives of civilians or to prevent grave breaches of international humanitarian law. At the some time, the Croatian military operation "Storm" in 1995 saved the lives of thousands of civilians in the Bihać area. A careful analysis of the Croatian contribution to the achievement of the Dayton agreements and the resolution of the humanitarian crisis in B&H clearly reveals that the positive role of Croatia has been seriously underestimated and down-played by the international community

Jelena Krmpotić-Nemanić (1921–2008): Contributions to Human Neuroanatomy

Jelena Krmpoti}-Nemani} (1921–2008) was a world-famous anatomist, internationally distinguished otolaryngologist, a member of the Croatian Academy of Sciences & Arts and appreciated professor at the School of Medicine University of Zagreb. The founding influence in her scientific career came from her mentor Drago Perovi} who was a student of Ferdinand Hochstetter, the leading authority in the field of human developmental neuroanatomy and embryology. Such an influence was obviously important in early shaping of the research agenda of Jelena Krmpoti}-Nemani}, and it remains important in a long series of studies on developing human telencephalon initiated by Ivica Kostovi} and his collaborators – with an always present and active support of Jelena Krmpoti}-Nemani}. The aim of this mini review is to briefly describe her numerous contributions to the anatomy of the human peripheral and central nervous system

Transient Cellular Structures in Developing Corpus Callosum of the Human Brain

The corpus callosum connects two cerebral hemispheres as the most voluminous fiber system in the human brain. The developing callosal fibers originate from immature pyramidal neurons, grow through complex pathways and cross the midline using different substrates in transient fetal structures. We analyzed cellular structures in the human corpus callosum on postmortem brains from the age of 18 weeks post conception to adult, using glial fibrillary acidic protein, neuron- specific nuclear protein, and chondroitin sulphate immunocytochemistry. We found the presence of transient cellular structures, callosal septa, which divide major fiber bundles and ventrally merge with subcallosal zone forming grooves for callosal axons. The callosal septa are composed of glial fibrillary acidic protein reactive meshwork, neurones and the chondroitin sulphate immunoreactive extracellular matrix. The developmental window of prominence of the callosal septa is between 18-34 weeks post conception which corresponds to the period of most intensive growth of callosal axons in human. During the early postnatal period the callosal septa become thinner and shorter, lose their neuronal and chondroitin sulphate content. In conclusion, transient expression of neuronal, glial and extracellular, growing substrate in the callosal septa, as septa itself, indicates their role in guidance during intensive growth of callosal fibers in the human brain. These findings shed some light on the complex morphogenetic events during the growth of the corpus callosum and represent normative parameters necessary for studies of structural plasticity after perinatal lesions