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Prenatal development of calbindin D-28K in human visual cortex
1Department of Anatomy and Neurobiology, Hunan Medical University, Changsha, Hunan, People's Republic of China.
Insights
Calbindin D-28K (CB) expression in the human fetal visual cortex shows transient patterns before full development. This calcium-binding protein appears early and changes distribution as the cortex matures.
Area of Science:
- Neuroscience
- Developmental Biology
- Neuroanatomy
Background:
- Calbindin D-28K (CB) is a calcium-binding protein.
- Its role and distribution during human cortical development are not fully understood.
Purpose of the Study:
- To investigate the spatiotemporal distribution of CB in the human fetal primary visual cortex.
- To understand the developmental timeline and transient expression of CB.
Main Methods:
- Immunohistochemical analysis of human fetal brain tissue.
- Microscopic examination of CB distribution across cortical layers and developmental stages.
Main Results:
- CB is detected early in Cajal-Retzius cells and sparse neurons in ventricular/intermediate zones by 15 weeks gestation.
- CB expression emerges in deeper cortical layers (II-VI) from 26 weeks, progressing in an inside-out manner.
- CB labeling patterns shift, with transient expression in some layers and distinct localization in primary visual cortex by term.
Conclusions:
- CB expression is precocious, preceding complete laminar differentiation of the visual cortex.
- Some CB expression patterns are transient, highlighting dynamic developmental processes.
- CB distribution provides insights into the maturation of the human fetal visual cortex.
Abstract:
The distribution of the calcium-binding protein calbindin D-28K (CB) was investigated in human fetal primary visual cortex. CB is present in Cajal-Retzius cells of layer I, in sparse neurons of the ventricular and intermediate zones (VZ, IZ), and in tangential fibres in IZ by 15 weeks (W) of gestation. Cajal-Retzius cells lose their staining by 30W. CB appears in layers II-VI mainly from 26W, following an inside-outside sequence. Until 34W, CB labelling is in somata and neuropil located primarily in layers IVA, IVC and V. Then reactive perikarya and puncta increase in layers II-IVA and deep IVB and C, but are reduced in infragranular layers from 34W to term. From 30W positive somata form clusters in the cell-rich bands in layers IV and V and labelled neuropil in layers III and IV has a periodic pattern from 34W. Also from 34W, numerous lightly reactive pyramidal cells are present in layers II to IVA in primary, but not secondary, visual cortex. Our results show precocious expression of CB before full laminar differentiation of the cortex and that some of this expression is transient.