Distribution of Cadherin in the Parahippocampal Area of Developing Domestic Chicken Embryos

Abstract

Hippocampal formation is important in spatial learning and memory. Members of the cadherin superfamily are observed in the neural system with diverse spatial and temporal expression patterns and are involved in many biological processes. To date, the avian hippocampal formation is not well understood. In this study, we examined the expression of cadherin mRNA in chicken and mouse brains to investigate the morphological and cytoarchitectural bases of hippocampal formation. Profiles of the spatiotemporal expression of cadherin mRNAs in the developing chicken embryonic parahippocampal area (APH) are provided, and layer-specific expression and spatiotemporal expression were observed in different subdivisions of the APH. That fact that some cadherins (Cdh2, Cdh8, Pcdh8 and Pcdh10) showed conserved regional expression both in the hippocampus and entorhinal cortex of mice and the hippocampal formation of chickens partially confirmed the structural homology proposed by previous scientists. This study indicates that some cadherins can be used as special markers of the avian hippocampal formation.

Keywords: Avian; Cadherin; Chicken embryos; Hippocampus; Parahippocampal area.

Fig. 1

Schematic illustration of subdivisions respectively in the pigeon hippocampal formation (A) and chicken embryo brain (B) [2, 11].

Fig. 2

Schematic illustration of E14 and E18 chicken embryo brain. (A) Embryos at intermediate development stage E14. (B) Embryos at late development stage E18. HP, hippocampus; APHm, the medial part of APH; APHi, the intermedial part of APH; APHl, the lateral part of APH; APHcl, the caudolateral part of APH; S, the superficial layer; C, the cortical plate; PV, the periventricular layer. Dashed lines indicate the division between subregions and layers.

Fig. 3

Overview of classic cadherin mRNA expression in the APH of developing chicken embryos at E14 and E18. (A, B) Thionin staining for anatomical structures. (C, D) Cdh2. (E, F) Cdh4. (G, H) Cdh6B. (I, J) Cdh7. (K, L) Cdh8. (M, N) Cdh9. (O, P) Cdh11. (Q, R) Cdh12. (S, T) Cdh18. (U, V) Cdh19. (W, X) Cdh20. APHm, the medial part of the APH; APHi, the intermedial part of the APH; APHl, the lateral part of the APH; APHcl, the caudolateral part of the APH. Dashed lines indicate the division between subregions. The asterisks indicate artefacts. Scale bar=1 mm.

Fig. 4

Overview of protocadherin cadherin mRNA expression in the APH of developing chicken embryos at E14 and E18. (A, B) Thionin staining for anatomical structures. (C, D) Pcdh1. (E, F) Pcdh7. (G, H) Pcdh8. (I, J) Pcdh9. (K, L) Pcdh10. (M, N) Pcdh15. (O, P) Pcdh17. (Q, R) Pcdh18. (S, T) Pcdh19. (U, V) Pcdh21. APHm, the medial part of the APH; APHi, the intermedial part of the APH; APHl, the lateral part of the APH; APHcl, the caudolateral part of the APH. Dashed lines indicate the division between subregions. The asterisks indicate artefacts. Scale bar=1 mm.

Fig. 5

Expression of cadherin mRNA in the APHm of developing chicken embryos at E14 and E18. (A, B) Cdh2. (C, D) Cdh4. (E, F) Cdh6B. (G, H) Cdh7. (I, J) Cdh8. (K, L) Cdh11. (M, N) Pcdh1. (O, P) Pcdh7. (Q, R) Pcdh8. (S, T) Pcdh9. (U, V) Pcdh10. (W, X) Pcdh17. (Y, Z) Pcdh19. S, the superficial layer; C, the cortical plate; PV, the periventricular layer. Dashed lines indicate the division between subregions and layers. The asterisks indicate artefacts. Scale bar=250 μm.

Fig. 6

Expression of cadherin mRNA in the APHi of developing chicken embryos at E14 and E18. (A, B) Cdh2. (C, D) Cdh4. (E, F) Cdh6B. (G, H) Cdh7. (I, J) Cdh8. (K, L) Cdh11. (M, N) Pcdh1. (O, P) Pcdh7. (Q, R) Pcdh8. (S, T) Pcdh9. (U, V) Pcdh10. (W, X) Pcdh17. (Y, Z) Pcdh19. S, the superficial layer; C, the cortical plate; PV, the periventricular layer. Dashed lines indicate the division between subregions and layers. The asterisks indicate artefacts. Scale bar=250 μm.

Fig. 7

Expression of cadherin mRNA expression in the APHl of developing chicken embryos at E14 and E18. (A, B) Cdh2. (C, D) Cdh4. (E, F) Cdh6B. (G, H) Cdh7. (I, J) Cdh8. (K, L) Cdh11. (M, N) Pcdh1. (O, P) Pcdh7. (Q, R) Pcdh8. (S, T) Pcdh9. (U, V) Pcdh10. (W, X) Pcdh17. (Y, Z) Pcdh19. S, the superficial layer; C, the cortical plate; PV, the periventricular layer. Arrowheads indicate the cell clusters. Dashed lines indicate the division between subregions and layers. Scale bar=250 μm.

Fig. 8

Expression of cadherin mRNA expression in the APHcl of developing chicken embryos at E14 and E18. (A, B) Cdh2. (C, D) Cdh4. (E, F) Cdh6B. (G, H) Cdh7. (I, J) Cdh8. (K, L) Cdh11. (M, N) Pcdh1. (O, P) Pcdh7. (Q, R) Pcdh8. (S, T) Pcdh9. (U, V) Pcdh10. (W, X) Pcdh17. (Y, Z) Pcdh19. S, the superficial layer; C, the cortical plate; PV, the periventricular layer. Arrowheads indicate the scattered cells. Dashed lines indicate the division between subregions and layers. The asterisks indicate artefacts. Scale bar=250 μm.

Fig. 9

Expression of cadherin mRNA expression in the hippocampus of adult wild-type mice. (A) Thionin staining for anatomical structure. (B~N) Classic cadherin and protocadherin molecules. CA1–CA3, CA fields of hippocampus. DG, dentate gyrus. (B, F, J, L). Red dashed line, CA1; Black dashed line, DG. Scale bar=500 μm.