Development Of Stratum Griseum Et Fibrosum Superficiale In Chick Tectum And Their Neuron Morphology

Avian optic tectum receive approximate90%projection from retinal ganglion cells,being an very important relay in the vision formation. It has an obvious delaminatedstructure alternating with grey and white matter. Stratum griseum et fibrosum superficiale(SGFS) is its thickest layer, being composed of10sub-layers of a-j. They receive thevisual information from the nerve terminals of optic nerves and send them to the cells indeeper layers and other relative regions within visual pathway after processing. In thisstudy, neuron morphology in SGFS (sub-layer C, D, E, F, G, H) of3day old chick andthe development of SGFS in different embryo days were observed using the Golgi-Coxand Nissl staining methods to apply some data for neurobiology. The observation itemsinclude the soma shape and size, dendrite field of the neurons within tectum SGFS in3day old chick, thickness of SGFS and its percent on whole tectum, thickness ofsub-layers and their percent on SGFS, thickness of different region of SGFS andsub-layers in E11, E14, E17, and E20. The results showed that more complete neuronsoma and dendrites can be seen in sub-layers of SGFS after stained with Golgi-Coxmethod in the section of chicken tectum. Most of their soma looked oval, irregularpolyangular, spindle, and triangular. According to the the size of soma, neurons in eachsub-layer were divided into giant cells, large cells, middle cells and small cells. TheGiant cells are most in sub-layer C, D, F and H. The middle and small cells are most insub-layer E. Whereas in sub-layer G, the small ones is more the other type cells. Two tosix primary dendrites were sent from soma, then sending secondary and tertiarysuccessively. The denrite fields are different among the sub-layers, being the order ofsub-layer F (77.91±21.54μm, mean±SD, n=579), E (103.72±32.86μm, n=348), C(116.75±40.38μm, n=455), H (119.23±41.52μm, n=540), G (131.45±51.63μm,n=809), D (157.98±62.95μm, n=765) from small to large. In the sections stained withNissl, obvious delaminated structure in sub-layers can be observed. Through measureand analysis, the average thickness of SGFS in E11was (322.50±31.01) μm, occupying59.34％(n=67) on whole tectum. That in E14was (334.01±29.42)μm, occupying45.35％(n=82) on whole tectum. In E17it was (366.48±31.01)μm, occupying49.73％(n=64)on whole tectum. In E20it was (394.15±40.59)μm, occupying57.62％(n=55) on wholetectum. The measure and analysis on different region in sub-layers of SGFS indicatedthat the lateral patr is generally thicker than the dorsal and ventral ones. The growing speed in ventral part is the faster in E14-E17, being thicker than lateral and dorsal ones.In the embryonic stage the average thickness order of sub-layers of SGFS is sub-layer H,D, C, F, G, and E from large to small.