File:Bailey470.jpg

Fig. 470. Vertical section through retina of a five and one-half months' human embryo

Modified from Lange.

The bipolar cells (Fig. 468, e), which with their processes constitute the middle or second optic neurone, also develop from cells of the nuclear layer and are probably bipolar at the time that the rod and cone cells are in the unipolar condition. Reference to the two bipolar cells shown in Fig. 468, e, ey shows that at this stage in their development their outwardly directed processes extend to the outer limiting membrane. These processes must either actually shorten or else fail to grow in length proportionately as the retina increases in thickness, for in the mature retina they end in relation with the centrally (inwardly) directed processes (axones) of the rod and cone cells. According as they are in relation with rod cells or cone cells, they are known as rod bipolars or cone bipolars. The retinal layer in which the axones of the rod and cone cells and the dendrites of the rod and cone bipolars intermingle is the outer, molecular layer of the adult retina. It is first distinctly recognizable as a molecular layer about the end of the fifth month (Fig. 470).

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Reference

Bailey FR. and Miller AM. Text-Book of Embryology (1921) New York: William Wood and Co.

Cite this page: Hill, M.A. (2024, April 27) Embryology Bailey470.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey470.jpg

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