Page 245 - Biology_F5
P. 245

Biology for Advanced Level Secondary Schools

           tapetum which is found behind the retina.  the vision of cats and nocturnals in dim
           This protein layer reflects light back into  light. The bright light shown by cats’ eyes
           the eye and gives an opportunity for rod  at night is the result of the reflection from
           cells to absorb it. This character improves  the tapetum.



                                                                          Choroid epithelium
          FOR ONLINE READING ONLY
                       Rod                                                   Layer of pigment
                   Vesicles
                     Cone                                           Outer
                                                                    segment
             Infolding of cell
             surface membrane


                                                                  Constriction
                                                                                  Photoreceptor layer
                 Pair of cilia
              Mitochondria

                                                                     Inner
                                                                     segment


                     Nucleus
              End bulb
              (equivalent of
              synaptic knob)
                                                                     Synaptic
                                                                     region

                   Horizontal cell

                 Bipolar neurone
                                                                                  Intermediate layer
                      Amacrine cell








               Ganglion cell
                                                                      Internal
                                                                      surface layer



                                                                                 Axon of optic
                                                                                 nerve

                                          LIGHT RAYS

                                       Figure 4.29: Structure of the retina

                                                                      Form Five Student’s Book
            238
   240   241   242   243   244   245   246   247   248   249   250