Measurement of adhesive forces between the sensory retina and the pigment epithelium.

The strength of the adhesion between the retina and the pigment epithelial cell layer was measured using rectangular strips of tissue prepared from freshly enueleated cats' eyes. The weights required to peel away the retina over the tapetum lucidum region in 3 mm width strips ranged from 40 to 55 mg and in the pigmented region, from 75 to 150 mg. Proportionately higher weights were observed with wider strips of tissue. The energy required to separate the two layers, using tissue strips of 3 mm width, was calculated from recordings made on a tensiometer. These values were found to be 8·2 ± 1·3 ergs/cm2 in the tapetum lucidum region and 18·8 ± 1·8 ergs/cm2 in the pigmented region. For wider strips, the mean energy of the adhesion per unit area was slightly higher. The attachment between the sensory retina and the underlying tissue in the ora serrata was found to be very strong; continued pulling resulted in stretching and ultimate tearing of the tissue without achieving an actual separation. The source of the adhesive forces in the pigmented and tapetum lucidum regions is discussed in terms of (a) anatomical relationships between the apical process of the pigment epithelial cells and the outer segments and (b) the possible role of the acid mucopolysaccharides of the interstitial matrix.