Fig. 5. Attachment of muscle to mesoglea in Pelmatohydra; o is a light 

 micrograph of a longitudinal section of a tentacle. The epidermis is at the 

 left and its scalloped surface indicates partial contraction of the tentacle. 

 The dense line at the base of the epidermis (arrow) indicates a specialized 

 form of attachment of muscle to mesoglea. A similar region viewed in cross 

 section with the electron microscope is shown at b. Epidermal muscle fibers 

 lie adjacent to the mesoglea. An extension of one muscle fiber becomes as- 

 sociated with a projection of mesoglea. See text. L, lumen; N, nucleus; M, 

 muscle; ME, mesoglea. o— 2,000X. 6— 20,500X. 



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