No abstract

No abstract

SII,VA SASSO2 Ceritro J e Micruscopi(1 EletrOnicn. Escolil PolitP~-nicn, C'niversidade d r Siiu t'aulo and Departurnento de Histolugin. Futuldnde de Odontolo+,+a, Unzvevsidnde de Suu PuuIu, SHo P d o , B r a d ABSTRACTThe "cuticle," which revests the starfish tube foot, has been studied by electron microscopy and thc findings correlated with histochemical observations. 'The "cuticlc" is composed by two distinct zoncs; an outer zone including numerous microvilli, which extend from lhe inner zone into and through a fibrillar substance distinctly organized in two layers. These microvilli protrude slightly beyond the outer surface, where thcir tips give rise to numerous extremely delicate fibrils. The second inner zone, of quite variablc thickness and condensation of material, presents a coarser fibrous matrix where organelles and inclusions can be found.The wholc cuticular complex docs nut dcrive from thc majority of the epithclial cells, but is probably an extension of a special kind of I'-shaped cells appcaring at inlervals, thc "cuticle" forming a syncytial surface.Ilistochemical investigations indicate that the "cuticlc" contains a combination of neulral and acid mucopolysaccharide, with a marked ncutrul predominance, the outcr one displaying also an extremely thin coat of acid mucopolysaccharide with thc sulfate group. The oi-dered an-angement of the microvilli suggcsts that this sitiialion is imposed by the strong bond existing between the microvilli and the ouble mucopolysaccharidc layers which would act as a cemcnting substance stabilizing the cntire apical surface of the cell.

No abstract

No abstract