Ultrastructure of the myotendinous junction of the medial pterygoid muscle of adult and aged Wistar rats.
The myotendon junction (MTJ) is a specialised area into the muscle fibers where the sarcoplasmic membranes connect to the collagen fibers bundles. There are few data about plasticity of the MTJ in aging processes. The aim of this study is to analyse the ultrastructure characteristics of MTJ of medial pterygoid muscle of adult and aged rats. Employing the transmission electron microscopy method, twenty male rats Wistar (Rattus norvegicus) were divided into two groups: A (n=10) with 12 months of age; B (n=10) 24 months of age. The animals were anaesthetised with overdose the urethane (3g/kg, i.p.) and sacrified during the perfusion with modified Karnovsky solution. The specimens were post-fixed in a 1% osmium tetroxide solution, dehydrated in ascending concentration of ethanol and embedded in Spurr resin. The thin sections, of 90 nm thick, were counterstained with uranyl acetate and lead citrate solution, and examined in a Jeol 1010 transmission electron microscope. The fine structure of the MTJ of group A revealed the defined interdigitations and disposed in several levels of deep formations containing the collagen fibers. In the group B, such structures did not observed, detecting the projections irregular in shape, and large of extra matrix with in aspect of remodelling. In conclusion it was possible to identify the plasticity of MTJ in the group B which presented several morphological alterations comparing to the adult animals. These data of group B suggested the occurrence of aging processes in the MTJ in rats.
Ciena
Adriano Polican
AP
Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
Luques
Isabela Ugo
IU
Dias
Fernando José
FJ
Yokomizo de Almeida
Sonia Regina
SR
Iyomasa
Mamie Mizusaki
MM
Watanabe
Ii-Sei
IS
D000367:Age Factors; D000818:Animals; D008297:Male; D046529:Microscopy, Electron, Transmission; D011626:Pterygoid Muscles / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013710:Tendons / Q000648:ultrastructure*