THE OBSERVATION OF TRANSPLANTED EMBRYONIC MOTONEURONS IN THE DENERVATED MUSCLES OF ADULT RATS

Objective To observe the survival of embryonic motoneurons after they were transplanted into the denervated skeletal muscles and to find a n ew method to retard the atrophy of denervated muscles. Methods Dissoci ated embryonic motoneurons prelabled with 5-bromo-2' -deoxyuridine (Br dur) on the embryonic days 12 were injected into the denervated gastro cnemius muscles of adult rats. Then gastrocnemius muscles were process ed with Nissl staining, acetylcholinesterase staining and Brdur immuno cytochemical staining to show the implanted motoneurons at 9 and 22 we eks post-transplantation. Myofibrillar ATPase staining was used to sho w the morphology of muscle fibers. The rats in experimental group were implanted with embryonic motoneurons in the predenervation muscles, w hile the rats in control group were injected with just culture medium without motoneurons. Results Embryonic motoneurons survived, developed and extended long axons to form neuromuscular junctions with the dene rvated muscles. The differentiation of muscle fibers and fiber type gr ouping occurred among bigger fibers in experimental group. The transve rse area was smaller and there was no apparent fiber type grouping in control group. Conclusions Embryonic motoneurons can survive, develop and reinnervate denervated muscles after being transplanted into dener vated muscles. It is worth further investigating on ameliorating the a trophy of denervated muscle.