Splenic regeneration does not occur after sub-total splenectomy

The case of a 6-year-old male undergoing sub-total splenectomy after a trivial fall is described. Although the remaining spleen survived, no increase in splenic bulk had occurred 8 years later as measured by isotope scan.     

Optical coherence tomography for observation of the olfactory epithelium in mice

Objective

Optical coherence tomography (OCT) is an imaging tool that exploits the coherence of infrared light and is clinically utilized in the field of ophthalmology and dermatology. This study aimed to examine the feasibility of using OCT for diagnosing degeneration and regeneration of the olfactory epithelium in mice.

Recovery of olfactory behavior. I. Recovery after a complete olfactory bulb lesion correlates with patterns of olfactory nerve penetration

The olfactory system is an excellent system in which to study issues related to potential functional recovery after a debilitating brain injury. The olfactory system is well-characterized, easily accessible and there are a vast number of studies available from a variety of perspectives. The experimental aim of this research is to examine the anatomical correlates associated with potential behavioral recovery in rats that receive complete olfactory bulb lesions as neonates or as adults. The results show that behavioral recovery occurs only when olfactory nerve penetration of the central nervous system is observed. Further, both olfactory nerve penetration and behavioral recovery are age-dependent phenomena. The olfactory nerve penetration only occurs when the olfactory bulb lesion is performed in neonates. Behavioral recovery of olfactory ability follows a linear trend and reaches near normal levels during the six week behavioral testing period. Histological analysis using an antibody for olfactory marker protein (an olfactory nerve-specific marker) reveals two potential candidates for the anatomical pathway responsible for behavioral recovery: olfactory nerve to orbital frontal cortex and olfactory nerve to olfactory peduncle. This report presents evidence that recovery of olfactory ability can occur in the absence of the olfactory bulb if the lesion is performed when the rat is still a neonate.     

Weak electric current accelerates motoneuron regeneration in the sciatic nerve of ten-month-old rats

When a weak direct current (DC) of 10 μA driven by an implantable device was applied to a crushed sciatic nerve in 9–10-month-old rats, regeneration was accelerated as assessed electrophysiologically. Rats underwent a sciatic nerve crush of the right leg and were randomly assigned to one of three groups: (i) Cathode Distal (CD); (ii) Sham Implant (SI); or (iii) No Implant (NI). On post-operative days 25–39 each rat r received a measurement of evoked electromyograms (EMG) in the foot. In addition each rat received a behavioural test score (BTS). This BTS correlated well with the evoked EMG results showing the behavioural relevance of the EMG results. NI rats performed the same as SI in the evoked EMG procedure, but CD rats performed significantly better than both the control groups. The recovery period in the CD rats was 21% shorter than in either the sham-treated or untreated controls showing that weak DC can greatly enhance nerve regeneration in adult rats. This result was in contrast to previous work in younger rats where DC treatments had no effects. The discrepancy is discussed in relation to the slowing of regeneration in older rats.     

The fine structure of de-and reinnervated muscle spindles

Summary Sensory and motor nerve endings in lower lumbrical muscles of rats were surprisingly well reconstituted following a single crush lesion of the sciatic nerve. No motor nerve endings were noted in the equatorial region, nor sensory endings in the polar regions of the muscle spindles examined.1 and 2 months after the lesion, multiple axonal sprouts reinnervated an increased number of intrafusal Schwann cells and, occasionally, of intrafusal muscle fibers. This frequently resulted in abnormal contact relationships between multiple Schwann cell processes and muscle fibers, nerve terminals and muscle fibers, and nerve terminals and Schwann cell processes. In addition, the remaining or newly formed basement membranes of the respective Schwann cells, axons, or muscle fibers were often irregularly arranged. Freely floating basement membranes adjacent to intrafusal muscle fibers of Schwann cells were more frequently observed than in normal spindles. The internal structure of regenerated nerve terminals varied considerably; however, there was a wide range of variability in the structure of normal nerve terminals too.Most endings, at 14 and 24 months after the lesion, had a normal appearance although some altered relations between nerve terminals and muscle, fibers were still present. Some proliferated Schwann cells or Schwann cell processes as well as basement membranes were not reinnervated. These could represent the only evidence of the preceding lesion.Presented in part at the 3rd Symposium on Neuromuscular Disorders, September 12–14, 1973 in Janské Láznê, SSR.     

Survival, regeneration and functional recovery of motoneurons after delayed reimplantation of avulsed spinal root in adult rat

We have established that extensive reinnervation and functional recovery follow immediate reimplantation of avulsed ventral roots in adult rats. In the present study, we examined the consequences of reimplantation delayed for 2 weeks after avulsion of the C6 spinal root. Twelve and 20 weeks after delayed reimplantation, 57% and 53% of the motoneurons in the injured spinal segment survived. More than 80% of surviving motoneurons regenerated axons into the reimplanted spinal root. Cholinesterase-silver staining revealed axon terminals on endplates in the denervated muscles. The biceps muscles in reimplanted animals had atrophied less than those in animals with avulsion only, as indicated by muscle wet weight and histological appearance. After electrical stimulation of the motor cortex or the C6 spinal root, typical EMG signals were recorded in biceps of reimplanted animals. The latency of the muscle potential at 20 weeks was similar to that of sham-operated controls. Behavioral recovery was demonstrated by a grooming test and ipsilateral forepaw movements were well coordinated in both voluntary and automatic activities. These results demonstrate that ventral root reimplantation can protect severed motoneurons, enable the severed motoneurons to regenerate axons, and enhance the recovery of forelimb function even when it is delayed for 2 weeks after avulsion.     

Development of cultivated mucosal epithelial sheet transplantation for ocular surface reconstruction

Regenerative medicine via tissue engineering is a newly developed medical field based on the use of somatic stem cells to generate biological substitutes and improve tissue functions. The achievement of these objectives depends on two important factors: stem cells, which are high in proliferability and differentiability, and the substrates that support them. In order to reconstruct the ocular surface in patients with severe ocular surface diseases, we decided to investigate the feasibility of human amniotic membrane as an epithelial carrier, and found that denuded amniotic membrane was the most appropriate substrate for this purpose. To develop the surgical treatment using denuded amniotic membrane as a carrier, we established the tissue engineering system for making transplantable epithelial sheets of either corneal or oral mucosal epithelial cells for ocular surface reconstruction.