ABSTRACT
A scaffold fabricated with lysine/nerve growth factor (NGF)/poly (lactic acid coglycolic acid) copolymer (PLGA) and acellular pigskin was evaluated in vitro as a potential artificial nerve scaffold. Properties of the scaffold such as microstructure, mechanical property, degradation behavior in PBS and water, Schwann cell adhesion property, and release of NGF were investigated. Results showed PLGA had permeated into the porous structure of acellular pigskin; its breaking strength was 8.308 MPa, breaking extensibility was 38.98%, elastic modulus was 97.27 MPa. The porosities of the scaffold ranged from 68.3% to 81.2% with densities from 0.62 g/cm3 to 0.68 g/cm3. At 4 weeks of degradation in vitro, maximum mass loss ratio was 43.3%. The release of NGF could still be detected on the 30th day, and its accumulative release rate was 38%. Lysine added into the scaffold neutralized the acidoid preventing degradation of PLGA to maintain a solution pH value. Schwann cells had grown across the scaffold after co-cultivation for 15 days. These in vitro properties of the pigskin based composite might indicate its potentiality to be an artificial nerve scaffold.
Subject(s)
Animals , Acellular Dermis , Biocompatible Materials , Guided Tissue Regeneration , Lactic Acid , Pharmacology , Lysine , Pharmacology , Nerve Growth Factors , Chemistry , Pharmacology , Nerve Regeneration , Polyglycolic Acid , Pharmacology , Swine , Tissue Engineering , Tissue ScaffoldsABSTRACT
Objective To explore the relationship of the changes of memory behavior and the of changes of the parameter of synapse structure in the brain cortex and hippocampus of chronic cerebral hypoperfusion rats Methods Chronic cerebral hypoperfusion rat model was established by ligating bilateral common carotid arteries of the old rats (over 12 months) The rats were divided into 3 groups, normal, 2 months ischemia, and 4 months ischemia groups The memory behavior changes were observed with a computerized shuttle training case The ultrastucture of synapse were observed with electron microscopy for the number density, length of activity cord, area of synapses disk, surface density of the synapse, and the results were analyzed with stereology and image analyses The relationship between the behavior and the ultrastructure were studied Results Active avoidance response (AAR) and passive avoidance response (PAR) were decreased in the 2 months ischemia group and the 4 months ischemia group The number density (Nv) of the synapses in the brain cortex and hippocampus were reduced in the 2 months ischemia group and the 4 months ischemia group The length of activity cord (L), the area of synapses disk (S), the area density (Sv) in the hippocampus decreased in the 2 and 4 months ischemia group, and those in the brain cortex did not change in the 2 groups Conclusion The decrease of the number density (Nv) and the length of activity cord (L) of synapses in the chronic cerebral hypoperfusion is related to the memory behavior changes
ABSTRACT
The renomedullary interstitial cells (RMIC) of rat were investigated using the method of HCl-Tween removing extracellular material and scanning electron microscope. According to the shape and distribution, the RMIC may be divided into 3 groups. However, most of RMIC belong to the first group.The cell of the first group is fibroblast-like, which has an irregular cylindrical body (about 2-6 ?m in short diameter and 5-12 ?m in long diameter) and several processes from both ends of the body. The processes from one end are distributed on the wall of the renal tubule (Henle's loop or collecting tubule); and those from the other end on the blood vessel, sometimes, with the vascular pedicles formed by the expanding of the process end. The long axis of the cells of the first group is perpendicular to the tubules and blood vessels, so the cells are bridged between them.The second group cell has a round body without process and is located at the body of the first group cell.The third group cell is star-like, which has a large body (about 5-8 ?m in diameter) and a few small processes. They are randomly distributed, and sometimes, arranged as a line along the blood vessel.
ABSTRACT
By using replica cast SEM method, the vascular architecture of the dental pulp of rat incisors was studied. The characteristics of the vascular architecture are as follows:1. The axis of the dental pulp is occupied by the central vascular bundle, which consists of 10 to 20 arterioles and 8 to 12 venules.2. The arterioles (30-50?m in diameter) and the venules (50-80?m in diameter) located in the central bundles are arranged parallely in a relatively long distance as a countercurrent system. The longest distance is about 12 mm.3. Each arteriole of the central vascular bundle supplies an independent area of the dentin of the tooth. The territory of an arteriole is about 700 to 1400 ?m in length.4. The arteriole of the central bundle breaks up into capillaries (4～6?m in diameter) which are mainly distributed over the odontblast area and form a complex 3-dimensional plexus.
ABSTRACT
The microvascutature of the adrenal medulla in the rats and mice were studied by scanning electron microscopy of vascular replicas.There are portal venules between the adrenal cortex and medulla,which are the side branches of the collecting venules of the adrenal cortex and break into capillaries at the adrenal medulla.The adrenal medulla in mice is mainly supplied by these portal venules,and in a rat adrenal medulla,there are also 5—8 medullar arterioles besides the portal venules.Ring-like constrictions appear to be the characters of sphincter at the ending parts of the portal venules,the branches of the medullar arterioles,the collecting venules,and the medullar venules which drain the medullar capillaries as well.The authors believe that the adrenal cortex controls the medulla by the way of the portal venules.