title: Effect of laser irradiation on the growth and development of fetal mouse limbs in an in vitro model.
abstract: OBJECTIVE
  The purpose of the present study was to examine the effects of laser irradiation on the growth and development of fetal limb tissue.
  
  
  METHODS
  Day 14 fetal mouse limbs (n=168) were irradiated with gallium arsenide laser (904 nm, spot size=0.002 cm2, pulse duration=200 nanoseconds, peak power=30 mW) for 1 minute each day while being maintained in an organ culture system for 3 or 5 days at the following energy densities [O (control), 0.23, 1.37, 2.75, 3.66, and 4.58 J/cm2].
  
  
  RESULTS
  Computer image analysis of photographic images showed that there was a significant inhibition (P < 0.05) of new tissue growth after administration of lower energy densities of laser (0.23 and 1.37 J/cm2). These low-energy densities of laser irradiation also produced increased dermal cell number and collagen fiber thickness as assessed with qualitative histologic analysis of limb development by a blinded observer. Quantitative analysis of collagen distribution by color densitometric analysis of tissue sections stained with sirus red and fast green confirmed that there was a significantly greater (P < 0.05) amount of collagen present in the dermis of limbs treated with low-energy densities of laser (0.23 and 1.37 J/cm2).
  
  
  CONCLUSIONS
  Laser irradiation directly affected the growth and development of day 14 fetal mouse limbs in an organ culture system.
mesh_terms: D000818:Animals; D003094:Collagen / Q000032:analysis; D005314:Embryonic and Fetal Development / Q000528:radiation effects*; D004817:Epidermis / Q000473:pathology; D005121:Extremities / Q000196:embryology* / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D007834:Lasers / Q000009:adverse effects*; D051379:Mice; D008815:Mice, Inbred Strains; D009924:Organ Culture Techniques / Q000379:methods; D011247:Pregnancy; D015203:Reproducibility of Results