title: Leg Regrowth in Blaberus discoidalis (Discoid Cockroach) following Limb Autotomy versus Limb Severance and Relevance to Neurophysiology Experiments.
abstract: BACKGROUND
  Many insects can regenerate limbs, but less is known about the regrowth process with regard to limb injury type. As part of our neurophysiology education experiments involving the removal of a cockroach leg, 1) the ability of Blaberus discoidalis cockroaches to regenerate a metathoracic leg was examined following autotomy at the femur/trochanter joint versus severance via a transverse coxa-cut, and 2) the neurophysiology of the detached legs with regard to leg removal type was studied by measuring spike firing rate and microstimulation movement thresholds.
  First appearance of leg regrowth was after 5 weeks in the autotomy group and 12 weeks in the coxa-cut group. Moreover, regenerated legs in the autotomy group were 72% of full size on first appearance, significantly larger (p<0.05) than coxa-cut legs (29% of full size at first appearance). Regenerated legs in both groups grew in size with each subsequent molt; the autotomy-removed legs grew to full size within 18 weeks, whereas coxa-cut legs took longer than 28 weeks to regrow. Removal of the metathoracic leg in both conditions did not have an effect on mortality compared to matched controls with unmolested legs.
  Autotomy-removed legs had lower spontaneous firing rates, similar marked increased firing rates upon tactile manipulation of tibial barbs, and a 10% higher electrical microstimulation threshold for movement.
  
  
  CONCLUSIONS
  It is recommended that neurophysiology experiments on cockroach legs remove the limb at autotomy joints instead of coxa cuts, as the leg regenerates significantly faster when autotomized and does not detract from the neurophysiology educational content.
authors.affiliation: Research and Development, Backyard Brains, Inc., Ann Arbor, Michigan, United States of America.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Marzullo
mesh_terms: D000818:Animals; D003058:Cockroaches / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009482:Neurophysiology; D012038:Regeneration / Q000502:physiology*
references.citation: J Neurosci Methods. 2005 Feb 15;141(2):171-98
references.pmid: 15661300
references.citation: PLoS Biol. 2015 Mar 20;13(3):e1002086
references.pmid: 25794301
references.citation: J Exp Biol. 1965 Apr;42:191-203
references.pmid: 14323763
references.citation: J Undergrad Neurosci Educ. 2007 Spring;5(2):A28-34
references.pmid: 23494074
references.citation: J Embryol Exp Morphol. 1985 Feb;85:177-90
references.pmid: 3989448
references.citation: Aust J Biol Sci. 1953 Aug;6(3):485-500
references.pmid: 13093536
references.citation: PLoS One. 2012;7(3):e30837
references.pmid: 22470415
references.citation: Science. 1970 Jan 2;167(3914):61-2
references.pmid: 5409478
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 Feb;188(1):55-69
references.pmid: 11935230
references.citation: J Undergrad Neurosci Educ. 2013 Oct 15;12(1):A66-74
references.pmid: 24319394
references.citation: Am J Physiol. 1992 Jun;262(6 Pt 3):S18-22
references.pmid: 1616063
references.citation: J Exp Biol. 2009 May;212(Pt 10):1463-76
references.pmid: 19411540
references.citation: J Embryol Exp Morphol. 1983 Jun;75:151-64
references.pmid: 6886608
references.citation: Biol Bull. 1977 Aug;153(1):145-62
references.pmid: 889943
references.citation: Wilhelm Roux Arch Entwickl Mech Org. 1963 Sep;154(5):434-465
references.pmid: 28354197
references.citation: J Exp Biol. 2010 Jun 1;213(11):1907-20
references.pmid: 20472778
references.citation: Brain Res. 1980 Oct 6;198(2):253-69
references.pmid: 7407598
references.citation: PLoS One. 2012;7(6):e38003
references.pmid: 22701594