Embryonic staging series for the African House Snake (Lamprophis fuliginosus) using external morphology

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Embryonic staging series for the African House
Snake (Lamprophis fuliginosus) using external
morphology

• Eric Dichter and Scott Boback. Department of
  Biology, Dickinson College, Carlisle, PA.

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Outline

• The motivation
• The question
• African House staging series
• Continuing work
• Goals for future

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Darwins finches morphological variation of
beaks
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Bone morphogenetic protein (Bmp4)
Abzhanov et al. 2004
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Bmp4
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Is Bmp4 responsible for head shape differences
between island and mainland boas?
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African House Snake staging series

• oviparous
• smaller size
• shorter time of development
• docile
• VERY prolific reproduction

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Staging criteria for Rock Python
Stage External morphological characteristics
1 Mandibular process does not extend to eye, no scales, 5-6 body coils
2 Mandibular process extending rostral to eye
3 Mandibular process extends midway between eye and maxilla, scales visible on body, 3-4 body coils
4 Mandibular process lines up with maxilla, 3 coils
5 Cervical flexure gt 90, heart protrudes from body cavity
6 Scales on head, heart internalized, 2-3 coils
7 Fusion of eyelids in center of eye, 2 coils
8 Cervical flexure 120, body wall closed, pigmentation beginning, 2 coils
9 Cervical flexure 180, brain not visible through skin, pigmentation patter clear but pale, 1-2 coils
10 Resembles neonate, 1-2 body coils, egg tooth visible
Adapted from Boughner et al. 2007
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Staging criteria for African House

• Mandibular length (relative to maxilla)
• Brain development
• Location of organs
• Angle of cervical flexure
• Weight
• Length
• Eye pigment
• Scales

Adapted from Boughner et al. 2007
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0-1 days
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6 days
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9 days
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13 days
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16 days
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13 days
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16 days
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27 days
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34 days
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43 days
External hemipenes
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54 days - hatched
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Conclusions

• Rate of development variable depends on
  environment, health of mother, genetics
• Comparable development at oviposition
• Development of L. fuliginosus similar to Python
  sebae much shorter incubation

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Continuing work

• Mating snakes, incubating eggs, harvesting more
  embryos
• Clearing and staining location, timing of bone
  development in jaws
• In situ hybridizations determine presence,
  location, timing of expression of certain growth
  factors (Bmp4, Bmp2, Fgf8, Shh)

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Many thanks to

• Prof. Boback
• Prof. Mistry
• Neil Ford
• Ali Maksimak
• Mike Montross
• Chase Walling

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Works cited

• Boughner, J.C., Buchtova, M., Fu, K., Diewert,
  V., Hallgrimsson, B., Richman, J.M. 2007.
  Embryonic development of Python sebae I
  Staging criteria and macroscopic skeletal
  morphogenesis of the head and limbs. Zoology
  212-230.
• Abzhanov, A., Protas, P., Grant, B. R., Grant,
  P.R., Tabin, C.J. 2004. Bmp4 and Morphological
  Variation of Beaks in Darwins Finches