Training Presentation Estrus Detection, Weaning and Sexing Mice

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Training Presentation Estrus Detection, Weaning
and Sexing Mice

• University of South Florida
• (July 2005)

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Estrus Detection

• Both of these mice are in estrus they are in
  different stages.
• The mouse on the top would be chosen for an
  immediate breeding pair set up.
• The mouse on the bottom is in an earlier stage of
  estrus.

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Estrus Detection

• Estrus Non-Estrus
• Note the swollen, moist Note the
  closed vaginal
• and open appearance to the
  opening and pale mucus
• vaginal opening coloration
  membrane color.
• of mucus membranes is pale.

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Estrus Detection

• Again, note the swollen moist appearance of
  the tissues surrounding the vaginal opening,
  bright pink to purple in coloration.

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Estrus Detection

• Different Stages
• Subtle differences
• are evident between
• these mice.
• Both mice would be
• suitable for pairing
• with a male if one
• were setting up pseudo-pregnancies. However, the
• mouse on the R has a higher probability of
  plugging.

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Estrus vs. Non-Estrus

• swollen vaginal tissue no swelling evident
• gaping vaginal opening closed vaginal
  opening
• moist tissues dry tissues
• bright pink/purple pale mucus membranes
• mucus membranes

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Copulatory Plugs In Mice

• The copulatory plug (most often referred to as
  the vaginal plug), is made of several different
  components---sperm, ejaculate fluids, and mucus
  are primary substances that harden within the
  cervix.
• The plug forms following copulation and is
  visible within, or slightly protruding from, the
  vaginal opening. Its presence indicates a
  successful mating but does not guarantee that
  conception has occurred.

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Checking for Plugs

• Checking females
• for plugs is best
• done in the early
• morning (before
• 900 a.m.) if the
• animals are housed
• under a typical
• 12/12 light cycle.

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Checking for Plugs

• The plug is opaque,
• whitish, and has a waxy consistency.
  It is generally easy to identify
  while still
• within the vaginal opening.
• It may also be identified in the bedding as a
  large waxy
• chunk, if one checks closely. Generally, plugs
  are expelled
• close to the nest/sleep area.

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Checking for Plugs

• Sometimes
• the plug is
• difficult to
• visualize in
• situ. To aid with
• its identification,
• one can gently
• palpate the area to help distend and partially
  expel the plug.
• The use of forceps is not recommended. Extreme
  care must be
• taken if forceps are used, and the plug should
  never be
• removed.

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Rodent Pup Sexing

• Sexing young rodents can be challenging but
  with practice, pups as young as day 3 can be
  consistently identified.
• Males have twice the anogenital distance that
  females have.
• The nipple line in females is identifiable as
  early as day 8 or 9.
• Once hair is present D9, the area between the
  testicles and anus is completely grown over with
  hair in females the area is defined as a
  hairless line between the vaginal opening and
  anus.

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Day 5

• Male Female

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Day 7

• Female Male

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Day 12

• Male-right
• note the hair
• growth between
• the anus and
• prepuce
• Female-left
• note the visible
• line between the
• vaginal opening
• and the anus, note the nipple line.

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Day 21

• Female-left Male-right

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Adult

• Female Male
• Note line between anogenital area Note
  anogenital area
• is clearly visible nipples are easily
  is completely fur covered.
• identified.