Theiler Staging Criteria for Mouse Embryo Development

For full descriptions of Theiler staging and mouse anatomy visit http://genex.hgu.mrc.ac.uk/Atlas/intro.html

TS 1

(0-2.5)

TS 2

(1-2.5)

TS 3

(1-3.5)

TS 4

(2-4)

TS 5

(3-5.5)

TS 6

(4-5.5)

TS 7

(4.5-6)

TS 8

(5-6.5)

TS 9

a

(6.25-7.25)

b

One-cell egg Dividing egg 2-4 cells Morula 4-16 cells

Blastocyst, inner cell mass apparent

16-40 cells

Figures represent development of F1 hybrid (C57BL X CBA) mice. Descriptions of embryos at TS9 – 11 based on Downs & Davies, 1993, and apply to outbred mice of the PO strain. Numbers in parentheses under Theiler stages represent approximate dpc range. Relative sizes of illustrations not to scale. The cartoons are intended as a illustrative guide only.

Blastocyst

(zona-free)

Attachment of

blastocyst, primary endoderm covers blastocoelic surface of inner cell mass

Implantation and formation

of egg cylinder. Ectoplacental cone appears, enlarged epiblast, primary endoderm lines mural trophectoderm

Differentiation

of egg cylinder. Implantation sites 2x3mm.

Ectoplacental cone region invaded by maternal blood, Reichertís membrane and proamniotic cavity form

First sign of radial asymmetry. a Pre-streak

(PS), advanced endometrial reaction, ectoplacental cone invaded by blood, extraembryonic ectoderm, embryonic axis visible.

b Early streak

(ES), gastrulation starts, first evidence of mesoderm.

Theiler Stage

dpc

1 1 2 1 3 2 4 3 5 4 6 4.5

7 5 8 6 9 6.5

10 7 11 7.5

12 8 13 8.5

14 9 15 9.5

16 10 17 10.5

18 11 19 11.5

20 12 21 13 22 14 23 15 24 16 25 17 26 18 27 19

Theiler Staging Criteria for Mouse Embryo Development

For full descriptions of Theiler staging and mouse anatomy visit http://genex.hgu.mrc.ac.uk/Atlas/intro.html

a

TS 10

(6.5-7.75)

a

TS 11

(7.25-8)

TS 12

(7.5-8.75)

TS 13

(8-9.25)

TS 14

(8.5-9.75)

TS 15

(9-10.25)

TS 16

(9.5-10.75)

TS 17

(10-11.25)

TS 18

(10.5-11.25)

b b c c

Turning of the

embryo, 1st branchial arch has maxillary and mandibular components, 2nd arch present

8-12 somites.

Absent 3rd branchial arch

Formation & closure of ant.

neuropore, otic pit indented but not closed, 3rd branchial arch visible

13-20 somites.

Absent forelimb bud a Neural plate (NP), head process developing, amnion complete

b Late neural plate

(LNP), elongated allantoic bud

c Early head fold (EHF)

d Late head fold (LHF), foregut invagination

First appearance of somites.

1-4 somites, allantois extends, 1st branchial arch, heart starts to form, foregut pocket visible, preotic sulcus (at 2-3 somite stage).

5-7 somites, allantois contacts chorion at the end of TS12 Absent 2nd arch, >7 somites

Formation of post.

neuropore, forelimb bud, forebrain vesicle subdivides

21-29 somites.

Absent hindlimb bud, Rathke's pouch

Posterior neuropore

closes, Formation of hindlimb & tail buds, lens plate, Rathke's pouch; the indented nasal processes start to form

30-34 somites.

Absent thin & long tail

Deep lens

indentation, adv. devel. of brain tube, tail elongates and thins, umbilical hernia starts to form

35-39 somites.

Absent nasal pits a Mid streak (MS), amniotic fold starts to form.

b Late streak, no

bud (LSOB), exocoelom.

c Late streak, early

bud (LSEB), allantoic bud first appears, node, amnion closing

d

Theiler Stage

dpc

1 1 2 1 3 2 4 3 5 4 6 4.5

7 5 8 6 9 6.5

10 7 11 7.5

12 8 13 8.5

14 9 15 9.5

16 10 17 10.5

18 11 19 11.5

20 12 21 13 22 14 23 15 24 16 25 17 26 18 27 19

Closure of lens

vesicle, nasal pits, cervical somites no longer visible

40-44 somites.

Absent auditory hillocks, anterior footplate

Theiler Staging Criteria for Mouse Embryo Development

For full descriptions of Theiler staging and mouse anatomy visit http://genex.hgu.mrc.ac.uk/Atlas/intro.html

TS 19

(11-12.25)

TS 20

(11.5-13)

TS 21

(12.5-14)

TS 22

(13.5-15)

TS 23 TS 24 TS 25 TS 26 TS 27

Lens vesicle completely separated from the surface

epithelium. Anterior, but no posterior, footplate. Auditory hillocks first visible

45-47 somites.

Absent retinal pigmentation and sign of fingers

Earliest sign of fingers (splayed-

out), posterior footplate apparent, retina pigmentation apparent, tongue well defined, brain vesicles clear

48-51 somites.

Absent 5 rows of whiskers, indented anterior footplate

Anterior footplate

indented, elbow and wrist identifiable, 5 rows of whiskers, umbilical hernia now clearly apparent

52-55 somites.

Absent hair follicles, fingers separate distally

Fingers separate

distally, only indentations between digits of the posterior footplate, long bones of limbs present, hair follicles in pectoral, pelvic and trunk region

56-~60 somites.

Absent open eyelids, hair follicles in cephalic region

Fingers & toes

separate, hair follicles also in cephalic region but not at periphery of vibrissae, eyelids open. Absent nail primordia, fingers 2 5 parallel

Repositioning of

umbilical hernia, eyelids closing, fingers 2-5 are parallel, nail primordia visible on toes.

Absent wrinkled skin, fingers & toes joined together Skin is wrinkled, eyelids are closed,umbilical hernia is gone. Absent ear extending over auditory meatus, long whiskers Long whiskers, eyes barely visible through closed eyelids, ear covers auditory meatus

Newborn mouse Theiler Stage

dpc

1 1 2 1 3 2 4 3 5 4 6 4.5

7 5 8 6 9 6.5

10 7 11 7.5

12 8 13 8.5

14 9 15 9.5

16 10 17 10.5

18 11 19 11.5

20 12 21 13 22 14 23 15 24 16 25 17 26 18 27 19