EMBRYOLOGY
J
Bf
-
wmm
H
I
.4
Number
of
0
Incu bation ti me in ho
accordin g to:—
Huettner Patten
Stage *
Duval
somites
4
20
17-18
18
Anterior
imal
i
length,
cida.
5
21
19
20
Mesoderm, somites
and kidney
Nervous system
’rimitive streak
Lillies
18-19
i.e.,
0
REFERENCE TABLE OF
19-22
"
|
6
6
Vascular system
intestinal
portal
shaped
sheet of
mesoderm
spreads
out
laterally from the primi-
Shield
2.2
0.7 of area
Groove, pit
^^mode present.
tive streak.
Neural plate and neural
to decrease in
1.9 mm. Noto- folds visible.
grows forward
’n^Pnode.
Lateral horns of mesoderm
grow forward. The first
somite may appear simultaneously with the formation of the head fold ( stage
Mesenchyme
cells form
isolated
in extra-embryonic
mesoderm.
First
seen
to be present.
The blood islands begin to unite and
the first blood corpuscles are produced within the resulting tubes.
as the foregut elon-
blood
islands
7).
3
8
22
23
23
25-28
Reduced
1.5
to
a length of
mm.
Neural folds meet in brain
region but do not fuse.
Lateral horns grow round
the mesodermless proamnion. Segmented somites
joined to lateral plate mesoderm
intermediate
by
mesoderm
A
Moves back
gates.
nephrotome ).
cavity, the myocoel, ap(
pears in somites.
5
8+
23-25
25
25-26
27-30
1.2
mm.
long.
Fusion of fclvL
bcgi..^
ir.
brain region; further back
neural folds meet but they
splay out over the somites.
T.'.c
meet
10
13
10
11
29-30
33-34
30
33
30-31
33-34
33-38
40-45
0.6
0.4
mm.
mm.
long.
long.
37-41
37
38-40
46-50
0.2
mm.
long.
43-46
43
44-48
48-52
No
longer distinguishable: contributes material to tail bud.
Lies posterheart prim-
with
ventral
and
dorsal
material between somites
six and ten. The first somite
begins to disappear.
Five brain vesicles can be
seen. Anterior neuropore
closes. The neural folds fuse
thirteenth
the
Fore brain at an angle to
hind brain due to flexure. A
shallow infundibulum is
The dorso-lateral buds differentiate into pronephric
tubules and the pronephric
duct forms by fusion of
material from the tubules.
First signs of Wolffian duct.
Connection between somites and nephrotomes is lost.
The mesonephros develops
pronephros
along
with
below the somites. Wolffian
duct extends from tenth to
Jifteenth somite. Differentiation begins in anterior
somites.
14 +
.-»hryr> t'c'-omes linked to the
?
together
aortae.
The intermediate meso- The heart primordia fuse to form a
derm begins to separate off tubular heart which bends slightly to
dorsally. The pronephric
the right of the embryo. Faint and
tubules develop from this sporadic pulsation of the heart occurs.
present.
21
V
blood island system by vitelline veins.
Paired primordia of the heart develop
cles visible.
somite.
12 +
son :‘cs
cf
Fore brain at
right angles
to hind brain. Fore brain
enlarges
in
telencephalon
region.
ior
the
to
ordia.
anteriorly.
Except for anterior neuropore, fusion offolds is completed in the brain region.
Three primary brain vesi-
beyond
17
v’vm-
become radially arranged
about the myocoel cavities;
cavity reduced by a central
core of cells. Lateral horns
Pronephros begins to
appear anterior to
dis-
the
eleventh somite. In the ansomites
a distinct der-
terior
matome can be
seen
and
The heart becomes
distinctly dis-
placed to the right. The rate and amplitude of the heart beats increase. A
network of blood vessels established
in area vasculosa.
The heart is beating efficiently by
this stage and blood circulates. The
heart is S-shaped. The first aortic
arch begins to develop. The dorsal
aortae fuse between somites three
and four. The vitelline artery can be
seen between somites sixteen and
seventeen.
The atrium begins to divide into right
auricles. The first aortic arch
is established and the second begins
to form. Fusion of dorsal aortae may
reach somite eight. The vitelline
and left
cells
migrate from the
somites and neural crests to
the sclerotomes round
the notochord.
artery
17-19.
The posterior somites remain undifferentiated; an-
Besides the two auricles heart has
distinct ventricle and conus arteriosus. Two aortic arches present.
Dorsal aortae fuse as far back as
somite twelve. The vitelline arteries
lie between somites eighteen and
twenty.
is
May
reach
the
first
somite.
Reaches the
second
somite.
Reaches the
third
somite.
Reaches the
fourth
somite.
distinct between somites
form
24
15
44-46
48
48-50
The telencephalon becomes
the
diendistinct from
50-55
cephalon. Rathke’s pocket
grows under the infundibulum.
27
16
48
50-52
50-55
Telencephalon and diencephalon become separated
by the velum transversum.
A distinct isthmus can be
seen between the mesencephalon
and metence-
51-56
teriorly
tiate into
somites
differen-
dermatome, myo-
tome and sclerotome. There
are eleven pairs of mesonephric tubules between
somite five and sixteen.
Differentiation
matome,
into
der-
myotome
and
sclerotome reaches somite
twenty. Wolffian duct and
mesonephric tubules seen in
trunk sections.
phalon.
30
17
52
58-60
55-60
S2-6m
1
deepens.
The
isthmus
Paired telencephalic vesicles
develop. Roof of hind brain
becomes very thin in myelencephalon region. Brain
bent double by now.
36
18 +
68-72
72
72
72
1
The cerebral hemispheres
develop from the telencephalic vesicles. The inwith
fundibulum
joins
Rathke's pocket to form
the pituitary.
i
The third aortic arch appears. The
dorsal aortae fuse between somites
four and fourteen. The vitelline
artery lies between somites 19 and
21.
Vitelline
ductus
veins
venosus
join
which
to
opens
Is
the
in
region
of
somites five
to six.
Lies
between somites
seven
and ten.
form
into
sinus venosus.
Differentiation reaches the
twenty-fifth somite. Wolffian duct grows back towards cloaca. Glomeruli
can be seen
in
mesonephric
tubules.
Differentiation reaches the
somite. Wolffian
thirtieth
duct
may
later.
reaches
cloaca
not fuse with
it
but
until
There are three complete aortic
arches and the fourth begins to
develop. The first pair of uortic
arches may begin to atrophy at this
stage. Dorsal aortae fused up to
somite 16. Vitelline artery between
somites 20 and 22.
The first pair of aortic arches continue to atrophy as the fourth pair
develop. Dorsal aortae fused as far
back as somites 17-20. Vitelline
artery is in region of somites 21-22.
Has moved
back to
between
lie
somites ten
and
twelve.
Between
somites
thirteen
and
fourteen.
CHICK DEVELOPMENT
SEATTLE
qcq i 3 F877A
Alimentary system
PUBUCUBRARV qi0U7
031
ExiSSL.
Eyes
0 000l040
Foregut 0.15
mm.
.asr
^H
e
c
i&
long.
Foregut 0.3 to 0.4
mm.
long.
Foregut 0.5 to 0.8
mm.
long.
Foregut about 1.0
mm.
lung.
SEATTLE PUBLIC LIBRARY
REFERENCE BOOK
NOT TO BE TAKEN FROM THIS ROOM
Foregut is about 1.3 mm. long.
R591.3
P877A
2194015
The remains of the
primitive
streak
begin
contributing
material posteriorly
to the tail bud.
is 1.5 mm. long
there are indications of
the first pair of visceral clefts.
The foregut
and
The first pair of visceral clefts
are distinct and the second
pair begin to form.
first and second visceral
clefts are clearly visible; the
third pair begin to develop.
The hind gut appears.
The
The lens rudiments
in-
vaginate to form lens
vesicles. The optic vesicles invaginate to form
optic cups
The mouth of each
auditory pit begins
to
and
constrict
auditory
vesicles
form.
The mouth of the lens
The mouth of the
vesicle begins to close.
auditory
vesicle
is
reduced to a small
aperture.
Cranial flexure, i.e. angle
between fore- and hindbrain, is 90°. Cervical flexure begins in hind-brain
region and trunkflexure can
also be seen.
Cranial flexure causes the
fore-brain to be directed
backwards close to the
heart.
Cervical flexure
The head
is
fully
turned to the left.
The first five to seven
somites also exhibit
torsion.
Torsion is apparent
in somites eight to
ten.
becomes a broad curve.
The
second and third
first,
visceral
The
clefts
liver
are
present.
bud appears as do
and anal plate.
the tail gut
The
lens
becomes cut off
from the ectoderm. The
cups
optic
are
almost
The retina disThe eye is still an-
closed.
tinct.
terior to the ear.
The fourth pair of visceral
The liver bulge
conspicuous. Tail gut
further into tail.
clefts develop.
is
now
extends
The optic cup
eyes now
the ears.
lie
closes.
The auditory
vesicle
is connected to the
small
ectodermal
aperture
the
by
ductus endolympha-
Cranial flexure is at its
maximum. Cervical flexure
increases. Trunk flexure is
noticeable in the region of
somites ten to twelve.
Torsion extends to
somites eleven,
twelve and thirteen
or even further.
The aperture
closes.
posterior to
Cloaca begins to form.
Cranial flexure remains unchanged. Cervical flexure is
about 100 °. Trunk flexure
develops into a broad curve.
Caudal flexure begins.
Torsion as far back
as somites fifteen to
Caudal flexure causes tail
be at an angle of 90° to
The whole posterior
region exhibits some
degree of torsion.
nineteen.
Lung buds develop.
The eyes, due
The auditory
lie
pear-shaped with
a narrow ductus en-
to flexure,
well posterior to the
vesicle
is
dolympha ticus.
to
the body.
The
The sero-amniotic connection is somewhat
attenuated. The amnion covers somites six
to thirteen. Tail fold
appears.
a
distinct
The head fold has extended to the region
between somites sixteen
to
twenty-four.
The tailfold has grown
forward over som-
oval aperture
somites 26-28.
over
bud begins
The tail bud can be
seen projecting behind the hind gut.
limb
The
buds
appear as low swellings.
Begins as an
outgrowth
of
the hind gut in
the cloacal region.
29-30.
The head and tail folds
meet or leave a small
tail
to develop posterior
to the hind gut.
The head fold grows
back and may lie anywhere between somites
ten and eighteen. The
ites
Four pairs of visceral clefts.
The tail gut begins to degenerate. The anterior and posterior
intestinal portals approach
each other, leaving an open
intestinal umbilicus of 3 mm.
is
bud.
tail
Tail folds may begin to
develop.
tailfold begins to grow
forward.
ticus.
The
There
The hind brain andfirst
few somites are covered by the amnion.
The
tail bud begins
curve forward.
The fore limb bud
between somites
17-19 and the hind
limb bud between
somites 26-30.
to
lies
Allantoic stalk
Limb buds are now
and
quite
vesicle.
The vesicle enlarges after 72
hours.
conspicuous
and begin to exhibit
nipple-shaped apices
The hind limb bud
extends to somite
32.
An
Atlas of
f(
Embryology
by
W.
H.
FREEMAN,
1
Head of
B.Sc.,
\\
the Biology Department, Chislehurst and Sidcup
Grammar
School,
Chief Examiner, ‘A’-level Zoology, London
and
BRIAN BRACEGIRDLE,
Senior Lecturer
in
Biology, St Katharine’s College, London,
Assistant Examiner, ‘A'-level Zoology, London
HEINEMANN
LONDON
B.Sc., a.r.p.s.,
Heinemann Educational Books Ltd
LONDON MELBOURNE TORONTO
TOWN SINGAPORE
AUCKLAND IBADAN
HONG KONG
CAPE
© W.
H. Freeman
&
Brian Bracegirdle 1963
First published 1963
Reprinted 1964
77
Ft
Published by Heinemann Educational Books Ltd
15-16
Queen
Printed
in
Street, Mayfair,
London W.l
Great Britain by
Bookprint Limited, Kingswood, Surrey
SEATTLE PUBLIC LIBRARY
Preface
This book consists of photomicrographs of sectioned and entire embryos of frog and chick,
with large detailed drawings to correspond.
Descriptive embryology is still recognised as a necessary and valuable part of courses
in zoology and biology leading to the General Certificate of Education
at Advanced Level,
and to first degrees. As teachers and examiners we have become aware of the difficulties
experienced by students in interpreting the embryological structures seen under the
microscope. The present book is intended to help overcome these difficulties, while at the
same time summarising the descriptive embryology of frog and chick in sufficient detail
for degree level. Care has been taken to label fully, and to make the drawings and
photographs large enough for clearness.
It has become apparent that the embryology slides in
general use are not of very high
attempt was made to obtain slides of better quality, but to
use those normally confronting the student - in this way we hope to have improved the
chances of artifacts being recognised as such. A large number of slides was looked through,
but in the end we confined ourselves to a relatively small number of the more typical
quality. For this reason, little
specimens. By doing this we were able to produce a book inexpensive enough for wide
general use.
Each slide was photographed through the microscope, with special attention being
paid to securing a flat field and good depth of focus - especially difficult with these rather
large specimens. Not all the slides selected for inclusion were of a quality desirable for
photomicrography, as will be obvious from the photomicrographs themselves; but we feel
that this need be no great drawback, since students are often required to interpret these
poorer-quality slides.
Each drawing was made completely independently of the photograph, directly from the
An accurate outline was obtained by microprojection, with the emphasis on line
work, as it should be in students’ drawings. Where it made for greater clarity, the drawing
was diagrammatised, as in the case of some of the embryonic membranes. Later the drawing
was compared with the photograph, and dotting was added where it seemed desirable for
greater clarity. It will be seen that more detail appears in many of the drawings than in
the corresponding photographs. This detail is obtainable only by the proper use of the fine
focusing of the microscope at increased magnification, and should serve as a salutary
reminder to the student that it is necessary for him to do the same to interpret his slides!
Much care and effort has been expended on the labelling of the drawings, and all the
usual texts have been consulted. Even so, it was often necessary to have recourse to serial
sections, where these were available. In many cases, none were, and so some errors are
likely to remain, even though we were fortunate to have the fullest
co-operation of Dr
Ruth Bellairs, of University College, London, in checking the work. We are most grateful
to Dr Bellairs for her great help; any errors remaining are, of course, the entire responsislide.
bility of
the authors.
It would not have been possible to have produced
this work from the slides already in
our possession. For their kindness in making available extra material, we are deeply
indebted to the following: Mr Charles Biddolph, Mr C. V. Brewer, Dr Ben Dawes, Mrs
J. Froud, Mr George Gardener, Mr A. T. Green, Mr C.
Fleather, Dr Brian Lofts, Mr C. T.
Pugsley, Mr A. R. Tindall, Mr H. Whate, and the Zoology Department of Wye College
To
'
TECHNOLOGY
1965
7
2
SEP
2194015
6
Mr George Gardener we owe
an additional debt for his early criticism and encouragement.
were likewise fortunate in our lettering artist, Mr Alan Plummer, who co-operated in
most wholehearted manner; and also in our Publishers - in Mr Alan Hill and Mr Hamish
MacGibbon we found a most sympathetic support and facilitation of our aims. Last, but very
definitely not least, we must thank our wives very sincerely indeed for their help and
encouragement, and for their stoicism when surrounded for weeks on end by all the
impedimenta of drawing and photomicrography.
We
a
W.H.F.
September
1
962
B.B.
Contents
Frog: cleavage, 2-cell stage, V.S.
2 Frog: cleavage, furrows, V.S.
40 Chick: 6-somite stage, somitic region,
1
3
Frog: cleavage,
1
T.S.
6-cell stage, V.S.
Chick: 6-somite stage, notochord, T.S.
42 Chick: 6-somite stage, primitive streak,
41
4 Frog: cleavage, 24-cell stage, V.S.
5 Frog: cleavage, blastula, V.S.
6 Frog: early gastrula (dorsal
lip),
T.S.
43 Chick: 6-somite stage, V.L.S.
44 Chick: 10-somite stage, V.L.S.
45 Chick: 0-somite stage, forebrain region,
V.S.
7 Frog: later gastrula (yolk plug), V.S.
8 Frog: later gastrula (yolk plug), H.S.
9 Frog: neural plate stage, T.S.
10 Frog: neural fold stage, T.S.
1
T.S.
46 Chick:
12
Frog, neural tube stage, T.S.
Frog: neural, V.L.S.
13
Frog: newly-hatched larva, optic region,
1
1
T.S.
47 Chick:
T.S.
14 Frog:
newly-hatched
larva,
auditory
16
Frog: external
Frog: external
gill
larva,
optic region,
T.S.
larva,
gill
larva, heart
gill
larva,
gill
larva,
and
T.S.
brain, T.S.
gill
region, T.S.
53 Chick: 24-somite stage, fore and hind
Frog: external
trunk region,
T.S.
brain, T.S.
54 Chick: 27-somite stage, trunk region,
20 Frog: external
head
region,
H.L.S.
21
T.S.
55 Chick: 27-somite stage, posterior trunk
Frog: external
gill
larva,
trunk region,
gill
larva,
trunk region,
H.L.S.
region, T.S.
56 Chick:
22 Frog: internal
V.L.S.
27-somite stage,
eye
and
ear
region, T.S.
57 Chick: 30-somite stage, fore and hind
23 Frog: internal
gill
larva,
optic region,
T.S.
brain, T.S.
58 Chick: 30-somite stage,
24 Frog: internal
gill
larva, gill region, T.S.
25 Frog: 19-mm tadpole, forelimb region,
heart
region,
T.S.
59 Chick: 30-somite stage, anterior trunk
T.S.
26 Frog:
3-somite stage, posterior trunk
17-somite stage, trunk region,
52 Chick: 24-somite stage, fore and hind
18 Frog: external
19
1
Chick: 21-somite stage, trunk region,
auditory region,
T.S.
region,
T.S.
51
gill
region,
heart
region, T.S.
50 Chick:
17
heart
13-somite stage,
T.S.
49 Chick:
Frog: newly-hatched larva, trunk region,
T.S.
10-somite stage,
T.S.
48 Chick:
region, T.S.
15
0-somite stage, hindbrain region,
1
region, T.S.
19-mm
tadpole,
trunk
region,
60 Chick: 30-somite stage, posterior trunk
T.S.
region, T.S.
27 Chick: blastoderm, head-process stage,
61
Chick:
E.
36-somite
pharyngeal
stage,
region, T.S.
28 Chick: blastoderm, head-fold stage, E.
29 Chick: blastoderm, 3-somite, E.
30 Chick: blastoderm, 6-somite, E.
31 Chick: blastoderm, 10-somite, E.
32 Chick: blastoderm, 13-somite, E.
33 Chick: blastoderm, 17-somite, E.
34 Chick: blastoderm, 20-somite, E.
35 Chick: blastoderm, 25-somite, E.
36 Chick: blastoderm, 30-somite, E.
37 Chick: blastoderm, 35-somite, E.
38 Chick: blastoderm, 40-somite, E.
39 Chick: 6-somite stage, head region, T.S.
62 Chick:
36-somite
stage,
hind-brain
region, T.S.
63 Chick:
36-somite
olfactory
stage,
pit
region, T.S.
64 Chick: 36-somite stage, optic region,
T.S.
65 Chick: 36-somite stage, trunk region,
T.S.
66 Chick: 45-somite stage,
limb region, T.S.
tail
67 Chick: 36-somite stage, H.L.S.
A reference table of chick development
is
printed on the end-papers
and hind-
Frog: cleavage,
2-cell stage, V.S.
Frog: cleavage,
16-cell stage, V.S.
mag. 50 X
mag. 50 x
2.
4.
Frog: cleavage furrows, V.S. mag. 50 X
Frog: cleavage,
24-cell stage, V.S.
mag. 50 x
I,
SMALL AMOUNT
OF YOLK IN
MICROMERES
MICROMERES
BLASTOCOEL-
BLACK
PIGMENT
YOLKY
CELLS OR
MEGAMERES
YOLK
GRANULES
VEGETATIVE
POLE
VITELLINE
MEMBRANE
5.
6
.
Frog: cleavage,
blastula, V.S.
Frog: early gastrula (dorsal
lip),
mag. 45
X
V.S. mag. 40
Drawing
X
2, 3, 4, 5,
ANIMAL POLE
of
specimen 5
6
7,8
DORSAL SURFACE
PRESUMPTIVE
CHORDA- MESODEI
ARCHENTERON
PRESUMPTIVE
IN VAOINATING
CELLS
NEURAL PLATE
DORSAL LIP OF
BLASTOPORE
YOLKY
ENDODERM
BLASTOPORE
CELLS
ANTERIOR
POSTERIOR
ECTODERM
VENTRAL
LIP
BLASTOPORE
BLASTOCOEL
VENTRAL
MESODERM
VENTRAL SURFACE
Drawing of specimen 7
Drawing
of specimen 8
OF
9.
Frog: neural plate stage,
I
I
.
Frog:
neural tube stage, T.S.
mag. 42 X
T.S.
mag.
35x
10.
Frog: neural
fold stage, T.S.
mag.
35x
9, 10, II
NOTOCHORD
''SOMITE
NEURAL PLATE
- NEURAL FOLD
-
OUTER LAYER
ECTODERM
NEURAL CREST
OF
NEURAL GROOVE
x
DORSAL
NEURAL FOLD
NEURAL CREST
NEURAL PLATE
NOTOCHORD
CRANIAL GANGLION
( appears before
the neural Folds
INNER LAYER
r
e
OF ECTODERM.
met in Froj)
DERIVED FROM NEURAL
ARCHENTERON (OUT)
CREST
COELOM
SOMITE
V (The separation
CRANIAL
GANGLION
'between these
layers
is
an
SOMATIC
SPLANCHNIC
MESODERM
MESODERM
DERIVED
artefact)
FROM NEURAL
CREST
MESODERM
ARCHENTERON
(GUT)
ENDODERM
YOLKY
ENDODERM
YOLKY
ENDODERM
ECTODERM
VITELLINE
MEMBRANE
VENTRAL
VENTRAL
Drawing of specimen
9
Drawing of specimen
SEPARATION OF ECTODERM INTO
LAYERS IS AN ARTEFACT
NEURAL TUBE
TWO
these layers are normally
in
NEURAL CANAL
contact
NEURAL CREST
SOMITE
10
NOTOCHORD
<
-ECTODERM
LATERAL PLATE
MESODERM
COELOM
ENDODERM
ARCHENTERON
BREAK
YOLKY
IN
ENDODERM
TISSUE
.CELLS
VENTRAL
Drawing of specimen
I
I
60x
mag.
V.L.S.
neurula,
Frog:
12.
BRAIN)
(HIND
RHOMBENCEPHALON
55
larva,
mag.
newly-hatched
T.S.
region,
Frog:
auditory
14.
larva,
80x
mag.
newly-hatched
T.S.
region,
Frog:
13.
optic
13,
C
<u
£
u
<u
Q-
txO
c
>
LAYER
PIGMENTED
o
M
NEUROCOEL
NEURAL TUBE
LARGE
VACUOLATED CELLS
SUBNOTOCHORDAL
NOTOCHORD
ROD
SOMITE
DORSAL AORTA
NEPHROSTOME
GLOMUS
PRONEPHRIC
DUCT
POSTERIOR
CARDINAL
PRONEPHRIC
SINUS
TUBULES
ENDODERMAL
LAYER OF
INTESTINE
MESODERMAL
LAYEROF
INTESTINE
PERITONEUM
HEPATIC VEIN
Drawing
of
specimen
15
14
l
15
lOOx
mag.
T.S.
region,
optic
larva,
gill
external
Frog:
16.
I
16
EPITHELIUM
PIGMENTED
CAROTID
VENTRAL
ARTERY
I00x
mag.
T.S.
region,
auditory
larva,
gill
external
Frog:
17.
17
ARTERIOSUS
TRUNCUS
<D
Oto
O
bO
I20x
mag.
T.S.
region,
gill
and
heart
larva,
gill
external
Frog:
18.
18
VENTRICLE-
1
CAVITY
PERICARDIAL
VENTRICLE
4TH
OF
ROOF
80x
mag.
T.S.
region,
trunk
larva,
gill
external
Frog:
19.
OBLONGATA
MEDULLA
19
specimen
of
Drawing
1
20.
Frog: external
gill
larva,
head region, H.L.S. mag. 85
21.
Frog: external
gill
larva,
trunk region, H.L.S. mag. 50x
20, 21
MESENCHYME FORMING
CHOROID
AUDITORY VESICLE
OLFACTORY
ANTERIOR
CARDINAL
PIT
VEIN
HIND BRAIN
VIITH
CRANIAL
FORE
GANGLION
BRAIN
VTH CRANIAL GANGLION
OLFACTORY
PLACODE
ANTERIOR CARDINAL VEIN
Drawing
of
specimen 20
EXTERNAL
OESOPHAGUS CLOSED
BY PLUG OF CELLS
DORSAL AORTA
MYOTOMES
PRONEPHRIC BULGE
NOTOCHORD
STOMACH
-PHARYNX
GILL
-DORSAL AORTA
-INFUNDIBULUM
OLFACTORY
ORGAN
TAIL
COELOM
POSTERIOR CARDINAL SINUS
NEPHROSTOME
TELOCOEL
PRONEPHRIC TUBULES
VISCERAL ARCHES
—
AORTIC ARCHES
VTH, VIITH & IXTH
CRANIAL GANGLIA”
Drawing
of specimen 21
TELENCEPHALON
OPTIC CUPP-
1
L- LENS
22
specimen
of
Drawing
80x
mag.
T.S.
region,
optic
*
larva,
gill
internal
Frog:
23.
23
s
-7
LU
45
mag.
T.S.
region,
Gill
larva,
gill
internal
Frog:
;
24.
24
L-U
<N
c
a>
£
u
<L>
CL
00
O
00
c
£
fd
Q
CARTILAGE-
PARACHORDAL
c
35x
mag.
T.S.
region,
forelimb
tadpole,
19-mm.
Frog:
25.
25
40x
mag.
T.S.
region,
trunk
tadpole,
19-mm.
Frog:
26.
26
26
specimen
of
Drawing
25x
mag.
E.
stage,
head-fold
blastoderm,
Chick:
28.
25x
mag.
E.
stage,
head-process
blastoderm,
Chick:
27.
29.
Chick: blastoderm, 3-somite,
E.
mag.
40x
2
-A
PROAMNION
V
BORDEROF
ANTERIOR
INTESTINAL
PORTAL
ECTODERM OF
HEAD FOLD
FORE BRAIN
fur"
(
FORE GUT
LATERAL
J
HORN OF
MESODERM
LATERAL HEAD FOLD
c
_
NEURAL FOLD
NOTOCHORD
c
AMNIO-CARDIAC
VESICLE
AREA PELLUCIDA
INTERSOMITIC
1ST "SOMITE
FURROW
FOLD
IN
BLASTODERM
FOLD
3RD SOMITE
IN
BLASTODERM
'ARTEFACT;
LATERAL
PLATE MESODERM
HENSEN'S NODE
AREA OPACA
BLOOD
ISLANDS
PRIMITIVE
BEG INN INC
'STREAK
TO LINK UP
TO FORM
BLOODVESSELS
SINUS TERMINALS
Drawing of specimen 29
30.
Chick: blastoderm, 6-somite,
E.
mag.
40x
LATERAL HORNS OF MESODERM
ANTERIOR NEUROPORE
PROAMNION
HEAD RAISED UP ABOVE PROAMNION
ENDODERMAL WALL OF FORE OUT
PROSENCEPHALON OR FORE BRAIN
CAUDAL EXTENT OF FREE HEAD
ECTODERM
OF HEAD FOLD
VITELLINE VEIN & HEART
AMNIO-CARDIAC VESICLE
PRIMORDIA
EXTRA -EMBRYONIC AREA
BORDER OF
ANTERIOR
INTESTINAL
PORTAL
NEURAL FOLDS
BEGINNING
TO FUSE
NEURAL FOLDS
SPLAYING OUT
BOUNDARY
OF
AREA
PELLUCIDA
MESODERM
EMBRYONIC AREA
AREA OPACA
INTER-SOMITIC
1ST
FURROW
SOMITE
6TH SOMITE
NOTOCHORD
UNSEOMENTED
MESODERM
TRIMMED EDGE
HENSEN'SNODE
THE
BLASTODERM
THAT HAS BROKEN
PIECE OF
PRIMITIVE
FOLD
PRIMITIVE
STREAK'
PRIM
l
AWAY AND BEEN
GROOVE
DISPLACED
MARGIN OF
BLOOD VESSELS FORMING
IN AREA VASCULOSA
AREA VASCULOSA
Drawing of specimen 30
31.
Chick: blastoderm, 10-somite,
E.
mag.
45x
ANTERIOR NEUROPORE
FORE BRAIN OR
PROAMNION -
PROSENCEPHALON
ECTODERM
OPTIC VESICLE
ENDODERM
OF HEAD
FORE OUT
OF FOREOUT
HEART
MID BRAIN OR
BORDER OF
ANTERIOR
MESENCEPHALON
INTESTINAL
HIND BRAIN OR
PORTAL
RHOMBENCEPHALON
SOMITES
NEURAL FOLDS
NOTOCHORD
AREA
RHOMBOIDALIS
HENSEN'S
NODE
UNSEOMENTED
MESODERM
LATERAL PLATE
MESODERM
PRIMITIVE
PRIMITIVE
STREAK
GROOVE
PRIMITI
FOLD
SINUS TERMINALS
ROUND BOUNDARY
OF AREA VASCULOSA
AREA VASCULOSA
BLOOD VESSELS
OVER YOLK
Drawing of specimen
31
(Drawn from ventral aspect; photograph
is
of dorsal aspect)
-
32.
Chick: blastoderm, 13-somite,
E.
mag. 35x
ECTODERM
OF HEAD
HEAD AMNIOTIC FOLD
ENDODERM
OF FORE OUT
CLOSED NEUROPORE
VENTRAL AORTA
FORE BRAIN OR PROSENCEPHALON
TRUNCUS ARTERIOSUS
OPTIC
VESICLE
AUDITORS PLACODE
FORE GUT
FUSION OF
VITELLINE VEINS
MID BRAIN OR
MESENCEPHALON
HINDBRAIN OR
RHOMBENCEPHALON
PROAMNION
HEART
VITELLINE
VEIN
BORDER OF
ANTERIOR
LATERAL
MESODERM
INTESTINAL
PORTAL
SOMITES
NEURAL TUBE
AREA VASCULOSA
SINUS TERMINALS
FORMING THE
BOUNDARY OF
AREA VASCULOSA
POSTERIOR
CARDINAL VEIN
DEVELOPING
UNSEGMENTED
PARAXIAL
VITELLINE ARTERY
MESODERM
LATERAL PLATE
MESODERM
DISAPPEARING
PRIMITIVE STREAK
Drawing of specimen 32
33.
Chick: blastoderm, 17-somite,
E.
mag. 30x
ECTODERM OF HEAD
HEAD SHOWING TORSION
PROSENCEPHALON
MID-BRAIN OR
MESENCEPHALON
OPTIC VESICLE
LEFT ANTERIOR
VITELLINE VEIN
CRANIAL FLEXURE
METENCEPHALON
MARGIN OF AMNION
FORE GUT
MYELENCEPHALON
RIGHT ANTERIOR VITELLINE
TRUNCUS ARTERIOSUS
AUDITORY PLACODE
INVAGINATING TO
FORM AUDITORY PIT
FIRST
VEIN
VENTRICLE
ATRIUM
TWO
SOMITES SHOWING
SLIGHT TORSION
VITELLINE VEIN
BORDER OF
ANTERIOR INTESTINAL
PORTAL
SOMITES 6
&7
NETWORK OF
BLOOD VESSELS IN
AREA VASCULOSA
NEURAL TUBE
POSTERIOR
CARDINAL VEIN
VITELLINE ARTERY
SOMITE
17
LATERAL PLATE
MESODERM
RHOMBOIDAL SINUS
PRIMITIVE STREAK
PRACTICALLY GONE
Drawing of specimen 33
34
(Left) 34.
Chick: blastoderm, 20-somite,
E.
mag. 40x
*
:
35.
Chick: blastoderm, 25-somite,
E.
mag.
45x
MESENCEPHALON
LEFT ANTERIOR
VITELLINE VEIN
CAVITY
OF
THE MOUTH
ISTHMUS
DIENCEPHALON
METENCEPHALON
EYE
PHARYNGEAL
LENS
MEMBRANE
OPTIC CUP
THIN ROOF DF
HIND BRAIN
MYELENCEPHALON
1ST VISCERAL POUCH
DUCTUS ENDOLYMPHATICUS
AUDITORY VESICLE
2ND VISCERAL POUCH
1ST AORTIC
ARCH
TELENCEPHALON
2ND AORTIC ARCH
3RD VISCERAL POUCH
PHARYNX
TRUNCUS ARTERIOSUS
VENTRICLE
ATRIUM
RIGHT ANTERIOR
VITELLINE VEIN
TORSION APPARENT
IN
SOMITES 10 &
11
MARGIN OF ANTERIOR
INTESTINAL PORTAL
SOMITE
12
MARGIN OF AMNION
LATERAL AMNlOTlC FOLD
NEURAL TUBE
POSTERIOR CARDINAL VEIN
VITELLINE ARTERY
SOMITE 25
TAIL BUD
TAIL
Drawing of specimen 35
AMNlOTlC FOLD
36.
Chick: blastoderm, 30-somite,
E.
mag.
25x
RIGHT ANTERIOR
VITELLINE VEIN
METENCEPHALON
ISTHMUS
LEFT ANTERIOR
VITELLINE VEIN
AMNION
'
MESENCEPHALON
DUCTUS
CRANIAL FLEXURE
ENDOLYMPHATiCUS
MOUTH CAVITY
MVELENCEPHALON
POSITION OF
AUDITORY VESICLE
INFUNDIBULUM
— DIENCEPHALON
OPTIC CUP
LENS
JELENCEPHALON
AORTIC ARCH
2ND AORTIC ARCH
1ST
^—7
-
3RD AORTIC ARCH
ATRIUM
TRUNCUS ARTERIOSUS
SINUS VENOSOS
^
-VENTRICLE
ANTERIOR
INTESTINAL PORTAL
ftt&HT VITELLINE VEIN
or 01
SOMITE
<f
18
MARGIN OF AMNION
VITELLINE ARTERY
X-
POSTERIOR CARDINAL
VEIN
SOMITE 29
SOMITE 30
SEPARATING
TAIL BUD
TAIL AMNIOTIC
FOLD
Drawing
of specimen 36
ANTERIOR CARDINAL VEIN
RIGHT ANTERIOR VITELLINE VEIN
AMNION
ANTERIOR VITELLINE VEIN
1ST VISCERAL POUCH
DUCTUS ENDOLYMPHATIQUS
2ND VISCERAL POUCH
AUDITORY VESICLE
3RD VISCERAL POUCH
THIN ROOF OF
MYELENCEPHALON
4TH VISCERAL POUCH
PHARYNX
VTH CRANIAL (GASSERIAN)
GANGLION
METENCEPHALON
2ND VISCERAL ARCH
ISTHMUS
4TH AORTIC ARCH
RIGHT AURICLE
-MESENCEPHALON
CUVIERIAN DUCT
1ST VISCERALARCH
SINUS VENOSUS
TRUNCUS ARTERIOSUS
S<L
NOTOCHORD
POSTERIOR CARDINAL
VEIN
INFUNDIBULUM
CHOROID FISSURE
VENTRICLE
LIVER BULGE
EYE
LENS
ANTERIOR INTESTINAL
OLFACTORY PIT
PORTAL BORDER
blEN CEPHALON
CEREBRALHEMISPHERE
EPIPHYSIS
TELENCEPHALON
FORE LIMB BUD
DORSAL AORTA
POSTERIOR CARDINAL VEIN
VITELLINE VEIN
VITELLINE ARTERY
HIND LIMB BUD
NEURAL TUBE
SOMITE 28
CLOSURE OF
AMNION
ALLANTOIC VESICLE
ALLANTOIC STALK
SOMITE 35
AMNION
Drawing of specimen 37
38.
Chick: blastoderm, 40-somite,
E.
mag. 30 x
38
PHARYNX
3RD VISCERAL POUCH
MYELENCEPHALON
4TH VISCERAL POUCH
AUDITORY VESICLE
RIGHT AURICLE
DUCTUS ENDOLYMPHATIC
DORSAL AORTA
GENICULATE <VII> &
ACUSTICO <VIID GANGLIA
POSTERIOR
CARDINAL VEIN
THIN ROOF OF
MYELENCEPHALON
ANTERIOR CARDINAL
LEFT AURICLE
1ST VISCERAL
LIVER BULGE
TRUNCUS
VEIN
POUCH
2ND VISCERAL ARCH
ARTERIOSUS
1ST VISCERAL ARCH
AMNION
VTH CRANIAL
'GASSERIAN) GANGUON
VTH CRANIAL NERVE
(OPHTHALMIC BRANCH)
METENCEPHALDN
VENTRICLE
ISTHMUS
FORE LIMB BUD
INFUNDIBULUM
SOMITE 16
BORDEROF
MESENCEPHALON
EYE
'
ANTERIOR
LENS
INTESTINAL
DIENCEPHALON
PORTAL
.
ECTODERM OF HEAD
EPIPHYSIS
VITELLINE_
VEIN
TELENCEPHALON
VITELLINE
CEREBRAL HEMISPHERE
ARTERY
OLFACTORY
PIT
POSTERIOR
CARDINAL VEIN
TAIL
SOMITE 40
HIND LIMB BUD
NEURALTUBE
SOMITE 30
ALLANTOIC VESICLE
ALLANTOIC STALK
Drawing
of
specimen 38
40.
Chick: 6-somite
41.
stage, somitic region, T.S.
Chick: 6-somite
stage, notochord, T.S.
mag. 200x
mag. 225x
at
it?
C
&iQ*9w****
%* •***
gS&8r
r*
%
f****
42.
Chick: 6-somite
Y
~
11
*
:i
|£*
*
•*
%?
stage, primitive streak, T.S.
**
*
#-
%
*
» t
*
* *
*
**
«
mag. 200x
- #t
^
39 40 41 , 42
,
,
NEURAL FOLDS
BRAIN
PHARYNGEAL REGION
HEAD REGION
'OF
FOREGUT
ECTODERM
SOMATIC MESODERM
SOMATOPLEURE
SPLANCHNOPLEURE
SPLANCHNIC MESODERM
AMNIO-CARDIAC
ENDODERM
VESICLE
OPEN ENTERON
Drawing
of specimen 39
NEURALGROOVE
SOMITE
NEURAL FOLD
MESENCHYME FORMING
CENTRAL CORE OF CELLS
DORSAL AORTA
ECTODERM
SOMATIC
MESODERM
——SOMATOPLEURE
COELOM
SPLANCHNOPLEURE
SPLANCHNIC MESODERM
OPEN ENTERON
ENDODERM
Drawing
of specimen 40
PRIMITIVE
STREAK
— MESODERM
Drawing of specimen 42
ENDODERM
28x
mag.
U.L.S.
stage,
10-somite
Chick:
44.
43, 44
C
<L>
Q)
E
E
u
<L»
a)
Q.
CL.
l/>
w»—
O
O
&0
£
Cl
Q
c
£
a
Q
45.
Chick: 10-somite
stage, forebrain region, T.S. mag.
46.
Chick: 10-somite
stage, hindbrain region, T.S.
lOOx
mag. 200x
45, 46
PROSENCEPHALON
-
HEAD FOLD OF AMNION
HEAD MESENCHYME
ECTODERM
SOMATIC MESODERM
EXTRA-
EMBRYOF
SOMATO
COELOM
-
PLEURE
DEVELOPING
ANTERIOR
CARDINAL
OPTIC VESICLE
VEIN
-
OPTIC STALK
SPLANCHNIC
SPLANCHNO PLEURE
ENDODERM
SUBCEPHALIC POCKET
PROAMNION
Drawing of specimen 45
NEUROCOELOR
NEURAL CANAL
ENDODERM
NEURAL FOLDS MEETING
NEURAL CREST
NEURAL TUBE- MID BRAIN REGION
HEAD FOLD OF AMNION
HEAD MESENCHYME
SOMATOPLEURE
NOTOCHORD
SOMATIC
PHARYNX
MESODERM
ECTODERM
HEAD FREE FROM
THE REST OF THE
HEAD ATTACHED
TO REST OF
BLASTODERM
BLASTODERM
(embryo asymmetrical
ENDODERM
or section
slightly obligue)
SPLANCHNIC
MESODERM
SUBCEPHALIC
POCKET
45
S
,
AMNIO-CARDIAC
VESICLE COELOM
45
46-Sj£-46
PROAMNION
47=41*47
SPLANCHNO PLEURE
Drawing of specimen 46
E
47.
Chick: 10-somite
stage, heart region, T.S.
mag. I50x
48.
Chick: 13-somite
stage, heart region, T.S.
mag. I50x
47, 48
—
ARTEFACT - NEURAL
FOLDS DO MEET
HIND BRAIN
NEUROCOEL
— SOMATOPLEURE
SOMATIC MESODERM
HEAD MESENCHYME
ECTODERM
NOTOCHORD
DORSAL AORTA
-
ENDOCARDIAL
SEPTUM
PHARYNX
ENDOCARDIUM
PERICARDIAL COELOM
—
EPI-
MYOCARDIUM
REMAINS OF
VENTRAL MESOCARDIUM
SPLANCHNOPLEURE
45
46
SPLANCHNIC
MESODERM
c
47|J
YOLK SAC ENDODERM
Drawing of specimen 47
ANTERIOR CARDINAL VEIN
CAVITY OF HIND BRAIN
DORSAL AORTA
RHOMBENCEPHALON
OR HIND BRAIN
HEAD MESENCHYME
AUDITORY PLACODE
AMMIOTIC
NOTOCHORD
FOLD
PHARYNX
—
SOMATO-
ECTODERM
DORSAL MESOCARDIUM
SOMATIC
ENDOTHELIUM
EPI-
MYOCARDIUM
HEART DISPLACED TO THE RIGHT
CAVITY OF HEART
(it is
on the left of slide
CONTAINING
because anterior surface
BLOOD CORPUSCLES
of section is
PERICARDIAL
ENDODERM
COELOM
SPLANCHNIC
MESODERM
SPLANCHNOPLEURE
Drawing of specimen 48
uppermost
45
-46
f47
49.
Chick:
50.
13 -somite stage,
Chick: 17-somite
posterior trunk region, T.S. mag.
stage,
trunk region, T.S. mag. I50x
/75x
49, 50
INTERMEDIATE MESODERM
OR NEPHROTOME
CENTRAL
PRIMORDIUM OF
CELLS
f
PRONEPHRIC TUBULE
NEURAL
ECTODERM
TUBE
SOMATIC MESODERM
ARTEFACT
S0MAT0PLEURE
SPLANCHNOPLEURE
SPLANCHNIC
MESODERM
ENDODERM
COELOM
DORSAL AORTA
Drawing of specimen 49
5TH SOMITE BEGINNING
TO DIFFERENTIATE
DERMATOME
LATERAL
MYOTOME
BOOY FOLD
POSTERIOR
CARDINAL VEIN
VITELLINE
VEIN
ECTODERM
AMNI0T1C
SOMATIC
FOLD
MESODERM
SOMATOPLEURE
—
'
EXTRA
EMBRYONIC
COELOM
SPLANCHNOPLEURE
VITELLINE
VEIN
504A
L SPLANCHNIC MESODERM
ENDODERM
Drawing of specimen 50
200x
mag.
T.S.
region,
trunk
stage,
21-somite
Chick:
51.
—1
cd
o
lU
a
o
t/o
2
*<
:
§
LU
51
ad
LU
Q
O
2
O O
o'
IZ
51
c_>
h<t
O 2
X
C O
0
:
LO
MESODERM
SPLANCHNIC
c
a»
E
‘u
o
a.
O
oo
c
>
cj
53.
Chick: 24-somite
stage, fore- and hind-brain, T.S. (2).
mag.
7
Ox
52, 53
LENS RUDIMENT CONSTRICTING
TO FORM A VESICLE
INFUNDIBULUM
OPTIC CUP
DEVELOPING
CHORION OR SEROSA
ARCH
1ST AORTIC
AMNION
NOTOCHORD
AMNIOTIC
MESENCHYME
METENCEPHALON
SOMATIC
ECTODERM
MESODERM
ECTODERM
SOMATIC
EXTRAEMBRYONIC
COELOM
MESODERM
SPLANCHNIC
MESODERM
YOLK SAC
ENDODERM
DIENCEPHALON
BRANCHES OF VITELLINE
VEIN
Drawing of specimen 52
ANTERIOR
1ST VISCERAL
CARDINAL VEIN
MYELENCEPHALON
SOMATIC
MESODERM
DORSAL
AORTA
,
\
<PHARYNQEAL>
POUCH
AUDITORY VESICLE -
PHARYNX
MOUTH OF VESICLE
1ST
AORTIC
CLOSING
DIENCEPHALON
AMNIOTIC CAVITY
ECTODERM
EXTRA
EMBRYONIC COELOM
CHORION
YOLKSAC-^
SPLANCHNIC
MESODERM
ENDODERM
PRE ORAL GUT
VITELLINE VEIN
TRIBUTARIES
NOTOCHORD
Drawing of specimen 53
ANTERIOR
CARDINAL VEIN
55.
Chick: 27-somite
stage, posterior
trunk region,
T.S.
mag.
95x
54, 55
MIGRATING NEURAL
~
CREST MATERIAL
NEURALTUBE
DERMATOME
SOMITE 18 IN EARLY STAGE
OF DIFFERENTIATION
AMNIOTIC
FOLD
NEURAL CREST
POSTERIOR CARDINAL VEIN
SCLEROTOME
MVOCOEL
'
LATERAL
BODY FOLD
.(SULCUS)
ECTODERM
SOMATIC
MESODERM
SPLANCHNIC“
MESODERM
f
.
ENDODERM
-
NOTOCHORD
MESONEPHRIC OR
WOLFFIAN DUCT
DORSAL AORTA
MESONEPHRIC TUBULE
Drawing of specimen 55
EXTRAEMBRYONIC
COELOM
90x
mag.
T.S.
region,
ear
and
eye
stage,
27-somite
Chick:
56.
56
75x
mag.
T.S.
hind-brain,
and
fore-
stage,
30-somite
Chick:
57.
f
57
specimen
of
Drawing
I30x
mag.
T.S.
region,
heart
stage,
30-somite
Chick:
58.
AORTAE
DORSAL
FUSED
r—
1
COELOM
•
OUT
EXTRA-EMBRYONIC
ROUND
MESODERM
SPLANCHNIC
*,-**
v*
59.
Chick: 30-somite
stage, anterior
trunk region,
T.S.
mag. I25x
59, 60
SERO-AMNIOTIC CONNECTION-
SEROSA OR CHORION
SECONDARY FOLD
AMNION
SOMITE
10
SOMITE 9
NEURAL TUBE
ECTODERM
SOMATIC
MESODERM
SPLANCHNIC
MESODERM
ENDODERM
—
YOLK SAC
VITELLINE VEIN
DERMATOME
MID OUT
MYOTOME
ANTERIOR INTESTINAL PORTAL
EXTRA-EMBRYONIC COELOM
— NOTOCHORD
SPLANCHNIC MESODERM
ROUND OUT
SCLEROTOME
EMBRYONIC COELOM
POSTERIOR
CARDINAL VEIN
DORSAL AORTA
Drawing of specimen 59
•SCLEROTOME
AM IN OTIC FOLD
NEURAL TUBE
AMNION
NEURAL CREST
CHORION
SOMITE
1
19
NEURAL CREST CELLS
MIGRATING TOWARDS
SCLEROTOME
or 20
MYOTOME
DERMATOME
AMNIOTIC CAVITY
MYOCOEL
ECTODERM
SOMATIC
YOLK SAC
MESODERM
SPLANCHNIC
MESODERM'
EXTRA
EMBRYONIC
COELOM
ENDODERM
NOTOCHORD
EMBRYONIC COELOM
POSTERIOR CARDINAL VEIN
DORSAL AORTA
VITELLINE VEIN
Drawing
of specimen 60
MESONEPHRIC DUCT
MESONEPHRIC TUBULE
9
62
62
specimen
of
Drawing
VEIN
ANTERIOR
CARDINAL
CHORION
OF
VENTRICLE
ECTODERM
I
-*V.
64
TELENCEPHALON
VEIN
CARDINAL
POSTERIOR
65.
66.
Chick: 36-somite
Chick: 45-somite
stage,
stage, tail
trunk region, T.S. mag. 75x
and hind-limb region, T.S. mag.
60x
65, 66
SEROSA OR CHORION
AMNIOTIC FOLD
AMNION
SERO- AMNIOTIC
AM Nl OTIC
CONNECTION
CAVITY
ECTODERM
NEURALTUBE
SOMATIC MESODERM
SOMITE 22
POSTERIOR CARDINAL
VEIN
MESONEPHRIC DUCT
DERMATOME
MYOTOME
MESONEPHRIC TUBULE
-
SPLANCHNIC
MESODERM
SCLEROTOME
ENDODERM
EXTRA- EMBRYONIC
COELOM
YOLK SAC
NOTOCHORD
LATERAL BODY FOLD
VITELLINE VEIN
DORSAL AORTA
—
5PLANCHN0C0EL
VITELLINE ARTERY
Drawing of specimen 65
SCLEROTOME
MYOTOME
NOTOCHORD
CHORION
ECTODERM OF CHORION
YOLK SAC
ECTODERM OF AMNION
ECTODERM OF EMBRYO
DORSAL AORTA
SPLANCHNIC
MESODERM
OF YOLK SAC
EXTRAEMBRYONIC
COELOM
ENDODERM
OF YOLK SAC
SOMATIC
MESODERM
AMNION
HIND
LIMB
AMNIOTIC
CAVITY
BUB
\
APICAL
RIDGE
POSTERIOR
CARDINAL VEIN
WOLFFIAN DUCT
RECTUM
CLOACA
ALLANTOIC STALK
AMNIOTIC CAVITY
Drawing of specimen 66
SPLANCHNOCOEL
67.
Chick:
36-somite stage,
H.L.S.
mag.
25x
ISTHMUS
METEMCEPHALON
NEUROMERES
MYELENCEPHALON
SEESSEL'5 POCKET
AMNIOTIC CAVITY
MESENCEPHALON
PHARYNX
TRUNCUS
ARTERIOSUS
OESOPHAGUS
INFUNDIBULUM
WALL OF
NEURAL TUBE
RATHKE'S POCKET
OR POUCH
DIENCEPHALON
TRACHEA
AURICLE
DORSAL AORTA
LIVER BUD
TELENCEPHALON
SINUS VENOSUS
VENTRICLE
NOTOCHORD
DERMATOMES
YOLK SAC
AMNION
SOMITES
SPINAL GANGLIA
VITELLINE VEIN
VITELLINE ARTERY
VITELLINE VEIN
MESONEPHRIC DUCT
DORSAL AORTA
AM Nl OTIC CAVITY
EXTRA- EMBRYONIC COELOM
AMNION
HIND LIMB BUD
RECTUM
SOMITE 35
NOTOCHORD
NEURAL TUBE
Drawing
of specimen 67
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CHANGE OF ADDRESS PROMPTLY
REFERENCE TABLE OF
A
Number
0
Anterior
Incu nation tinne in hov rs
accordin to:—
Lillie
P uettner Patten
Stage*
of
Mesoderm, somites
and kidney
Nervous system
Primitive streak
Duval
somites
17-18
20
4
18-19
18
Maximal length, 2.2
mm., i.e., 0.7 of area
Shield
and node present.
0
19
21
5
20
19-22
6
Begins to decrease
mm. Noto-
length, 1.9
portal
of
tive streak.
in
Neural plate and neural
Lateral horns of mesoderm
Mesenchyme
folds visible.
grow forward.
blood
The
first
somite may appear simultaneously with the formation of the head fold ( stage
chord grows forward
from node.
6
sheet
mesoderm
spreads
out
laterally from the primi-
Groove, pit
pellucida.
shaped
intestinal
Vascular system
islands
cells
in
form
isolated
extra-embryonic
mesoderm.
First
seen
to be present.
7).
3
8-
22
23
23
25-28
Reduced
1.5
to
a length of
mm.
Neural folds meet in brain
region but do not fuse.
Lateral horns grow round
the
mesodermless proam-
nion. Segmented somites
joined to lateral plate mesointermediate
derm
by
mesoderm
The blood islands begin to unite and
Moves back
the first blood corpuscles are pro-
as the foregut elon-
duced within the resulting
tubes.
gates.
nephrotome ).
A cavity, the myocoel, appears in somites.
5
8+
23-25
25
25-26
27-30
1.2
mm.
long.
Fusion of folds begins in
brain region; further back
neural folds meet but they
splay out over the somites.
(
The cells of the somites
become radially arranged
about the myocoel cavities;
cavity reduced by a central
core of cells. Lateral horns
The embryo becomes linked
to the
Lies poster-
blood island system by vitelline veins.
Paired primordia of the heart develop
heart prim-
together
aortae.
with
and dorsal
ventral
ior
the
to
ordia.
meet anteriorly.
10
13
29-30
10
33-34
11
30
33
30-31
33-34
33-38
40-45
0.6
0.4
mm.
mm.
long.
long.
Except for anterior neuropore, fusion offolds is completed in the brain region.
Three primary brain vesi-
The intermediate meso- The heart primordia fuse to form a
derm begins to separate off tubular heart which bends slightly to
dorsally. The pronephric
the right of the embryo. Faint and
tubules develop from this sporadic pulsation of the heart occurs.
cles visible.
material between somites
six and ten. The first somite
begins to disappear.
Five brain vesicles can be
seen. Anterior neuropore
closes. The neural folds fuse
beyond
thirteenth
the
somite.
17
12 +
37-41
37
38-40
46-50
0.2
mm.
long.
Fore brain at an angle to
hindbrain due to flexure. A
is
shallow infundibulum
present.
The dorso-lateral buds differentiate into pronephric
tubules and the pronephric
duct forms by fusion of
material from the tubules.
First signs of Wolffian duct.
43-46
43
44-48
48-52
No longer distinguishable: contributes material to tail
bud.
Fore brain at right angles
to hind brain. Fore brain
enlarges
in
telencephalon
The heart
stage
heart is S-shaped. The first aortic
arch begins to develop. The dorsal
aortae J'use between somites three
and four. The vitelline artery can be
seen between somites sixteen and
seventeen.
ites
and
is lost.
Pronephros begins to
appear anterior to
dis-
the
eleventh somite. In the anterior somites a distinct der-
region.
matome can be seen and
cells
migrate from the
somites and neural crests to
form the sclerotomes round
the notochord.
24
44-16
15
48
48-50
50-55
The telencephalon becomes
distinct
from
the
dien-
cephalon. Rathke's pocket
grows under the infundibulum.
27
48
16
30
52
17
36
18
+
68-72
50-52
58-60
72
50-55
55-60
72
51-56
52-64
72
Telencephalon and diencephalon become separated
by the velum transversum.
A distinct isthmus can be
seen between the mesencephalon
and metencephalon.
The
isthmus
deepens.
Paired telencephalic vesicles
develop. Roof of hind brain
becomes very thin in myelencephalon region. Brain
bent double by now.
The cerebral hemispheres
develop from the telencephalic vesicles.
The inwith
fundibulum
joins
Rathke's pocket to form
the pituitary.
•
Hamilton
& Hamburger
beating efficiently by
Connection between som-
duct extends from tenth to
fifteenth somite. Differentiation begins in anterior
somites.
14 +
distinctly dis-
nephrotomes
The mesonephros develops
pronephros
along
with
below the somites. Wolffian
21
The heart becomes
placed to the right. The rate and amplitude of the heart beats increase. A
network of blood vessels established
in area vasculosa.
The posterior somites remain undifferentiated ; anteriorly
somites
tiate into
dermatome, myo-
differen-
tome and sclerotome. There
are eleven pairs of mesonephric tubules between
somite five and sixteen.
into
der-
myotome
and
Differentiation
matome,
sclerotome reaches somite
twenty. Wolffian duct and
mesonephric tubules seen in
trunk sections.
is
and blood
this
circulates.
The
The atrium begins to divide into right
and left auricles. The first aortic arch
is established and the second begins
May reach
the
first
somite.
Reaches the
second
somite.
Reaches the
third
somite.
Reaches the
fourth
somite.
to form. Fusion of dorsal aortae may
reach somite eight. The vitelline
artery is distinct between somites
17-19.
Besides the two auricles heart has
Is
distinct ventricle and conus arteriosus. Two aortic arches present.
region
of
somites five
Dorsal aortae fuse as far back as
somite twelve. The vitelline arteries
lie between somites eighteen and
twenty.
to six.
appears. The
The third aortic
arch
dorsal aortae fuse between somites
four and fourteen. The vitelline
artery lies between somites 19 and
21.
Vitelline
ductus
veins
venosus
join
which
to
opens
the
in
Lies
be-
tween somites
and
seven
ten.
form
into
sinus venosus.
Differentiation reaches the
twenty-fifth somite. Wolffian duct grows back towards cloaca. Glomeruli
can be seen
in
mesonephric
tubules.
Differentiation reaches the
somite. Wolffian
reaches cloaca but
not fuse with it until
thirtieth
duct
may
later.
There are three complete aortic
arches and the fourth begins to
develop.
The
first
pair
of aortic
may begin to atrophy at this
Dorsal aortae fused up to
somite 16. Vitelline artery between
somites 20 and 22.
Has moved
back to
between
lie
arches
somites ten
stage.
and
twelve.
The
first pair of aortic arches continue to atrophy as the fourth pair
develop. Dorsal aortae fused as far
Between
back as somites 17-20. Vitelline
artery is in region of somites 21-22.
fourteen.
somites
thirteen
and
CHICK DEVELOPMENT
Eyes
Alimentary system
Ami
Torsion
Flexure
Ears
bud
and
Tail
-
1
Allantois
limb buds
1
L
Foregut 0.15
mm.
long.
1
Foregut 0.3 to 0.4
mm.
long.
Foregut 0.5 to 0.8
mm.
long.
Foregut about 1.0
mm.
long.
Foregut
about 1.3 mm. long.
is
Primary
form.
optic
vesicles
The head bends ventrally
and sinks into the yolk.
stalks begin to
constrict at the base of
the primary vesicles.
Optic
The auditory placodes begin to form
thickened
ectoderm.
This cranial flexure increases in the region of the
mid-brain.
The
The ectoderm outside the
primary vesicles thickens
The
Further sinking of the head
into the yolk is prevented by
The head turns on
and becomes the
ment of the lens.
form auditory
Differentiated into optic
and optic vesicle.
stalk
from
The foregut is 1.5 mm. long
there are indications of
the first pair of visceral clefts.
and
The first pair of visceral clefts
are distinct and the second
pair begin to form.
The
first
and second
visceral
clefts are clearly visible; the
The
lens
rudi-
rudiments
in-
vaginate to form lens
vesicles. The optic vesicles invaginate to form
optic cups
auditory placodes invaginate to
pits.
The mouth of each
auditory pit begins
to
constrict
and
vesicles
auditory
form.
The mouth of the lens
The mouth of the
vesicle begins to close.
auditory
vesicle
is
third pair begin to develop.
reduced to a small
The hind gut appears.
aperture.
first signs of
torsion appear in the
head region.
to
Cranial flexure approaches
the left side. This
torsion may reach
the first two or three
90°.
somites.
the
head twisting
(torsion).
Cranial flexure, i.e. angle
between fore- and hindbrain, is 90°. Cervical flexure begins in hind-brain
region and trunkflexure can
also be seen.
Cranial flexure causes the
fore-brain to be directed
backwards close to the
Cervical flexure
heart.
The head
is
fully
turned to the left.
The first five to seven
somites also exhibit
is
apparent
in somites eight to
ten.
becomes a broad curve.
The
second and third
first,
visceral
The
clefts
liver
are present.
bud appears as do
and anal plate.
the tail gut
The fourth pair of visceral
clefts develop. The liver bulge
is
now
extends
conspicuous. Tail gut
further into tail.
Cloaca begins
Cranial flexure
to the
maximum. Cervical flexure
somites
increases. Trunk flexure is
noticeable in the region of
somites ten to twelve.
twelve and thirteen
or even further.
optic
cups are almost
dosed. The retina distinct. The eye is still anterior to the ear.
ticus.
The optic cup
eyes
now
lie
closes.
The
The aperture
closes.
posterior to
the ears.
to form.
Four pairs of visceral clefts.
The tail gut begins to degenerate. The anterior and posterior
intestinal portals approach
each other, leaving an open
intestinal umbilicus of 3 mm.
Lung buds develop.
The eyes, due to flexure,
well posterior to the
ears.
lie
Torsion extends to
vesicle
small
ectodermal
the
aperture
by
ductus endolympha-
The lens becomes cut off The auditory
from the ectoderm. The is connected
The auditory vesicle
is pear-shaped with
a narrow ductus endolymphaticus.
is
at
its
Cranial flexure remains unchanged. Cervicalflexure is
about 100°. Trunk flexure
develops into a broad curve.
Caudal flexure begins.
The remains of the
primitive
streak
begin contributing
material posteriorly
to the tail bud.
The head amniotic fold
has grown back over
the fore-brain.
There
The hind brain andfirst
few somites are cov-
tail
is
a
distinct
bud.
ered by the amnion.
Tailfolds may begin to
develop.
torsion.
Torsion
The head amniotic fold
begins to rise up and
grow back.
eleven,
The
The sero-amniotic connection is somewhat
attenuated. The amnion covers somites six
to thirteen. Tail fold
appears.
The
The head fold grows
back and nay lie anywhere betv een somites
ten and
ghteen. The
fold has ex- Hfcg/m' as an
of
tended to the region r outgrowth
between omitcs six- the hind gut in
teen
to
weiuy-four.
Caudal flexure causes tail
to be at an angle of 90° to
The whole posterior
region exhibits some
the body.
degree of torsion.
the cloacal region.
The head nd tad folds Allantoic stalk
vesicle.
meet or ave v small and
over WThe vesicle enoval ap rture
larges after 72
Z
tail
bud can be
ings.
The head
The tailfo d has grown
forward over somites 29-30
bud begins
seen projecting behind the hind gut.
The
limb
buds
appear as low swell-
tailfold be gins to grow
forward.
Torsion as far back
as somites fifteen to
nineteen.
tail
to develop posterior
to the hind gut.
tuiours.
The
bud begins
Limb buds are now
quite
conspicuous
and begin to exhibit
nipple-shaped apices
The hind limb bud
extends to somite
32.
I
tail
curve forward.
The fore limb bud
lies between somites
17-19 and the hind
limb bud between
somites 26-30.
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