Week 6

Embryology - 19 Apr 2024 Expand to Translate
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Key Events of Human Development during the sixth week (week 6) following fertilization or clinical gestational age GA week 8 (LMP).

This week corresponds to Carnegie stages 16 and 17.

Carnegie Collection Embryos - Stage 16
Serial No.	Size (mm)	Grade	Fixative	Embedding Medium	Plane	Thinness (µm)	Stain	Year	Notes
163	E., 9.0 Ch., 35x35x20	Good	Formol	P	Transverse	20	Al. coch.	1899	Used by Bardeen and Lewis
221	E., 7.5 Ch., 40x33x33	Poor	Formalin	P	Sagittal	20	Al. coch.	1903	Macerated
383	E., 7.0 Ch., 15x15x15	Poor	Formalin	P	Transverse	10	Al. carm., H. & Congo red	1904
397	E., 8.0 Ch., 15x15x15	Poor	Formalin	P	Transverse	10	(Stain - Haematoxylin Eosin)	1907
422	E., 9.0 Ch., 30x30x30	Poor	Alc.	P	Transverse	40	Al. coch.	1910	Tubal. Partly macerated
559	E., 8.6 Ch., 20x15x12	Good	Formalin	P	Transverse	20	H. & Congo red	1911	Cyclopia. Formerly listed as stage 17
589	E., 11 Ch., 30x13x13	Poor	p	P	Sagittal	50	Al. coch.	1912
617	E., 7.0 Ch., 18x14x12	Good	Formalin	P	Transverse	15	Al. coch.	1912	Median in group
636	E., 10 Ch.,28x28x22	Poor	Formalin	P	Transverse	50	Al. coch.	1913	Macerated
651f	E., 7 Ch., 25x20x15	Poor	p	p	p	p	p	1913	Spina bifida
675	E., 10 Ch., 50x30x25	Poor	Formalin	P	Sagittal	100	Carmine	1915	Abnormal head and limbs
792	E., 8.0 Ch., 40x30x30	Good	Formalin	P	Transverse	20	Al. coch.	1913	Advanced
887	E, 9.0 Ch., 31x28x17	Good	Formalin	P	Transverse	40	Al. coch.	1914	Near next stage
1121	E., 11.8	Good	Corros. acetic	P	Coronal	40	Al. coch.	1915	Operative. Median in group
1197	E., 10.0 Ch., 23x19x15	Good	Formalin	C	Sagittal	20	(Stain - Haematoxylin Eosin), or. G.	1915	Advanced
1544	E., 7.2	Good	Zenker	P	Sagittal	20	Al. coch.	1916	Tubal. Mechanical injury
1836	E., 11.0	Good	Formalin	P	Transverse	20	(Stain - Haematoxylin Eosin)	1917	Most-advanced third
4677	E., 9.5 Ch., 48x36x30	Good	Formalin	P	Transverse	10	Al. coch.	1924	Median in group
5515	E., 12.0 Ch., 47x37x25	Good	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1927	Near next stage
6054	E., 7,0 Ch., 21x17x12	Good	Formalin	C-P	Transverse	8	(Stain - Haematoxylin Eosin)	1930	Least-advanced third
6507	E., 9.0*	Excellent	Corros. acetic	C-P	Coronal	10 & 8	Al. coch.	p	Middle or most-advanced third
6509	E. 8.1*	Excellent	Corros. acetic	C-P	Coronal	10	Al. coch.	p	Least-adianced or middle third
6510	E., 10.1*	Excellent	Corros. acetic	C-P	Coronal	10	Al. coch.	p	Close to No. 6507. Ag added
6511	E, 8.1*	Good	Corros. acetic	C-P	Sagittal	10	Al. coch., iron H.	p	Surface injured by fixative. Most-advanced third
6512	E., 7.0*	Excellent	Corros. acetic	C-P	Transverse	10	Al. coch.	p	Least-advanced third. Borderline
6513	E., 7.2*	Good	Corros. acetic	C-P	Coronal	10	Al. coch.	p	Surface injured by fixative. Least advanced in group
6514	E, 9 0*	Poor	Corros. acetic	C-P	Sagittal	10	Al. coch.	p	Most-advanced third
6516	E., 10 5*	Good	Corros acetic	C-P	Sagittal	8	Al. coch.	p	Most-advanced third. Double left kidney and ureter
6517	E., 10.5*	Excellent	Corros. acetic	C-P	Transverse	8	Al. coch.	?	Close to No. 6516
6686	E., 11.0 Ch., l7x17xP	Poor	Formalin	C-P	Coronal	20	Al. coch.	1933	Tubal. Partly macerated
6750	E., 10.0	Good	Formalin	C-P	Transverse	10	H. & phlox.	1933	Tubal. Advanced
6909	E., 11.0	Good	Bouin	C-P	Coronal	10	(Stain - Haematoxylin Eosin)	1934	Tubal. Advanced
6931	E., 8.8 Ch., 3""x 33x16	Good	Formalin	C-P	Coronal	10	Al coch., phlox.	1934	Least-advanced third. Type specimen
6950	E.. 9 0 Ch., 3lx20x18	Good	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1934	Tubal. Partly fragmented
7?15	E., 9.7	Exc	Bouin	C-P	Coronal	10	H. & phlox	1935	Operative. Less advanced
7629	E., 11.5 Ch., 31x31	Good	Formalin	C-P	Coronal	10	Al. coch., phlox	1939	Hysterectomy. Most advanced in group
7804	E., 9.5 Ch., 26x21x16	Good	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1940	Least-advanced third
7897	E., 12.2 Ch., 31x24x23	Good	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1941	Tubal. Advanced
8098	E., 10.0 Ch., 30	Good	Formalin	C-P	Coronal	6	(Stain - Haematoxylin Eosin)	1942	Tubal. Median in group
8112	E., 10.9	Excellent	Bouin	C-P	Coronal	8	(Stain - Haematoxylin Eosin)	1943	Most-advanced third
8179	E., 11.9 Ch., 23x18x17	Good	Formalin	C-P	Coronal	10	(Stain - Haematoxylin Eosin)	1943	Tubal
8436	E., 10.9 Ch., 13x15x1?	Good	Formalin	P	Coronal	10	Azan	1946	Advanced
8692	E., 10	Good	Bouin	P	Transverse	10	(Stain - Haematoxylin Eosin)	1949	Rubella. Medical abortion. Mechanically damaged
8697	E., 11.3	Poor	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1949	Perhaps stage 17
8773	E, 11	Excellent	Bouin	P	Coronal	10	Azan	1950
8971	E., 10 Ch., 20.5x14.5x13.7	Poor	Formalin		Transverse	15	(Stain - Haematoxylin Eosin)	1932	Synophthalmia. Univ. Chicago No. H 1439
Template:CE9055	E., ca. 10	Excellent	Bouin	P	Transverse	20	Azan & Ag	1953	Damaged
9229	E, 9.5	Excellent	Formalin	P	Transverse	6	Ag & (Stain - Haematoxylin Eosin)	1954	Stage 15, 16, or 17? Mislaid
Abbreviations Size - E. is the greatest length of the embryo and Ch. is the mean diameter of the chorion. Grade - total grade of the specimen and includes both its original quality and the condition of the mounted sections. Embedding medium - paraffin (P) or a combination of celloidin and paraffin (C-P). Fixative - formalin (Formol), alcohol and formalin (Alc, formol), Bouin Bouin solution) Stain - ? - unknown or not determined.

Carnegie Collection Embryos - Stage 17
Serial No.	Size (mm)	Grade	Fixative	Embedding Medium	Plane	Thinness (µm)	Stain	Year	Notes
353	E, 11.0 Ch., 40x35x20	Good	Formalin	P	Coronal	10	(Stain - Haematoxylin Eosin)	1906	Very advanced
485	E, 13.0 Ch., 33x25	Exc.	Formalin	P	Coronal	40	Al. coch.	1911	Injected (India ink)
544	E., 11.5 Ch., 30	Good	Zenker-Formol	P	Sagittal	40	Al. coch.	1911	Operative Injected (India ink)
562	E, 13.0 Ch., 28x17x17	Poor	Formalin	P	Sagittal	100	Al. coch.	1912	Advanced
623	E 10.1	Good	Alc.	P	Transverse	20	H. & Congo red	1912	Operative. Median in group
695	E, 13.5 Ch., 40x40x17	Poor	Formalin	P	Transverse	10	H. & Congo red	1913	Macerated
916	E, 11.0 Ch, 30x30x16	Good	Bouin	C	Transverse	40	H.&E, or. G.	1915	Most-advanced third
940	E, 14.0 Ch, 28x23x21	Good	Formalin	C	Transverse	40	H.&E, or. G.	1914	Advanced
1232	E, 14.5 Ch., 35x35x30	Poor	Formalin	P	Coronal	40	Al. coch.	1915	Close to No.1267A
1267A	E-a 145 Ch., 35x30x26 40	Good	Formalin	C	Sagittal	20	(Stain - Haematoxylin Eosin). or. G	1915	Excellent CN.S.
1267B ??	E, 125	Good	Formalin	p	Sagittal	20	(Stain - Haematoxylin Eosin)	1917	Tubal
5642	E, 11.5 Ch.. 33x30x17	Good	Formalin	p	Transverse	15	Al. coch.	1928	Right upper limb injured
5893	E.. 13.2	Good	Formalin	C-P	Transverse	20	Al. coch.	1929	Most advanced in group
6258	E. 14.0 Ch 48x35x25	Good	Formalin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1930	Median in group
6519	E.. 10.8*	Exc	Corrov acetic	C-P	Sagittal	8	Al. coch.	?	Least-advanced or middle third
6520	E., 14.2*	Exc.	Corros. acetic	C-P	Transverse	10	Al. coch.	P	Median in group. Ag added to slides 1-25
6521	E., 13.2*	Exc.	Corros. acetic	C-P	Transverse	8-18	Al. coch.	?	Sections vary in thinness
6631	E., 13.0	Good	Formalin	C-P	Coronal	10	(Stain - Haematoxylin Eosin)	1932	Tubal. Advanced
6742	E, 11.0 Ch.,50x40x15	Good	Formalin	C-P	Transverse	12	H. & phlox.	1933	Good primary germ cells
6758	E., 12.8	Good	Formalin	C-P	Transverse	10	H. & phlox.	1933	Least—advanced third
7317	E, 10.0*	Good		P	Coronal	10	(Stain - Haematoxylin Eosin)	1936	His embryo “Ru." Every third section
7436	E., 13.0	Good	Formalin	C-P	Coronal	30	Al. coch.	1937	Most-advanced third
8101	E., 13.0	Exc.	Bouin	C-P	Transverse	10	(Stain - Haematoxylin Eosin)	1943	Operative
8118	E., 12.6	Exc.	Bouin	C-P	Coronal	10	(Stain - Haematoxylin Eosin)	1943	Middle third
8253	E., 11.2 Ch.,30x20x10	Good	Bouin	C-P	Coronal	10	Al. coch., phlox.	1944	Operative. Least advanced in group
8789	E., 11.7	Exc.	Bouin	C-P	Sagittal	10	Azan	1950
8969	E., 11.2	Exc.	?	p	Transverse	15	Azan	1919	Univ. Chicago No. H566
8998	E., 11.0	Exc.	?	C-P	Coronal	10	Azan	1952
9100	E., 12.0 Ch., 12x13x10	Exc.	Formol-chrom. subl.	C-P	Sagittal	10	Azan	1933	Univ. Chicago No. H1475
9282	E, 12.0 Ch., 16	Good	Ale.	p	Transverse	15	Ag	1955	Mislaid
Abbreviations Size - E. is the greatest length of the embryo and Ch. is the mean diameter of the chorion. Grade - total grade of the specimen and includes both its original quality and the condition of the mounted sections. Embedding medium - paraffin (P) or a combination of celloidin and paraffin (C-P). Fixative - formalin (Formol), alcohol and formalin (Alc, formol), Bouin (Bouin solution) Stain - ? - unknown or not determined.

Week:	1	2	3	4	5	6	7	8
Carnegie stage:	1 2 3 4	5 6	7 8 9	10 11 12 13	14 15	16 17	18 19	20 21 22 23

Timeline

Week 6 - Human Embryo Stages and Events (GA week 8)
Embryo Week: Week 1 \| Week 2 \| Week 3 \| Week 4 \| Week 5 \| Week 6 \| Week 7 \| Week 8 \| Week 9
Day	Stage	Event
36		Pituitary - Week 6 connecting stalk between pouch and oral cavity degenerates Parathyroid - Week 6 diverticulum elongate, hollow then solid, dorsal cell proliferation Thymus - Week 6 diverticulum elongate, hollow then solid, ventral cell proliferation Adrenal - Week 6 fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia Respire - Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes Tongue Week 6 - gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium)
37	Stage 16	Neural - first parasympathetic ganglia, submandibular and ciliary, are identifiable^[1] Limbs upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis. Heart - outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears.
38
39
40
41	Stage 17	Neural - telencephalon areas of the future archicortex, paleocortex, and neocortex, visible. Beginning of future choroid plexus^[2] Sense - Smell olfactory nerve fibres enter the brain^[3] Neural - primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally^[4] Pancreas - rotation of the developing stomach moves ventral bud dorsally and fuses with the dorsal bud.
42		Heart - separation of common cardiac outflow (aortic arch and pulmonary aorta)
Note - the day timing of stages is only approximate, system names link to first page of that specific system, and events are based upon the literature cited below.
References ↑ <pubmed>2751117</pubmed> ↑ <pubmed>2802187</pubmed> ↑ <pubmed>15604533</pubmed> ↑ <pubmed>15478101</pubmed>

Day	Stage	Event
36		Pituitary - Week 6 connecting stalk between pouch and oral cavity degenerates Parathyroid - Week 6 diverticulum elongate, hollow then solid, dorsal cell proliferation Thymus - Week 6 diverticulum elongate, hollow then solid, ventral cell proliferation Adrenal - Week 6 fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia Respire - Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes Tongue Week 6 - gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium)
37	Stage 16	Neural - first parasympathetic ganglia, submandibular and ciliary, are identifiable^[1] Limbs upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis. Heart - outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears.
38
39
40
41	Stage 17	Neural - telencephalon areas of the future archicortex, paleocortex, and neocortex, visible. Beginning of future choroid plexus^[2] Sense - Smell olfactory nerve fibres enter the brain^[3] Neural - primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally^[4] Pancreas - rotation of the developing stomach moves ventral bud dorsally and fuses with the dorsal bud.
42		Heart - separation of common cardiac outflow (aortic arch and pulmonary aorta)

References

↑ <pubmed>2751117</pubmed>
↑ <pubmed>2802187</pubmed>
↑ <pubmed>15604533</pubmed>
↑ <pubmed>15478101</pubmed>

Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 19) Embryology Week 6. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Week_6

What Links Here?

[1] <pubmed>2751117</pubmed>

[2] <pubmed>2802187</pubmed>

[3] <pubmed>15604533</pubmed>

[4] <pubmed>15478101</pubmed>

[5] <pubmed>2751117</pubmed>

[6] <pubmed>2802187</pubmed>

[7] <pubmed>15604533</pubmed>

[8] <pubmed>15478101</pubmed>

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