Talk:Carnegie stage 22 - serial sections

From Embryology

Labeled Image Description Table

Stage 22 (serial labeled images)
Section Name Description
Stage 22 image 050.jpg A1L Description
Stage 22 image 051.jpg A2L Description
Stage 22 image 052.jpg A3L Description
Stage 22 image 053.jpg A4L Description
Stage 22 image 054.jpg A5L Description
Stage 22 image 055.jpg A6L Description
Stage 22 image 056.jpg A7L Description
Stage 22 image 057.jpg B1L Description
Stage 22 image 058.jpg B2L Description
Stage 22 image 059.jpg B3L Description
Stage 22 image 060.jpg B4L Description
Stage 22 image 061.jpg B5L Description
Stage 22 image 062.jpg B6L Description
Stage 22 image 063.jpg B7L Description
Stage 22 image 064.jpg C1L Description
Stage 22 image 065.jpg C2L Description
Stage 22 image 066.jpg C3L Description
Stage 22 image 067.jpg C4L Description
Stage 22 image 068.jpg C5L Description
Stage 22 image 069.jpg C6L Description
Stage 22 image 070.jpg C7L Description
Stage 22 image 071.jpg D1L Description
Stage 22 image 072.jpg D2L Description
Stage 22 image 073.jpg D3L Description
Stage 22 image 074.jpg D4L Description
Stage 22 image 075.jpg D5L Description
Stage 22 image 076.jpg D6L Description
Stage 22 image 077.jpg D7L Description
Stage 22 image 078.jpg E1L Description
Stage 22 image 079.jpg E2L Description
Stage 22 image 080.jpg E3L Description
Stage 22 image 081.jpg E4L Description
Stage 22 image 082.jpg E5L Description
Stage 22 image 083.jpg E6L Description
Stage 22 image 084.jpg E7L Description
Stage 22 image 085.jpg F1L Description
Stage 22 image 086.jpg F2L Description
Stage 22 image 087.jpg F3L Description
Stage 22 image 088.jpg F4L Description
Stage 22 image 089.jpg F5L Description
Stage 22 image 090.jpg F6L Description
Stage 22 image 091.jpg F7L Description
Stage 22 image 092.jpg G1L Description
Stage 22 image 093.jpg G2L Description
Stage 22 image 094.jpg G3L Description
Stage 22 image 095.jpg G4L Description
Stage 22 image 096.jpg G5L Description
Stage 22 image 097.jpg G6L Description
Stage 22 image 098.jpg G7L Description


Stage 22 image 099.jpg

Unlabeled Image Files

Stage 22 image 001.jpg | Stage 22 image 002.jpg | Stage 22 image 003.jpg | Stage 22 image 004.jpg | Stage 22 image 005.jpg | Stage 22 image 006.jpg | Stage 22 image 007.jpg | Stage 22 image 008.jpg | Stage 22 image 009.jpg | Stage 22 image 010.jpg | Stage 22 image 011.jpg | Stage 22 image 012.jpg | Stage 22 image 013.jpg | Stage 22 image 014.jpg | Stage 22 image 015.jpg | Stage 22 image 016.jpg | Stage 22 image 017.jpg | Stage 22 image 018.jpg | Stage 22 image 019.jpg | Stage 22 image 020.jpg | Stage 22 image 021.jpg | Stage 22 image 022.jpg | Stage 22 image 023.jpg | Stage 22 image 024.jpg | Stage 22 image 025.jpg | Stage 22 image 026.jpg | Stage 22 image 027.jpg | Stage 22 image 028.jpg | Stage 22 image 029.jpg | Stage 22 image 030.jpg | Stage 22 image 031.jpg | Stage 22 image 032.jpg | Stage 22 image 033.jpg | Stage 22 image 034.jpg | Stage 22 image 035.jpg | Stage 22 image 036.jpg | Stage 22 image 037.jpg | Stage 22 image 038.jpg | Stage 22 image 039.jpg | Stage 22 image 040.jpg | Stage 22 image 041.jpg | Stage 22 image 042.jpg | Stage 22 image 043.jpg | Stage 22 image 044.jpg | Stage 22 image 045.jpg | Stage 22 image 046.jpg | Stage 22 image 047.jpg | Stage 22 image 048.jpg | Stage 22 image 049.jpg

Labeled Image Files

Stage 22 image 050.jpg | Stage 22 image 051.jpg | Stage 22 image 052.jpg | Stage 22 image 053.jpg | Stage 22 image 054.jpg | Stage 22 image 055.jpg | Stage 22 image 056.jpg | Stage 22 image 057.jpg | Stage 22 image 058.jpg | Stage 22 image 059.jpg | Stage 22 image 060.jpg | Stage 22 image 061.jpg | Stage 22 image 062.jpg | Stage 22 image 063.jpg | Stage 22 image 064.jpg | Stage 22 image 065.jpg | Stage 22 image 066.jpg | Stage 22 image 067.jpg | Stage 22 image 068.jpg | Stage 22 image 069.jpg | Stage 22 image 070.jpg | Stage 22 image 071.jpg | Stage 22 image 072.jpg | Stage 22 image 073.jpg | Stage 22 image 074.jpg | Stage 22 image 075.jpg | Stage 22 image 076.jpg | Stage 22 image 077.jpg | Stage 22 image 078.jpg | Stage 22 image 079.jpg | Stage 22 image 080.jpg | Stage 22 image 081.jpg | Stage 22 image 082.jpg | Stage 22 image 083.jpg | Stage 22 image 084.jpg | Stage 22 image 085.jpg | Stage 22 image 086.jpg | Stage 22 image 087.jpg | Stage 22 image 088.jpg | Stage 22 image 089.jpg | Stage 22 image 090.jpg | Stage 22 image 091.jpg | Stage 22 image 092.jpg | Stage 22 image 093.jpg | Stage 22 image 094.jpg | Stage 22 image 095.jpg | Stage 22 image 096.jpg | Stage 22 image 097.jpg | Stage 22 image 098.jpg


Icon Table 80px size

Stage 22 (serial unlabelled images)
Stage 22 image 001.jpg Stage 22 image 002.jpg Stage 22 image 003.jpg Stage 22 image 004.jpg Stage 22 image 005.jpg Stage 22 image 006.jpg Stage 22 image 007.jpg
Stage 22 image 008.jpg Stage 22 image 009.jpg Stage 22 image 010.jpg Stage 22 image 011.jpg Stage 22 image 012.jpg Stage 22 image 013.jpg Stage 22 image 014.jpg
Stage 22 image 015.jpg Stage 22 image 016.jpg Stage 22 image 017.jpg Stage 22 image 018.jpg Stage 22 image 019.jpg Stage 22 image 020.jpg Stage 22 image 021.jpg
Stage 22 image 022.jpg Stage 22 image 023.jpg Stage 22 image 024.jpg Stage 22 image 025.jpg Stage 22 image 026.jpg Stage 22 image 027.jpg Stage 22 image 028.jpg
Stage 22 image 029.jpg Stage 22 image 030.jpg Stage 22 image 031.jpg Stage 22 image 032.jpg Stage 22 image 033.jpg Stage 22 image 034.jpg Stage 22 image 035.jpg
Stage 22 image 036.jpg Stage 22 image 037.jpg Stage 22 image 038.jpg Stage 22 image 039.jpg Stage 22 image 040.jpg Stage 22 image 041.jpg Stage 22 image 042.jpg
Stage 22 image 043.jpg Stage 22 image 044.jpg Stage 22 image 045.jpg Stage 22 image 046.jpg Stage 22 image 047.jpg Stage 22 image 048.jpg Stage 22 image 049.jpg


Icon Table 100px size

Stage 22 (serial unlabelled images)
Stage 22 image 001.jpg Stage 22 image 002.jpg Stage 22 image 003.jpg Stage 22 image 004.jpg Stage 22 image 005.jpg Stage 22 image 006.jpg Stage 22 image 007.jpg
Stage 22 image 008.jpg Stage 22 image 009.jpg Stage 22 image 010.jpg Stage 22 image 011.jpg Stage 22 image 012.jpg Stage 22 image 013.jpg Stage 22 image 014.jpg
Stage 22 image 015.jpg Stage 22 image 016.jpg Stage 22 image 017.jpg Stage 22 image 018.jpg Stage 22 image 019.jpg Stage 22 image 020.jpg Stage 22 image 021.jpg
Stage 22 image 022.jpg Stage 22 image 023.jpg Stage 22 image 024.jpg Stage 22 image 025.jpg Stage 22 image 026.jpg Stage 22 image 027.jpg Stage 22 image 028.jpg
Stage 22 image 029.jpg Stage 22 image 030.jpg Stage 22 image 031.jpg Stage 22 image 032.jpg Stage 22 image 033.jpg Stage 22 image 034.jpg Stage 22 image 035.jpg
Stage 22 image 036.jpg Stage 22 image 037.jpg Stage 22 image 038.jpg Stage 22 image 039.jpg Stage 22 image 040.jpg Stage 22 image 041.jpg Stage 22 image 042.jpg
Stage 22 image 043.jpg Stage 22 image 044.jpg Stage 22 image 045.jpg Stage 22 image 046.jpg Stage 22 image 047.jpg Stage 22 image 048.jpg Stage 22 image 049.jpg


Icon Table 120px size

Stage 22 (serial unlabelled images)
Stage 22 image 001.jpg Stage 22 image 002.jpg Stage 22 image 003.jpg Stage 22 image 004.jpg Stage 22 image 005.jpg Stage 22 image 006.jpg Stage 22 image 007.jpg
Stage 22 image 008.jpg Stage 22 image 009.jpg Stage 22 image 010.jpg Stage 22 image 011.jpg Stage 22 image 012.jpg Stage 22 image 013.jpg Stage 22 image 014.jpg
Stage 22 image 015.jpg Stage 22 image 016.jpg Stage 22 image 017.jpg Stage 22 image 018.jpg Stage 22 image 019.jpg Stage 22 image 020.jpg Stage 22 image 021.jpg
Stage 22 image 022.jpg Stage 22 image 023.jpg Stage 22 image 024.jpg Stage 22 image 025.jpg Stage 22 image 026.jpg Stage 22 image 027.jpg Stage 22 image 028.jpg
Stage 22 image 029.jpg Stage 22 image 030.jpg Stage 22 image 031.jpg Stage 22 image 032.jpg Stage 22 image 033.jpg Stage 22 image 034.jpg Stage 22 image 035.jpg
Stage 22 image 036.jpg Stage 22 image 037.jpg Stage 22 image 038.jpg Stage 22 image 039.jpg Stage 22 image 040.jpg Stage 22 image 041.jpg Stage 22 image 042.jpg
Stage 22 image 043.jpg Stage 22 image 044.jpg Stage 22 image 045.jpg Stage 22 image 046.jpg Stage 22 image 047.jpg Stage 22 image 048.jpg Stage 22 image 049.jpg

Image Files

Unlabeled

Stage 22 image 01.jpg Stage 22 image 02.jpg Stage 22 image 03.jpg Stage 22 image 04.jpg Stage 22 image 05.jpg Stage 22 image 06.jpg Stage 22 image 07.jpg Stage 22 image 08.jpg Stage 22 image 09.jpg Stage 22 image 010.jpg Stage 22 image 011.jpg Stage 22 image 012.jpg Stage 22 image 013.jpg Stage 22 image 014.jpg Stage 22 image 015.jpg Stage 22 image 016.jpg Stage 22 image 017.jpg Stage 22 image 018.jpg Stage 22 image 019.jpg Stage 22 image 020.jpg Stage 22 image 021.jpg Stage 22 image 022.jpg Stage 22 image 023.jpg Stage 22 image 024.jpg Stage 22 image 025.jpg Stage 22 image 026.jpg Stage 22 image 027.jpg Stage 22 image 028.jpg Stage 22 image 029.jpg Stage 22 image 030.jpg Stage 22 image 031.jpg Stage 22 image 032.jpg Stage 22 image 033.jpg Stage 22 image 034.jpg Stage 22 image 035.jpg Stage 22 image 036.jpg Stage 22 image 037.jpg Stage 22 image 038.jpg Stage 22 image 039.jpg Stage 22 image 040.jpg Stage 22 image 041.jpg Stage 22 image 042.jpg Stage 22 image 043.jpg Stage 22 image 044.jpg Stage 22 image 045.jpg Stage 22 image 046.jpg Stage 22 image 047.jpg Stage 22 image 048.jpg Stage 22 image 049.jpg

Labeled

Stage 22 image 0aseries.jpg Stage 22 image 0RegisterA.jpg Stage 22 image 0Untitled.txt Stage 22 image 050.jpg Stage 22 image 051.jpg Stage 22 image 052.jpg Stage 22 image 053.jpg Stage 22 image 054.jpg Stage 22 image 055.jpg Stage 22 image 056.jpg Stage 22 image 057.jpg Stage 22 image 058.jpg Stage 22 image 059.jpg Stage 22 image 060.jpg Stage 22 image 061.jpg Stage 22 image 062.jpg Stage 22 image 063.jpg Stage 22 image 064.jpg Stage 22 image 065.jpg Stage 22 image 066.jpg Stage 22 image 067.jpg Stage 22 image 068.jpg Stage 22 image 069.jpg Stage 22 image 070.jpg Stage 22 image 071.jpg Stage 22 image 072.jpg Stage 22 image 073.jpg Stage 22 image 074.jpg Stage 22 image 075.jpg Stage 22 image 076.jpg Stage 22 image 077.jpg Stage 22 image 078.jpg Stage 22 image 079.jpg Stage 22 image 080.jpg Stage 22 image 081.jpg Stage 22 image 082.jpg Stage 22 image 083.jpg Stage 22 image 084.jpg Stage 22 image 085.jpg Stage 22 image 086.jpg Stage 22 image 087.jpg Stage 22 image 088.jpg Stage 22 image 089.jpg Stage 22 image 090.jpg Stage 22 image 091.jpg Stage 22 image 092.jpg Stage 22 image 093.jpg Stage 22 image 094.jpg Stage 22 image 095.jpg Stage 22 image 096.jpg Stage 22 image 097.jpg Stage 22 image 098.jpg

Link Files

Unlabeled

Stage 22 (serial unlabeled images): 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49


Labeled

Stage 22 (serial labeled images): | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98

Table with numbers

Stage 22 (serial unlabelled images)
Stage 22 image 001.jpg Stage 22 image 002.jpg Stage 22 image 003.jpg Stage 22 image 004.jpg Stage 22 image 005.jpg Stage 22 image 006.jpg Stage 22 image 007.jpg
1 2 3 4 5 6 7
Stage 22 image 008.jpg Stage 22 image 009.jpg Stage 22 image 010.jpg Stage 22 image 011.jpg Stage 22 image 012.jpg Stage 22 image 013.jpg Stage 22 image 014.jpg
8 9 10 11 12 13 14
Stage 22 image 015.jpg Stage 22 image 016.jpg Stage 22 image 017.jpg Stage 22 image 018.jpg Stage 22 image 019.jpg Stage 22 image 020.jpg Stage 22 image 021.jpg
15 16 17 18 19 20 21
Stage 22 image 022.jpg Stage 22 image 023.jpg Stage 22 image 024.jpg Stage 22 image 025.jpg Stage 22 image 026.jpg Stage 22 image 027.jpg Stage 22 image 028.jpg
22 23 24 25 26 27 28
Stage 22 image 029.jpg Stage 22 image 030.jpg Stage 22 image 031.jpg Stage 22 image 032.jpg Stage 22 image 033.jpg Stage 22 image 034.jpg Stage 22 image 035.jpg
29 30 31 32 33 34 35
Stage 22 image 036.jpg Stage 22 image 037.jpg Stage 22 image 038.jpg Stage 22 image 039.jpg Stage 22 image 040.jpg Stage 22 image 041.jpg Stage 22 image 042.jpg
36 37 38 39 40 41 42
Stage 22 image 043.jpg Stage 22 image 044.jpg Stage 22 image 045.jpg Stage 22 image 046.jpg Stage 22 image 047.jpg Stage 22 image 048.jpg Stage 22 image 049.jpg
43 44 45 46 47 48 49

Labeled Icon Table (80px)

Stage 22 (serial labelled images)
Stage 22 image 050.jpg Stage 22 image 051.jpg Stage 22 image 052.jpg Stage 22 image 053.jpg Stage 22 image 054.jpg Stage 22 image 055.jpg Stage 22 image 056.jpg
Stage 22 image 057.jpg Stage 22 image 058.jpg Stage 22 image 059.jpg Stage 22 image 060.jpg Stage 22 image 061.jpg Stage 22 image 062.jpg Stage 22 image 063.jpg
Stage 22 image 064.jpg Stage 22 image 065.jpg Stage 22 image 066.jpg Stage 22 image 067.jpg Stage 22 image 068.jpg Stage 22 image 069.jpg Stage 22 image 070.jpg
Stage 22 image 071.jpg Stage 22 image 072.jpg Stage 22 image 073.jpg Stage 22 image 074.jpg Stage 22 image 075.jpg Stage 22 image 076.jpg Stage 22 image 077.jpg
Stage 22 image 078.jpg Stage 22 image 079.jpg Stage 22 image 080.jpg Stage 22 image 081.jpg Stage 22 image 082.jpg Stage 22 image 083.jpg Stage 22 image 084.jpg
Stage 22 image 085.jpg Stage 22 image 086.jpg Stage 22 image 087.jpg Stage 22 image 088.jpg Stage 22 image 089.jpg Stage 22 image 090.jpg Stage 22 image 091.jpg
Stage 22 image 092.jpg Stage 22 image 093.jpg Stage 22 image 094.jpg Stage 22 image 095.jpg Stage 22 image 096.jpg Stage 22 image 097.jpg Stage 22 image 098.jpg

Labeled Icon Table (100px)

Stage 22 (serial labelled images)
Stage 22 image 050.jpg Stage 22 image 051.jpg Stage 22 image 052.jpg Stage 22 image 053.jpg Stage 22 image 054.jpg Stage 22 image 055.jpg Stage 22 image 056.jpg
Stage 22 image 057.jpg Stage 22 image 058.jpg Stage 22 image 059.jpg Stage 22 image 060.jpg Stage 22 image 061.jpg Stage 22 image 062.jpg Stage 22 image 063.jpg
Stage 22 image 064.jpg Stage 22 image 065.jpg Stage 22 image 066.jpg Stage 22 image 067.jpg Stage 22 image 068.jpg Stage 22 image 069.jpg Stage 22 image 070.jpg
Stage 22 image 071.jpg Stage 22 image 072.jpg Stage 22 image 073.jpg Stage 22 image 074.jpg Stage 22 image 075.jpg Stage 22 image 076.jpg Stage 22 image 077.jpg
Stage 22 image 078.jpg Stage 22 image 079.jpg Stage 22 image 080.jpg Stage 22 image 081.jpg Stage 22 image 082.jpg Stage 22 image 083.jpg Stage 22 image 084.jpg
Stage 22 image 085.jpg Stage 22 image 086.jpg Stage 22 image 087.jpg Stage 22 image 088.jpg Stage 22 image 089.jpg Stage 22 image 090.jpg Stage 22 image 091.jpg
Stage 22 image 092.jpg Stage 22 image 093.jpg Stage 22 image 094.jpg Stage 22 image 095.jpg Stage 22 image 096.jpg Stage 22 image 097.jpg Stage 22 image 098.jpg

Labeled Icon Table (120px)

Stage 22 (serial labeled images)
Stage 22 image 050.jpg Stage 22 image 051.jpg Stage 22 image 052.jpg Stage 22 image 053.jpg Stage 22 image 054.jpg Stage 22 image 055.jpg Stage 22 image 056.jpg
Stage 22 image 057.jpg Stage 22 image 058.jpg Stage 22 image 059.jpg Stage 22 image 060.jpg Stage 22 image 061.jpg Stage 22 image 062.jpg Stage 22 image 063.jpg
Stage 22 image 064.jpg Stage 22 image 065.jpg Stage 22 image 066.jpg Stage 22 image 067.jpg Stage 22 image 068.jpg Stage 22 image 069.jpg Stage 22 image 070.jpg
Stage 22 image 071.jpg Stage 22 image 072.jpg Stage 22 image 073.jpg Stage 22 image 074.jpg Stage 22 image 075.jpg Stage 22 image 076.jpg Stage 22 image 077.jpg
Stage 22 image 078.jpg Stage 22 image 079.jpg Stage 22 image 080.jpg Stage 22 image 081.jpg Stage 22 image 082.jpg Stage 22 image 083.jpg Stage 22 image 084.jpg
Stage 22 image 085.jpg Stage 22 image 086.jpg Stage 22 image 087.jpg Stage 22 image 088.jpg Stage 22 image 089.jpg Stage 22 image 090.jpg Stage 22 image 091.jpg
Stage 22 image 092.jpg Stage 22 image 093.jpg Stage 22 image 094.jpg Stage 22 image 095.jpg Stage 22 image 096.jpg Stage 22 image 097.jpg Stage 22 image 098.jpg

Labeled Icon Table (120px) with numbers

Stage 22 (serial labeled images)
Stage 22 image 050.jpg Stage 22 image 051.jpg Stage 22 image 052.jpg Stage 22 image 053.jpg Stage 22 image 054.jpg Stage 22 image 055.jpg Stage 22 image 056.jpg
50 51 52 53 54 55 56
Stage 22 image 057.jpg Stage 22 image 058.jpg Stage 22 image 059.jpg Stage 22 image 060.jpg Stage 22 image 061.jpg Stage 22 image 062.jpg Stage 22 image 063.jpg
57 58 59 60 61 62 63
Stage 22 image 064.jpg Stage 22 image 065.jpg Stage 22 image 066.jpg Stage 22 image 067.jpg Stage 22 image 068.jpg Stage 22 image 069.jpg Stage 22 image 070.jpg
64 65 66 67 68 69 70
Stage 22 image 071.jpg Stage 22 image 072.jpg Stage 22 image 073.jpg Stage 22 image 074.jpg Stage 22 image 075.jpg Stage 22 image 076.jpg Stage 22 image 077.jpg
71 72 73 74 75 76 77
Stage 22 image 078.jpg Stage 22 image 079.jpg Stage 22 image 080.jpg Stage 22 image 081.jpg Stage 22 image 082.jpg Stage 22 image 083.jpg Stage 22 image 084.jpg
78 79 80 81 82 83 84
Stage 22 image 085.jpg Stage 22 image 086.jpg Stage 22 image 087.jpg Stage 22 image 088.jpg Stage 22 image 089.jpg Stage 22 image 090.jpg Stage 22 image 091.jpg
85 86 87 88 89 90 91
Stage 22 image 092.jpg Stage 22 image 093.jpg Stage 22 image 094.jpg Stage 22 image 095.jpg Stage 22 image 096.jpg Stage 22 image 097.jpg Stage 22 image 098.jpg
92 93 94 95 96 97 98

Original System Descriptions

(Some Links will not function, section naming has been changed)


Cardiovascular System Development- Stage 22

Introduction

This page shows the Carnegie stage 22 embryo images that relate to cardiac development. The small image excerpts show specific features, which can then be observed in the linked complete sections.

Stage 22 Embryo

These are scaled image excerpts, click on image or section name to see full size section for details.


File:E4.gif E4: In centre of picture, portion of left ventricle wall.

Righthandside- body wall.

Lefthand side- diaphragm and liver.

Centre bottom- oseophagus, thoracic aorta, and inferior vena cava.

File:E3.gif E3: Section through all four chambers of heart.

Ventricles. Diaphragm and liver. Pericardium and cavity. R atrium and two cusps of the atrioventricular valve. L atrium and its auricle. Thoracic aorta. Inferior vena cava. Coronary sinus.

File:E2.gif E2: Section through all four chambers of heart.

Ventricles. Right venous valve. Between the tiny ridge of the septum secundum of the R atrium and the R venous valve.

right atrium- drainage of the inferior vena cava (cf. E3). R atrioventricular canal. Septum primum.

left atrium- drainage sites of R and L pulmonary veins.

File:E1.gif E1: Section through all four chambers of heart.

left ventricle- outflow tract close to origin of ascending aorta. Deep coronary sulcus and transverse pericardial sinus.

right atrium- R venous valve of the inferior vena cava, the small septum secundum, the aperture in the dorsal part of septum primum (ostium secundum). (The foramen ovale arises later with the elongation of the septum secundum).

left atrium- entrance of the L and R pulmonary veins and the auricle.

File:D7.gif D7: R atrium with R venous valve. R ventricle close to origin of pulmonary trunk. L.ventricular wall and three semilunar valves of aortic ostium.
File:D6.gif D6: Superior vena cava. Ascending aorta with transverse pericardial sinus behind. Semilunar valve at origin of pulmonary trunk. L. atrium and auricle. Thoracic aorta.
File:D5.gif D5: Superior vena cava. Ascending arch of aorta. Pulmonary trunk with the other two semilunar valves.

Sinus above one valve and branching of pulmonary trunk into L and R pulmonary arteries.

File:D4.gif D4: Ascending aorta. Pulmonary trunk and arteries. Thoracic aorta. Oesophagus. Bronchi. Note azygos vein on right, and precursor of hemiazygos vein on left side.

(Image excerpt different scale from previous images)

File:D3.gif D3: Ascending aorta attached cranial to transverse pericardial sinus. Superior vena cava expanding into R jugular vein. Trachea (bifurcation). Oesophagus. Azygos (R) and hemiazygos (L) veins.
File:D2.gif D2: Aortic arch. L jugular lymph sac lying laterally with hemiazygos joining it. Trachea. Oesophagus. Draining of azygos vein into R jugular vein.
File:D1.gif Dl: Aortic arch. Thymus (retrosternal). Trachea. Oesophagus. Large L and R jugular veins.
File:C7.gif C7: L brachiocephalic vein (transverse anastomosis of L, R jugular veins). L common carotid artery. Brachiocephalic trunk.
File:C6.gif C6: L and R common carotid arteries. L and R internal jugular veins.


Coelomic Cavity Development

Introduction

The intraembryonic coelom is the primitive cavity that lies within the developing embryo that will form the 3 major body cavities: pericardial, pleural, peritoneal. The coelom forms very early in embryogenesis and is much later paritioned inferiorly by the diaphragm and pleuroperitoneal membrane; and superiorly initially by the pleuropericardial fold between the heart and lungs.

The intraembryonic coelom communicated through coelomic portals (at the level of midgut herniation) with the extraembryonic coelom.

All cavities are fluid filled and developing organs push against a wall of the cavity, generating a double coat (serosal/adventital) surrounding an organ (for example the lungs). The serous membrane is the epithelium (squamous) and its associated underlying loose connective tissue.


==== Stage 22 Embryo (Human) ====


In the human embryo, the separation of the three cavities of coelom is complete.

D1-7&E1-4 : The pericardial cavity.

Dl-7, E1-7: The pleural cavity, almost the same frames, indicating the nearby equal extent of the two cavities at this stage, but also that eventually the pleural cavities will become much larger. E3-7: The diaphragm can be seen as a thin, distinct membrane around the liver. Two derivatives of the coelomic epithelium are to be observed here.

E6-7, F1-3: The adrenal glands. Notice the large fetal cortex, (most of the gland) and the narrow (more compact and darker staining) early permanent cortex encapsulating it.

F1-3: The spleen develops in the dorsal mesogastrium and appears as a dense body on it lateral to the left adrenal gland and kidney. Review in Endocrine Development.

F3-7, G1: The gonads are also in part derivatives of the coelomic epithelium but they will be discussed with the rest of the genital system.

G4-5: The caudal extent of the peritoneal cavity; this appears as the rectovesical pouch in the male or as the rectouterine pouch in the female.

 

Reading

  • Human Embryology (2nd ed.) Larson
    • Ch6 p127-146
  • The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud
    • Ch9: p174-184
  • Before we Are Born (5th ed.) Moore and Persaud
    • Ch10 p181-195
  • Essentials of Human Embryology Larson
    • Ch6 p81-93
  • Human Embryology Fitzgerald and Fitzgerald
    • Ch5 p29-32, Ch7 p47,48
  • Additional References
  • Search PubMed- [coelom2.htm#PubMed Medline]

Objectives

  • Describe the development of the intra- and extra-embryonic coeloms.
  • Describe the processes involved in the development of the three divisions of the intra-embryonic coelom; pericardium, pleural cavities and peritoneum.
  • Describe the fate of the extra embryonic coelom.
  • Describe the development of the diaphragm.

Learning activities

  • Review the development of the 3-layered embryo, with particular reference to the antero-posterior and lateral folding processes.
  • Examine the 6mm pig and 27mm human embryo microfiche cards identifying the main features of the developing coelom.
  • Identify the diaphragm in the 27mm human embryo and relate this to the development of the diaphragm.
  • Discuss the developmental anomalies associated with the formation of the diaphragm.

Computer Activities

UNSW Embryology: [coelom3.htm Pig coelom sections (st13/14) | ][coelom4.htm Human coelom sections (st22) | ][coelom4.htm#high%20power Selected Human highpower (st22)]

Human Embryology Movies:

Embryo Images Unit: Body Cavities (Early Week 4) | Body Cavities (Late Week 4)

Development Overview

Image 004.gifCartoon of the intraembryonic coelom forming in the lateral plate mesoderm


==== Extraembryonic Coelom ====
cavity surrounding the developing embryo
coelomic portalstransient communication between extra/intracoelom
==== Intraembryonic Coelom ====
horseshoe shaped structure forms 3 main cavities
==== Neural Tube ====


percardial cavity
Ventricular space
L/R pleural cavities
Spinal canal
peritoneal cavity
(not part of this section)(see neural dev notes)

Mesothelia

The epithelial covering of coelomic organs and also line their cavities.

Contribute to the vasculature of the heart and the intestinal tract. Undergo epithelial-mesenchymal transition (EMT), migration, and differentiation into endothelial cells, vascular smooth muscle cells, and pericytes.


Development of the Kidney and Reproduction Systems

Stage 22 Urogenital 3D Model

The individual serial slices have also been incorporated into a 3D model of this embryo [UG3dmodelst22.htm Urogenital System].

Stage 22 Embryo (Human) Urinary System

E6: R,L adrenal glands under diaphragm.

E7: Large adrenal glands. Inferior vena cava. Thoracic aorta.

File:Hf1.gif File:Hf2.gif File:Hf3.gif
Fl: Adrenal glands. R. Kidney. Autonomic ganglia (partly the adrenal medulla precursors). F2: Kidneys (note retroperitoneal location). Cortex. Medulla. L. Adrenal gland. Superior mesenteric artery. Inferior vena cava. F3: R testis (note its location relative to the R adrenal). L adrenal. R renal hilus. large channels are branches of ureteric tree.
File:Hf4.gif File:Hf5.gif File:Hf6.gif File:Hf7.gif
F4: R kidney and R ureter. Inferior vena cava. L. kidney, L renal hilus and L ureter. R testis with R mesonephric duct (precursor of vas deferens). L testis. Umbilical arteries passing into umbilical cord allantois between them. F5: Kidneys. Ureters. Note umbilical arteries and allantois. Also note how R testis and mesonephric structures are attached to parietal peritoneum by a mesogonad. F6: Kidneys. Ureters. Note umbilical arteries and allantois. Also note how R testis and mesonephric structures are attached to parietal peritoneum by a mesogonad. F7: In F7, (dorsal to R testis and liver) note with the distinct lumen of the mesonephric duct, almost solid column of paramesonephric cells and remnants of mesonephric tubules. "mesogonad". Ureters. Bladder with submucosa and detrusor muscle. Umbilical arteries. Division of aorta.
File:Hg1.gif File:Hg2.gif File:Hg3.gif File:Hg4.gif
G1: Ureters, Bladder. Umbilical arteries. Testis with remains of mesonephros (dorsal), mesonephric duct and paramesonephric cells. Sigmoid colon and mesocolon. G2: Ureters being displaced ventrally, crossing common iliac arteries. Sigmoid colon. Bladder. Mesonephric ducts (lateral) and paramesonephric ducts (smaller, medial) located dorsal to bladder. G3: Ureters (cut twice): descending dorsal to bladder and ascending ventrally to enter the bladder at trigone, through the submucosa). Fusion of paramesonephric ducts. Paired mesonephric ducts. Umbilical arteries looping off common iliac arteries. Pubic symphysis. Colon. G4: Most caudal part of loop of ureters. Urethra emerging from bladder. Mesonephric ducts. Rectocolic junction.
File:Hg5.gif File:Hg6.gif File:Hg7.gif
G5: Urethra (in region of future prostate gland - note crescentic shape). Rectum. Rectovesical pouch. Between G4 and G5, each mesonephric duct (vas deferens) has joined the prostatic urethra (caudal to the ureters), thereby increasing the caliber of the latter. G6: Penile urethra, emerging inferiorly to the glans penis. Scrotal swellings (appear before testis descends). G7: Penile urethra, emerging inferiorly to the glans penis. Scrotal swellings (appear before testis descends). Note F7 MS term: "inebriated Puffin" (dorsal to R testis and liver) lumen of the mesonephric duct (eye), almost solid column of paramesonephric cells (beak) and remnants of mesonephric tubules (body).

 


Stage 22 Embryo (Human) Genital System (Male) ([#Female also see Female])
File:Hf3.gif File:Hf4.gif File:Hf5.gif File:Hf6.gif
F3: R testis with thick tunica albuginea (pale) and thin urogenital mesentery.Note spleen on L. F4: Testes. Narrow urogenital mesentery. Remains of mesonephric tubules near hilus (future efferent ductules at mediastinum testis). F5: Broader urogenital mesentery on R (still narrow on L). F6: On R: Remnants of mesonephric tubules (primordia of ductuli efferentes). Mesonephric duct (origin of vas deferens). Laterally, the paramesonephric duct (primordia of appendix testis). Note abdominal location of testes in relation to adjacent structures.
File:Hf7.gif File:Hg1.gif File:Hg2.gif File:Hg3.gif
F7: Developing efferent ductules, mesonephric duct and medially, the paramesonephric duct (appearing solid). Note how the paramesonephric duct crossed the mesonephric duct ventromedially. Urogenital mesentery - note how testis is attached to the developing efferent ductules by a separate narrow flange,the mesorchium. G1: On R: Lateral mesonephric duct and medial paramesonephric groove. (Changing from a tube to a groove). On L: testis (lower than on R), mesonephric tubules, mesonephric duct (lateral), paramesonephric duct (ventromedial - appearing solid).Bladder. Umbilical arteries. Sigmoid colon and mesocolon. G2: Transition from abdominal cavity to superior pelvis. note iliac crest, femoral nerve, psoas major muscle, internal iliac vein and artery. Medial convergence of paramesonephric cords and more laterally-located mesonephric ducts, ventral to the colon and dorsal to the bladder. Note position of ureters. N.B. Testis lies above this level which is close to the plane of the future inguinal canal. G3: Transition from superior (major) pelvis to inferior (minor) pelvis. Rectovesical pouch. Note wide expanse of loose tissue ventral to the pubic symphysis: site of testicular descent.
File:Hg4.gif File:Hg5.gif File:Hg6.gif File:Hg7.gif
G4: Transition from superior (major) pelvis to inferior (minor) pelvis. Rectovesical pouch. Note wide expanse of loose tissue ventral to the pubic symphysis: site of testicular descent. External genitalia (male)G5: Minor pelvis. Obturator foramen. Ischium. Head of femur. Acetabulum. Ganglion cells of pelvis plexus. Obturator externus muscle. Urogenital sinus (the caudal enlargement is due to junction of mesonephric ducts). G6:Level of pelvic floor. Pelvic plexus. Recto-anal junction. Ischium. obturator internus muscle. Greater sciatic notch. Alar of sacrum. Sacro-iliac joint. G7: Urethra opening ventrally. Genital tubercle (embryonic glans penis).


Endocrine Development Stage 22

Introduction

By stage 22 thre are now visible many components of the endocrine system. Note the appearance and position of the glands within the embryo. In particular, the now more mature Thyroid and the more structured Pituitary.

Both these and other endocrine glands of this stage can be seen in more detail on the [endocrine5.htm Selected Stage 22] page.

Stage 22

List of serial section images containing endocrine components.

A6: Thalamus/hypothalamus.

B2: Neurohyophysis and adenohypophysis. Remnant of Rathke's pouch (residual lumen) in adenohypophysis.

B3: Adenohypophysis.

C3: Glottic region with cricoid cartilage and descending process of thyroid cartilage laterally.

C4: Section damaged, but shows thyroid gland lateral to trachea.

C5: Thyroidgland.

Dl: Thymus gland.

E6: R,L adrenal glands under diaphragm.

E7: Large adrenal glands.

Fl: Adrenal glands. R. Kidney. Autonomic ganglia (partly the adrenal medulla precursors).

F2: Kidneys (note retroperitoneal location). Cortex. Medulla. L. Adrenal gland.


=== Development of the organs of Vision, Audition, Equilibrium and Olfaction

Introduction

Embryo Stage 22 - Eye

File:Ha6.gif A6:Interorbital ligament. Nose. uppereyelids. Cornea. Anteriorchamber. Lens. Vitreous body. Sensory retina. optic ventricle (artefact). Pigment epithelium. Conjunctivalsac. Primordium of lacrimal glands (near lateral fornix of conjunctival sac).
File:Ha7.gif A7: Medial rectus m. Primordium of nasolacrimal ducts. Upper eyelid (lateral). Lower eyelid (medial).
File:Hb1.gif B1: Optic nerve. Note extensive temporal region of retina. Primordium of nasolacrimal ducts.
File:Hb2.gif B2: Medial and lateral rectus muscles. Pigment epithelium. Note relationship of eye to nasal capsule, sphenoid cartilage and trigeminal ganglion. Primordium of nasolacrimal ducts (cut obliquely).
File:Hb3.gif B3: On left, note course of maxillary division of trigeminal in relation to position of eye (superior to this level).

 

Embryo Stage 22 - Ear

File:Hb3ear.gif B3: Rhombic lip (developing cerebellum). IVth ventricle. Trigeminal ganglion. Adenohypophysis. Sphenoid cartilage.
File:Hb4ear.gif B4: Cochlear duct and temporal cartilage. Semicircular duct (ampulla on L). precartilage of auricle (pinna). malleus (medial, L). Incus (lateral, L).
File:Hb5.gif B5: Extemal auditory meatus. Auricle. Incus (dorsal). Malleus (ventral). Tubotympanic recess (auditory rube). Tensor tympani m. (L). Utricle. Semicircular ducts. Intemal auditory meatus (R), containing vestibular and spiral ganglia. Endolymphatic sac (L). Note proximity of sac to choroid plexus of 4th ventricle.
File:Hb6.gif B6: External auditory meatus. Primordium of tympanic membrane (L). Manubrium of malleus(L). Basal turn of cochlea duct (L). Endolymphatic sac (R). Common crus (R). Junction of utricle and saccule (R). Meckel's cartilage. Stapes (R). Auditory tube.

 

Embryo Stage 22 - Nose

File:Ha6n.gif A6: Interorbital ligament. nasal septum. primitive olefactory epithelium
File:Ha7n.gif A7: Interorbital ligament. nasal septum. superior concha and meatus. primitive olefactory epithelium
File:Hb1n.gif B1:
File:Hb2n.gif B2: vomeronasal organs (dark spots) beside nasal septum
File:Hb3n.gif B3: nasolacrimal ducts
File:Hb4n.gif B4: tongue
File:Hb5n.gif B5: unfused palatale shelves either side of tongue. section through mandible (top of image).

 



Head and Neck Development - Stage 22

Introduction

This current page gives a brief overview of late embryonic development (Carnegie stage 22) in the head and neck region.

File:CSt22.gif
Stage 22 embryo

Stage 22 Embryo

Optic and Nasal region of head.


Stage 22 Embryo - Sections by Text

A text description linked to the actual embryo cross-section.

A5: Root of nose with interorbital ligament behind. Developing calvaria. Olfactory bulbs.

A6: Nose. Interorbital ligament. Nasal septum and nasal capsule. Eyes and eyelids. Thalamus/hypothalamus. Part of circle of Willis.

A7: Eyes. Nasal septum. Middle conchae. Sphenoid cartilage.

B1: Optic nerve.

B2: Neurohyophysis and adenohypophysis. Remnant of Rathke's pouch (residual lumen) in adenohypophysis. Trigeminal ganglion. Internal carotid arteries. Vomeronasal organs, lateral to nasal septum. Nasal plug (transient). Nasal conchae.

B3: Trigeminal nerve and ganglion, with maxillary division emerging. Pterygopalatine ganglion. Nasalconchae. Adenohypophysis.

B4: Tongue. Otic capsule. Cochlea. Between B3 and B4, the junction of nasopharynx and oropharynx.

B5: Tongue with palatal process either side. Pharyngotympanic tubes (Eustachian tube -derived from pharyngeal pouch 1). External ear pinna.

Overview of Pharynx

From level of tongue (B6) to bifurcation of the bronchi (D5-D6).


B4: Tongue. Otic capsule. Cochlea. Between B3 and B4, the junction of nasopharynx and oropharynx.

B5: Tongue with palatal process either side. Pharyngotympanic tubes (Eustachian tube -derived from pharyngeal pouch 1). External ear pinna.

B6: External auditory meatus (from pharyngeal groove 1). Meckel's cartilage with mandible ossifying lateral to it. Tongue with intrinsic muscles. palatal processes.Developing teeth.

B7: Pharynx (compressed dorsoventrally). Mylohyoid muscle and submandibular gland. Platysma muscle (R side). Junction of sigmoid sinus and internal jugular vein on one side. Vagal ganglia (medial). Vertebral arteries.

C1: Pharynx. Carotid neurovascular bundle with prominent ganglia.

C2: Pharynx. Carotidneurovascularbundle. Sternomastoidmuscle.

C3: Glottic region with cricoid cartilage and descending process of thyroid cartilage laterally. Carotidneurovascularbundle.

C4: Section damaged, but shows thyroid gland lateral to trachea. Oesophagus.

C5: Thyroidgland. Trachea. Oesophagus. Recurrent laryngeal nerve. Common carotid arteries. Jugular veins. Vagus nerves.

C6,C7: Jugular veins. In C7 brachiocephalic vein.

Dl: Thymus gland.


Musculoskeletal Development - Stage 22

Introduction

This page looks at musculoskeletal structure and events that occur at late embryonic Carnegie stage 22.

Axial Skeleton

The axial skeleton consists of: Skull, Auditory Ossicles, Hyoid bone, Vertebral column, Chest (sternum, ribs)

The vertebral column is a series of bone segments (vertebra) separated by specialized joints (intervertebral disc). In the adult, these vertebral elements are made up of rostro-caudally: 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, coccyx.

The axial skeleton is derived from mesoderm forming paraxial mesoderm forming somites from which part forms scleretomes forming vertebra and intervertebral discs (More? [../MolDev/vertebra.htm Molecular - Vertebral Column]).


File:Hd1.gif D1,D2: Vertebral body (centrum). Head of rib. Lamina of vertebral arch. Transverse processes. Vertebral canal. Spinal cord. Dura. Intervertebral foramen containing dorsal root ganglion (now in a ventral position!). Ribs. Sympathetic ganglia. Costovertebral and costotransverse joints. Note that laminae of the arches have not fused dorsally but are united by a connective tissue membrane (dorsal uniting membrane or ligament) which provides the guide-path for the growth and subsequent fusion of the laminae. The dura constitutes the ventral uniting membrane or ligament. Part of intervertebral disc seen in D2.
File:Hd3.gif D3: Ganglia in intervertebral foramina. Costovertebral joint.
File:Hd4no2.gif[1]File:Hd4.gif D4: Anteriorly, note ribs joining the sternum and intercostal muscles

 

 

 

D4: Pedicle of vertebral arch. The dark, fibrous tissue at the anterior margin of the vertebral column is the intervertebral disc (derived from dark part of sclerotome). Note erector spinae group of muscles.

File:He4.gif E4: Vertebral body with intervertebral disc ventrally. Notochord remnant at junction of body and intervertebral disc.
File:He6.gif E6: Next vertebral body (notochord incorporated into cartilage).
File:Hf1.gif F1: Mostly intervertebral disc with notochord remnant
File:Hf2.gif F2: Transverse abdominal muscle, internal and external oblique abdominal muscle, rectus abdominis muscles.
File:Hf7.gif File:Hg1.gif F7,G1: (Lumbar cross-section). Vertebral body and I.V. disc. Psoas major muscle. Erector spinae muscles. Note short laminae of the arches and wide dorsal uniting ligament.

Links: [../MolDev/vertebra.htm Molecular - Vertebral Column] |

Appendicular Skeleton

The appendicular skeleton consists of: Shoulder girdle, Upper limb (arm, hand), Pelvic girdle, Lower limb (leg, foot).


==== Lower limb (Row G) ====
File:Hg1no2.gif File:Hg2.gif
G1: Knee mesenchyme G2: Patella. Femur. Flexor and extensor muscles.
File:Hg4.gif File:Hg5.gif
G4: Knee joint. Tibia and femur. Hip bone: pubis, ischium, ilium, head of femur. Developing acetabulum. Adductor group of muscles. G5: Hip joint. Acetabulum. Head and greater trochanter of femur. Sacro-iliac joint.
File:Hg6.gif File:Hg7.gif
G6: Heel. Ischium. Sacro-iliac joint. G7: Tarsal cartilages (note inverted position of feet). Heel. Phalangeal cartilages.


Musculoskeletal Development - Stage 22

Introduction

This page looks at musculoskeletal structure and events that occur at late embryonic Carnegie stage 22.

Axial Skeleton

The axial skeleton consists of: Skull, Auditory Ossicles, Hyoid bone, Vertebral column, Chest (sternum, ribs)

The vertebral column is a series of bone segments (vertebra) separated by specialized joints (intervertebral disc). In the adult, these vertebral elements are made up of rostro-caudally: 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, coccyx.

The axial skeleton is derived from mesoderm forming paraxial mesoderm forming somites from which part forms scleretomes forming vertebra and intervertebral discs (More? [../MolDev/vertebra.htm Molecular - Vertebral Column]).


File:Hd1.gif D1,D2: Vertebral body (centrum). Head of rib. Lamina of vertebral arch. Transverse processes. Vertebral canal. Spinal cord. Dura. Intervertebral foramen containing dorsal root ganglion (now in a ventral position!). Ribs. Sympathetic ganglia. Costovertebral and costotransverse joints. Note that laminae of the arches have not fused dorsally but are united by a connective tissue membrane (dorsal uniting membrane or ligament) which provides the guide-path for the growth and subsequent fusion of the laminae. The dura constitutes the ventral uniting membrane or ligament. Part of intervertebral disc seen in D2.
File:Hd3.gif D3: Ganglia in intervertebral foramina. Costovertebral joint.
File:Hd4no2.gif[2]File:Hd4.gif D4: Anteriorly, note ribs joining the sternum and intercostal muscles

 

 

 

D4: Pedicle of vertebral arch. The dark, fibrous tissue at the anterior margin of the vertebral column is the intervertebral disc (derived from dark part of sclerotome). Note erector spinae group of muscles.

File:He4.gif E4: Vertebral body with intervertebral disc ventrally. Notochord remnant at junction of body and intervertebral disc.
File:He6.gif E6: Next vertebral body (notochord incorporated into cartilage).
File:Hf1.gif F1: Mostly intervertebral disc with notochord remnant
File:Hf2.gif F2: Transverse abdominal muscle, internal and external oblique abdominal muscle, rectus abdominis muscles.
File:Hf7.gif File:Hg1.gif F7,G1: (Lumbar cross-section). Vertebral body and I.V. disc. Psoas major muscle. Erector spinae muscles. Note short laminae of the arches and wide dorsal uniting ligament.

Links: [../MolDev/vertebra.htm Molecular - Vertebral Column] |

Appendicular Skeleton

The appendicular skeleton consists of: Shoulder girdle, Upper limb (arm, hand), Pelvic girdle, Lower limb (leg, foot).


==== Lower limb (Row G) ====
File:Hg1no2.gif File:Hg2.gif
G1: Knee mesenchyme G2: Patella. Femur. Flexor and extensor muscles.
File:Hg4.gif File:Hg5.gif
G4: Knee joint. Tibia and femur. Hip bone: pubis, ischium, ilium, head of femur. Developing acetabulum. Adductor group of muscles. G5: Hip joint. Acetabulum. Head and greater trochanter of femur. Sacro-iliac joint.
File:Hg6.gif File:Hg7.gif
G6: Heel. Ischium. Sacro-iliac joint. G7: Tarsal cartilages (note inverted position of feet). Heel. Phalangeal cartilages.


Neural System Development- Stage 22

Stage 22 Neural 3D Model

The individual serial slices have also been incorporated into a 3D model of this embryo [../Movies/CNS3dmodelst22.htm Neural System].

Serial Section Descriptions

Al-4 In the human embryo identify the large telencephalic vesicles and the choroid plexus. The cavity in these (the lateral ventricles) communicate with the ventricle of the diencephalon (3rd ventricle) through the interventricular foramen

A3: inside the lateral ventricle

Al-2: Distinguish the wall of the forebrain.

A3-4: The basal part of the telencephalon forms the basal ganglia, a solid mass. Posteromedially these basal ganglia are in contact with the diencephalon. The large masses in either side of the diencephalon form the thalami.

Al-7, B1: The diencephalon. In these levels the brain comes into section twice, because of the cephalic flexure, but in A2-4 the two parts are connected.

Al-5: Ventral to the thalamus you can identify the hypothalamus.

A6-7, B1: The hypothalamus

A6: the lamina terminalis, original anterior end of the neural tube. Notice the position of the optic nerves in relation to the hypothalamic part of the diencephalon (B1).

B2-3: Further caudally the pituitary gland is seen, the neural part of which is a derivative of the diencephalon.

Al-7: The midbrain (mesencephalon). Its dorsal part is the mesencephalic vesicle, a large, thin-walled structure (A2-6) which overlaps the initial part of the metencephalon (A6-7).( The ventral part of the mesencephalon is seen to be continuous with the diencephalon in A3-4. The tectal recess, an extension of the roof the mesencephalic vesicle is seen in A6.

A6: The junction between the mesencephalon and metencephalon is called the isthmus. The main metencephalic derivatives are the pons and cerebellum.

The ventricular lumen of the hind brain is the 4th ventricle (A7, B1-7, C1-3). The roof of the metencephalic part of the 4th ventricle is formed by the developing cerebellum (B2-3), beyond which the ventricle forms two large lateral recesses (B2-3). In more caudal sections the roof of the ventricle is seen as a thin membrane only, bearing choroid plexus.

B2-3: the root of the trigeminal nerve and its ganglion.

The myelencephalic part of the hind brain will form the medulla oblongata, the embryonic appearance of which is hardly different from the fully developed structure. The vagus nerve and its ganglion are seen to leave the base of the brain in B7, through the jugular foramen.

At all levels where the brain is present notice the meninges enveloping it and creating the large subarachnoid space which is filled with cerebrospinal fluid.

Study the histological appearance of the spinal cord. Note the alar and basal laminae, the dorsal root ganglia and the sympathetic trunk.