Neural System - Carnegie Stage 22

From Embryology

Introduction

Stage22-CNS-icon.jpg There individual serial slices have also been incorporated into a 3D model of this embryo.
Central Nervous


Neural Links: neural | ventricular | ectoderm | Stage 22 | gliogenesis | neural fetal | Medicine Lecture - Neural | Lecture - Ectoderm | Lecture - Neural Crest | Lab - Early Neural | neural crest | Sensory | neural abnormalities | folic acid | iodine deficiency | Fetal Alcohol Syndrome | Postnatal | Postnatal - Neural Examination | Histology | Historic Neural | Category:Neural
| Carnegie stage 22
Stage 22 (serial labeled images)
Section Name Description
Stage 22 image 050.jpg A1L A1 - A4 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.

A1-A7, 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.

A1-5 Ventral to the thalamus you can identify the hypothalamus.

Stage 22 image 051.jpg A2L Distinguish the wall of the forebrain.
Stage 22 image 052.jpg A3L A3 - A4The 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.
Stage 22 image 053.jpg A4L Description
Stage 22 image 054.jpg A5L Description
Stage 22 image 055.jpg A6L A6-A7, B1 The hypothalamus.

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 (A7L, 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 (B2L-B3L). In more caudal sections the roof of the ventricle is seen as a thin membrane only, bearing choroid plexus.

Stage 22 image 056.jpg A7L Description
Stage 22 image 057.jpg B1L Description
Stage 22 image 058.jpg

Stage 22 image 059.jpg

B2L


B2L

B2-B3 Further caudally the pituitary gland is seen, the neural part of which is a derivative of the diencephalon.

B2-B3 The trigeminal ganglion (CNV or CN5) and the trigeminal nerve.


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.

All Sections

Stage 22L 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
A1L A2L A3L A4L A5L A6L A7L
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
B1L B2L B3L B4L B5L B6L B7L
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
C1L C2L C3L C4L C5L C6L C7L
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
D1L D2L D3L D4L D5L D6L D7L
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
E1L E2L E3L E4L E5L E6L E7L
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
F1L F2L F3L F4L F5L F6L F7L
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
G1L G2L G3L G4L G5L G6L G7L


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. (2018, July 23) Embryology Neural System - Carnegie Stage 22. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_System_-_Carnegie_Stage_22

What Links Here?
© Dr Mark Hill 2018, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G