UNSW Embryology

Stage 13/14 Embryo Section F1 (labelled)

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St 13/14 Systems -------------- Coelomic Cavity Endocrine Gastrointestinal Head and Neck Heart Musculoskeletal Nervous System Neural Crest Organs of Senses Respiratory System Skin, Hair and Nails Urogenital Placenta

St 13/14 Labelled Embryo Sections A1 A2 A3 A4 A5 A6 A7 B1 B2 B3 B4 B5 B6 B7 C1 C2 C3 C4 C5 C6 C7 D1 D2 D3 D4 D5 D6 D7 E1 E2 E3 E4 E5 E6 E7 F1 F2 F3 F4 F5 F6 F7 G1 G2 G3 G4 G5 G6 G7

St 13/14 Unlabelled Embryo Sections A1 A2 A3 A4 A5 A6 A7 B1 B2 B3 B4 B5 B6 B7 C1 C2 C3 C4 C5 C6 C7 D1 D2 D3 D4 D5 D6 D7 E1 E2 E3 E4 E5 E6 E7 F1 F2 F3 F4 F5 F6 F7 G1 G2 G3 G4 G5 G6 G7

St 13/14 3D Movies Central Nervous System Cardiovasular Gastrointestinal Tract 3D Models

Image Features

Gastrointestinal Development

Fl: Mesentery with midgut loop sectioned in 2 places. Note body wall jelly extending towards sacral region on one side.

F1-F6: Gut loop extending caudally "up" into sacral region, attached by a dorsal mesentery. Separation of dorsal aorta.

F1: Junction of urogenital sinus and midline allantois. Note how this junction lies in the anterior body wall, now separated from the hindgut by the intraembryonic coelom. umbilical artery to one side (missing - damaged - on other side), and umbilical veins further to the side.

Neural Development

F1: Spinal cord has enlarged ventral horns (motor neurons).

Musculoskeletal Development

F1,F2: Caudal limit of forelimb. Broad extensor surface. Dense mesenchyme of hindlimb. Note lumbar somites, somitocoeles.

About Stage 13/14 Embryo

The Carnegie stage 13/14 Pig Embryo is 6mm in size and approximately equal to day 42 Human Embryo. Use the serial images to identify internal features and relationships that exist within the embryo at this stage. Then compare these images with the external appearance of the embryo at this stage and the later internal features of the stage 22 embryo.

Note that the nomenclature "stage 13/14" is not an actual Carnegie stage but indicates that the embryo stage lies between or has features of both stage 13 and stage 14 embryos.

Levels shown on whole embryo are only approximate.

Note that not all embryo features are labelled.

Hint: clicking on each section image above will also step you through the whole embryo in sequence.

UNSW Embryology ISBN: 978 0 7334 2609 4

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