Carnegie stage 3

Introduction

Human blastocyst (day 5) still within zone pellucida.

The free-floating blastocyst has reached the uterine body still enclosed in the zone pellucida and "hatches" from this surrounding extracellular matrix. It is only after hatching that the blastocyst can attach to and then implant into the uterine wall. Facts: Week 1, 4 - 5 days, size 0.1 - 0.2 mm Features: zona pellucida, trophoblast shell, inner cell mass, blastoceol Links: Week 1 | Blastocyst | Lecture | Practical Stage 4

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

Blastocyst Hatching

Human Blastocyst "hatching" from zona pellucida (classified as Carnegie stage 3). Blastocyst is too the right of image and zona pellucida is shown to the left of the image. small opening in the zona pellucida through which the blastocyst is hatching. flattened trophoblast cells forming the outer cell layer of the blastocyst. inner cell mass shown in the centre of the image and on the left-hand wall of the blastocyst. blastocoel forming a large fluid-filled space within the blastocyst.

Blastocyst Development Early development day 3 to 6	Blastocyst Contractions (day 5 to 6)	Blastocyst Hatching (day 5 to 6)

Carnegie Collection

58 cell blastocyst (day 4)	107 cell blastocyst (day 4.5)

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

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Cite this page: Hill, M.A. (2024, April 19) Embryology Carnegie stage 3. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Carnegie_stage_3

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G