BGDA Practical 12 - Embryo to Fetus

Introduction

• Week 8 Stage 22 and 23
• Selected Stage 22 cross-sections and animations
• Week 10 Fetus

Week 8 Stage 22

stage 22, Week 8, 54 - 56 days, 23 - 28 mm Mesoderm: heart prominence, ossification continues Head: nose, eye, external acoustic meatus Body:straightening of trunk, heart, liver, umbilicus: placental cord, midgut herniation, allantois, vitelline duct Limb: upper limbs longer and bent at elbow, foot plate with webbed digits, wrist, hand plate with separated digits Straightening of trunk, pigmented eye, eyelid, nose, external acoustic meatus, ear auricle, scalp vascular plexus, separated digits (fingers), thigh, ankle, umbilical cord

Embryo Anatomy

Now examine selected regions of the Stage 22 embryo and their overall development in the 3D animations.

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  Head Region

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  Shoulder Region

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  Chest Region

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  Abdomen Region

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  Hip Region

‎‎Systems Page | Play

‎‎GIT Stage 22 Page | Play

‎‎Cardiovascular Page | Play

‎‎Stage 22 Neural Page | Play

‎‎Urogenital Page | Play

‎‎Skeletal Page | Play

Week 8 Stage 23

Week 8, 56 - 60 days, 27 - 31 mm scalp vascular plexus, eylid, eye, nose, auricle of external ear, mouth, sholder, arm, elbow, wrist, toes separated, sole of foot, umbilical cord Mesoderm: ossification continues Head: eyelids, external ears, rounded head Body: straightening of trunk, intestines herniated at umbilicus Limbs: hands and feet turned inward

Week 10 Fetus (40mm)

This is an image of the actual size comparison shown in the introduction of the Embryonic stage 13, 23 and Fetal stage 10 week 40mm. This stage of development is after the embryonic period (up to week 8), but only 2 weeks into early fetal development.

The fetal period is a time of extensive growth in size and mass as well as differentiation of organ systems established in the embryonic period. In particular, the brain continues to grow and develop, the respiratory system differentiates, the urogenital system further differentiates between male/female, endocrine and gastrointestinal tract begins to function. Compare this 10 week fetus with the earlier Carnegie stage embryos: size, head/body proportions, brain, head, skeletal development. Note that in the early fetus the midgut remains herniated and will only be taken into the peritoneal cavity on further body wall growth.

There are 4 sections taken in the sagittal plane (moving from the right at Plane A towards the midline at Plane D). Click on the small images (or the text below) to open the linked large image pages.

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  Planes

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  Plane A

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  Plane B

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  Plane C

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  Plane D

Midgut Herniation

Related Images

Fetus (week 10) Planes A (most lateral), B (lateral), C (medial) and D (midline) from lateral towards the midline.

• Human Fetus - most lateral | lateral | medial | midline

• Head - most lateral | lateral | medial | midline

• Cerebellum - most lateral | lateral | medial | midline

• Urogenital Unlabelled - most lateral | lateral | medial | midline

• Urogenital Labelled - most lateral | lateral | medial | midline

• Large Images - midline

Image Source: UNSW Embryology, no reproduction without permission.

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Additional Information

Links: Fetal Development - 10 Weeks | Stage 22 embryo slices

BGDA: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12 | Lecture Neural | Practical 14 | Histology Support - Female | Male | Tutorial

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

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Cite this page: Hill, M.A. (2024, April 18) Embryology BGDA Practical 12 - Embryo to Fetus. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_12_-_Embryo_to_Fetus

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