The document details the developmental changes occurring during the sixth week of human embryonic development, highlighting key processes such as neural tube closure, optical vesicle formation, lung bud branching, and heart chamber development. It explains the size of the embryo at approximately 5-6 mm and describes limb development, bending of the head, and intestinal herniation. This stage involves critical developments that lay the foundation for future bodily functions and structures.

1. ِّ
‫ب‬َّ‫ر‬
‫ي‬‫ن‬ْ‫د‬‫ز‬
‫ا‬ً‫م‬ْ‫ل‬‫ع‬
My Lord, increase me in knowledge

2. 6TH WEEK OF HUMAN
EMBRYONIC DEVELOPMENT
GROUP B
● Aafiya Shoaib
● Ayaz Ahmed
● Hafiz Taimoor
● Kashish Kumari
● Maria Asghar
● Muhammad Huzaifa
● Sadia Fazal
● Syed Taha Alam
● Zunaira Maqsood

3. DEVELOPMENTAL CHANGES IN THE
EMBRYO DURING THE SIXTH WEEK
● Reflex response to touch
● Shows spontaneous movement
● Size of embryo
● Neural tube closure
● Optical vesicle formation
● Lung bud branching
● Heart chamber development
● Limbs development
● Auricular hillocks
● Bending of head
● Intestinal herniation

4. SIZE OF EMBRYO:
● Embryo measures about
approximately 5-6 mm in length.
NEURAL TUBE CLOSURE:
● Neural tube that forms brain & spinal
cord closes.
● Failure of its closure can cause fatal
defect i.e anencephaly

5. OPTICAL VESICLE FORMATION:
● Optic vesicles are the precursor to the eyes. Hence, the eye
development begins.
● The optic vesicle unit invaginates to form retina & lens.

6. LUNG BUD BRANCHING
● Lung buds start to branch forming (primitive) air sacs.
● This lays the foundation of the respiratory system.
● This development enables gaseous exchange, preparing the lungs
for breathing.
HEART CHAMBER DEVELOPMENT:
● The heart tube dives into 4 chapters.
● The septum begins to form.

7. UPPER LIMBS DEVELOPMENT:
● Regional differentiation is exhibited.
● Elbows and hand plates with digital rays
form.
LOWER LIMBS DEVELOPMENT:
● It occurs 4-5 days after upper limb
development.

8. BENDING OF HEAD:
● Head is larger relative to the trunk.
● It is bent over the head prominence.
AURICULAR HILLOCKS:
● The first two pharyngeal arches
contribute to external ear formation.

9. INTESTINAL HERNIATION:
● Trunk and neck begins to straighten.
● Intestine herniates into umbilical cord due to small size
of abdominal cavity.

10. THANK YOU :)