Embryo Lect by Prof Rafeea Tafwwez

8/17/2019 Embryo Lect by Prof Rafeea Tafwwez

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Paranasal Air Sinuses

• Diverticula grow from nasal cavity walls into

surrounding bones

•Openings of outgrowths persist as orifices ofadult sinuses

• At Birth- no frontal or sphenoidal sinuses

• Maillary-!-" mm• Ant # post $thmoidal- %ew cells


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Paranasal Air Sinuses

• $thmoidal- small uptil & yrs grows rapidly

'-( yrs

•Maillary- grows slowly till puberty) fullydeveloped in adulthood

• %rontal grows from ant ethmoidal-&yrs

rapid dev* +yrs

• Sphenidal-grows from post* $th* & yrs


3/18

Pharyngeal arches # primordial

Pharyn


4/18

,aryngotracheal groove


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rachea # Oesophagus


6/18

,aryn" w.s / w.s

'w.s 01 w.s


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Bronchi

• "th w.-lung bud

• /th w.-bronchial buds

• 'th

w.-angiogenetic mesenchyme aroundprim* Br*

• +th w.- tertiary br*) bronchopul* Seg*

%ormed• &" w.s-0+ orders of bronchi formed

• After birth- + orders


8/18

Stages of ,ung Development


9/18

2istogenesis•Splanchnic Mesoderm

3onnective tissue

3artilage

Muscle

3apillaries4isceral pleura

•Somatic Mesoderm

Parietal pleura•$ndoderm

epithelium


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2istogenesis


11/18

Stages of ,ung DevelopmentPseudoglandular phase

• +-0+ w.s

• Development of lower conducting airway # acini

• ,ung resembles eocrine gland

• $pithelium-mesenchyme interactions

• Airway epithelium differentiates

• Mucous glands-0&w.s enlarge) 0" w.s-secretion

• Sm* M # 3 differentiate

• 5o gaseous echange


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Stages of ,ung Development3analicular phase

• 0+-&' w.s

• Overlaps with pseudoglandular phase

• ,umina of bronchi enlarge

• ! generations of branching

• 6esp* br* # alveolar ducts formed

• Saw7toothed margins of distal regions 7acini

• ype 8 # 88 pneumocytes• Surfactant - ' months

• 9aseous echange possible


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Stages of ,ung DevelopmentSacular : terminal sac phase

• &" w.s 7 birth

• More terminal sacs with thin epithelium

• ype 8 # 88 alveolar cells 7 surfactant increases

• 8nterstitial tissue decreases

• 3ap*pleus7double cap* layer between alveoli

• $lastin deposited beneath ep*

• ,ymphatics develop

• %etus can survive if born


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Alveolar phase• ,ate fetal period 7 childhood• hinning of alveolar lining cells) thin

alveolocapillary membrane- gaseous

echange is easy

• 8ncrease in no* of alveoli /1 million at full

term;0:' adult no*<

• %usion of cap* nets of ad=acent alveoli


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racheo-Oesophageal %istula


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3ongenital anomalies of lungs

• ,obe of A>ygous 4

• 3ongenital Pul* 3ysts

• ,ung Agenesis• ,ung 2ypoplasia

• Accessory ,ung

• Abnormal fissures

• Abnormal lobes

Embryo Lect by Prof Rafeea Tafwwez

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