DERIVATIVES OF THE ECTODERM
,MESODERM, AND ENDODERM:
DANIL HAMMOUDI.MD
SINOE MEDICAL ASSOCIATION
1/
ECTODERM:
***EPIDERMIS
[INCLUDING HAIR ,NAILS]
***NERVOUS
SYSTEM
***ADRENAL
MEDULLA
2/MESODERM:
***CONNECTIVE
TISSUE
***MUSCLE
***BONE
***CARDIOVASCULAR
***LYMPHATICS
***UROGENITAL
STRUCTURE
***SEROUS
LINING OF BODY CAVITIES [PERITONEAL]
3/ENDODERM
:
***GUT
TUBE EPITHELIUM AND DERIVATIVES
+++LUNG
+++LIVER
+++PANCREAS
NEURAL
CREST DERIVATIVES:
1. ***ANS
DORSAL ROOT GANGLIA
2. ***MELANOCYTES
3. ***CHROMATOFFIN
CELL OF ADRENAL MEDULLA
4. ***ENTEROCHROMAFFIN
CELLS
5. ***PIA
6. ***ARACHNOID
7. ***DURA
8. ***SCHWANN
CELLS
9. ***ODONTOBLASTS
10.***PARAFOLLICULAR
CELLS OF THYROID
AORTIC
ARC DERIVATIVES:
·
1ST: PART OF MAXILLARY ARTERY
·
2ND: STAPEDIAL ARTERY
·
3RD: COMMON CAROTID ARTERY AND PROXIMAL PART OF
INTERNAL CAROTID ARTERY
·
4TH: ON LEFT : AORTIC ARCH
·
ON
RIGHT: PROXIMAL PART OF RIGHT
SUBCLAVIAN ARTERY
·
6TH: PROXIMAL PART OF PULMONARY ARTERY
·
[ON
LEFT ONLY] DUCTUS ARTERIOSUS
·
4TH
ARCH [4LIMBS]=SYSTEMIC
·
6TH
ARCH=PULMONARY TO SYSTEMIC SHUNT [DUCTUS ARTERIOSUS]
BRANCHIAL
ARCH 1 DERIVATIVES:
MECKEL'S CARTILAGE DEVELOPS INTO***
BONES
***MANDIBULE
***MALLEUS
***INCUS
***ANTERIOR
LIGAMENT OF MALLEUS
***SPHENOUS
MANDIBULAR LIGAMENT.
MUSCLES: ***MUSCLES OF MASTICATION
+++TEMPORALIS
+++MASSETER
+++LATERAL
AND MEDIAL PTERYGOIDS
***MYLOHYOID
***ANTERIOR
BELLY OF DIGASTRIC
***TENSOR
TYMPANI
***TENSOR
VELI PALATINI
INNERVATED BY CN V
BRACHIAL
ARCH 2.DERIVATIVES:
REICHERT'S CARTILAGE DEVELOPS INTO
BONES : +++STAPES
+++STYLOID
PROCESS
+++LESSER
HORN OF HYOID
+++UPPER
PART OF HYOID BODY
+++STYLOHYOID
LIGAMENT.
MUSCLES: +++MUSCLES OF FACIAL EXPRESSION
+++STAPEDIUS
+++STYLOHYOID
+++POSTERIOR
BELLY OF DIGASTRIC
INNERVATED BY CN VII
BRACHIAL
ARCH 3 DERIVATIVES:
CARTILAGE DEVELOPS INTO BONE: +++ LOWER PART OF HYOID BODY
+++GREATER
HORN OF HYOID
MUSCLE: +++STYLOPHARYNGEUS
+++UPPER
PHARYNGEAL CONSTRICTORS
INNERVATED BY CN IX.
BRACHIAL
ARCH 4 TO 6 DERIVATIVES:
CARTILAGE: ***THYROID
***CRICOID
***ARYTENOID
***CORNICULATE
***CUNEIFORM
MUSCLE
[4TH ARCH] ***MOST PHARYNGEAL
CONSTRICTORS
***CRICOTHYROID
***LEVATOR
VELI PALATINI.
MUSCLES [6TH ARCH] ***INTRINSIC MUSCLES OF LARYNX
INNERVATED BY CN X [INTRINSIC MUSCLES OF LARYNX BY RECURRENT
BRANCH]
BRANCHIAL
ARCH INNERVATION:
ARCH 1 DERIVATIVES SUPPLIED BY CN V
ARCH 2 DERIVATIVES SUPPLIED BY CN VII
ARCH 3 DERIVATIVES SUPPLIED BY CN IX.
ARCH 4 DERIVATIVES SUPPLIED BY CN X.
BRANCHIAL
PERFORATED [CLEFT] DERIVATIVES:
1 ST CLEFT DEVELOPS INTO EXTERNAL
AUDITORY MEATUS.
2ND THROUGH 4TH CLEFTS FORM TEMPORARY
CERVICAL SINUSES ,WHICH ARE OBLITERATED BY PROLIFERATION OF 2ND ARCH MESENCHYME
PHARYNGEAL
POUCH DERIVATIVES:
1 ST POUCH DEVELOPS INTO MIDDLE
EAR CAVITY ,EUSTACHIAN TUBE ,TYMPANIC
MEMBRANE.
2 ND POUCH DEVELOPS INTO EPITHELIAL
LINING OF PALATINE TONSIL.
3 RD POUCH [DORSAL WINGS] DEVELOPS INTO
INFERIOR PARATHYROIDS.
3 RD POUCH [VENTRAL WINGS] DEVELOPS
INTO THYMUS.
4TH POUCH DEVELOPS INTO SUPERIOR
PARATHYROIDS , ULTIMOBRANCHIAL BODIES.
1 ST POUCH CONTRIBUTES TO ENDODERM
LINED STRUCTURES OF EAR.
3 RD
POUCH CONTRIBUTES TO 3 STRUCTURES ***THYMUS
***L
AND R INFERIOR PARATHYROIDS.
FETAL
ERYTHROPOISIS:
FETAL ERYTHROPOISIS OCCUR IN :
+++YOLK
SAC [3-8 WEEK]
+++LIVER [6-30 WEEK]
+++SPLEEN
[9 WEEK -BIRTH]
+++BONE
MARROW [3RD MONTH AFTER BIRTH ONWARD]
ERYTHROPOISIS IN BONE MARROW DOES NOT
BEGIN UNTIL 1 YEAR AFTER CONCEPTION.
FETAL
POSTNATAL DERIVATIVES:
1/ UMBILICAL VEIN: ***LIGAMENTUM TERES HEPATIS
2/UMBILICAL ARTERIES: ***MEDIAL UMBILICAL LIGAMENTS.
3/ DUCTUS ARTERIOSUS: ***LIGAMENTUM ARTERIOSUM
4/DUCTUS VEINOSUS: ***LIGAMENTUM VENOSUM .
5/FORAMEN OVALE: ***FOSSA OVALIS
6/ALLANTOIS: ***URACHUS.
THYMUS:
SITE OF T CELL MATURATION .
FROM EPITHELIUM OF 3RD AND MAYBE 4TH
BRANCHIAL POUCHES.
LYMPHOCYTES OF MESENCHYMAL ORIGIN .
CORTEX IS DENSE WITH IMMATURE T CELLS,
MEDULLA IS PALE WITH MATURE T CELLS AND
EPITHELIAL RETICULAR CELLS.
TONGUE
DEVELOPMENT:
1st and 2nd branchial arches form
anterior 2/3 [thus pain via CN V3,taste via CN VII]
3RD AND 4TH ARCHES FORM POSTERIOR 1/3
[THUS PAIN AND TASTE MAINLY VIA CN IX ,EXTREME POSTERIOR VIA CN X]
MOTOR INNERVATION IS VIA CN XII
TASTE VII,IX,X
MOTOR XII
PAIN V3
DIAPHRAGM
EMBRYOLOGY:
DIAPHRAGM IS DERIVED FROM:
***SEPTUM TRANSVERSUM
***PLEUROPERITONEAL FOLDS
***DORSAL MESENTERY OF ESOPHAGUS
***BODY WALL.
***CYST : SPHERICAL EPITHELIUM LINED
CAVITY.
***PSEUDOCYST IS A SPHERICAL CAVITY
WITHOUT EPITHELIUM LINING .
***SINUS IS A BLIND -ENDING DUCT OR
SPACE OPENING EXTERNALLY OR INTERNALLY .
***FISTULA IS A PATENT [ABNORMAL] CANAL
WITH OPENING AT BOTH ENDS.
***ATRESIA IS A CLOSURE OF A NORMAL
BODY OPENING OR TUBULAR ORGAN.
***MECKEL'S DIVERTICULUM :
REMNANT OF THE
VITELLINE DUCT.
MAY CONTAIN
ECTOPIC ACID SECRETING GASTRIC MUCOSA AND/OR PANCREATIC TISSUE.
2 INCHES LONG
2 FEET FROM END OF SMALL INTESTINE
2% OF POPULATION
COMMONLY PRESENTS IN FIRST 2 YEARS OF LIFE.
MAY HAVE 2 TYPES OF EPITHELIA.
***AMNIOTIC FLUID
ABNORMALITIES:
POLYHYDRAMNIOS
: INDICATIVE OF ESOPHAGEAL /DUODENAL ATRESIA
OLIGOHYDRAMNIOS
: INDICATIVE
OF RENAL AGENESIS.
GENITAL DUCTS:
MESONEPHRIC
DUCT: DEVELOPS INTO *** EPIDIDYMIS
***DUCTUS
DEFERENS
***EJACULATORY
DUCT
***SEMINAL
VESICLES
PARAMESONEPHRIC
DUCT: " " " : ***FALLOPIAN
TUBE
***PART
OF VAGINA
MULLERIAN INHIBITING SUBSTANCE SECRETED
BY TESTES SUPPRESSES DEVELOPMENT OF
PARAMESONEPHRIC DUCTS.
++++MALE /FEMALE GENITAL HOMOLOGUES:
CORPUS SPONGIOSUM =VESTIBULAR BULBS
BULBOURETHRAL GLANDS [OF COWPER]
=GREATER VESTIBULAR GLANDS [OF BARTHOLIN]
PROSTATE GLAND =URETHRAL AND
PARAURETHRAL GLANDS [OF SKENE ]
GLANS PENIS = GLANS CLITORIS
+++
SPERM DEVELOPMENT :
SPERMATOGONIA--->1 SPERMATOCYTE
--->2 SPERMATOCYTE--->
SPERMATID--->[SPERMIOGENESIS]---->SPERMATOZA.
FULL DEVELOPMENT TAKES TWO MONTHS [61
DAYS]
DERIVATION
OF SPERM PARTS:
ACROSOME IS DERIVED FROM THE GOLGI
APPARATUS
MIDDLE PIECE [NECK] FROM MITOCHONDRIA
FLAGELLUM [TAIL] FROM ONE OF THE
CENTRIOLES
CHONDROCYTES DIFFERENTIATE FROM :
MESENCHYME
CHONDROCYTES SECRETE : +++COLLAGEN
+++CARTILAGE
PROTEOGLYCAN
+++HYALURONIC
ACID
+++GLYCOPROTEIN
SKELETAL MUSCLES AND CONDIA MUSCLE
CELLS:
+++
DERIVED FROM MESENCHYM
+++PRODUCTING
ACTIN
MYOSIN
TROPONIN
TROPOMYOSINE
a-actinin
neuroblast: neuron
glioblasts: glial cells
THE THREE PRIMARY GERM LAYERS
[GASTRULATION]:
+++ECTODERM
+++MESODERM
+++ENDODERM
FLEXION AND GROWTH OF THE AMNION ==>
TUBULAR STRUCTURE ===>BASIC VERTEBRA [BODY PLAN]
THE CV SYSTEM IS THE FIRST ORGAN SYSTEM
TO BECOME FUNCTIONAL IN THE EMBRYO .