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 .