48 Hr Reviewer

[EMRBYO LAB]

hr chick reviewer

WHOLE MOUNT    

Cranial half : covered with head fold of amnion Caudal part : does not show such covering Subcaudal pocket – separates from the underlying blastoderm Cephalization at the anterior portion (brain) → ventral flexion (bending) and dextral torsion

(twisting)  Heart becomes elongated (twisted itself)  3 FETAL MEMBRANES o amnion – encircles the anterior portion of embryo ; inner ectoderm & outer somatic mesoderm o yolk sac – double-membraned on the left side; w/ blood vessels; endoderm & splanchnic mesoderm o chorion – double-layered on the right side; close to amnion; outer ectoderm & inner somatic mesoderm  3 IRREGULAR WHITE LINES SEEN FROM HEART TOWARDS AUDITORY VESICLE o 1st branchial groove o 2nd branchial groove o 3rd branchial groove  ARCHES o 1st visceral arch – above 1st branchial groove o 2nd visceral arch – between 1st & 2nd branchial groove o 3rd visceral arch – between 2nd and 3rd branchial groove  1st visceral arch processes: o Maxillary process – ant. to stomodeum o Mandibular process – post. to stomodeum  Myelencephalon – brain region where ganglia are associated  Pharyngeal/ hyomandibular pouch & branchial groove – contribute to the formation of 1 st    

branchial plate Rathke’s pouch & infundibulum – 2 structures that forms the hypophysis 3 pharyngeal pouch 3 aortic arches 3 visceral arches Structure

Description TRANSVERSE SECTION SEC. THRU MESENCEPHALON

mesencephalon

isthmus

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Oval shaped 1st cavity of the brain to be observed Shows frontal section due to cranial flexure Constriction Partially separates the mesencephalon from hindbrain

Fate

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hr chick reviewer

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Metencephalon

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Thin roof at the opposite end of mesencephalon Underlined portion between myelencephalon and isthmus Loose connective tissue between brain and epidermis Amnion, chorion, & yolk sac Space bounded by mesoderm, between the chorion, yolk sac, amnion SEC THRU DIENCEPHALON Lower cavity when the brain separates Replaces the position of mesencephalon Depression found in the dorsal wall of the forebrain Demarcation between diencephalon & telencephalon Delimited by the isthmus at this section

Myelencephalon

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Upper, larger cavity of all with thin roofs

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Ganglion of trigeminal (V) cranial nerve Dark cells closer to myelencephalon Ganglion of X cranial nerve Lateral to myelencephalon Above the anterior cardinal vein

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Space lined by thin wall along each side of myelencephalon

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Small, elongated mass of vacuolated cells Between the myelencephalon & diencephalon Separates into 2 (due to cranial flexure) SEC THRU OTIC VESICLE Paired vesicle each side of the myelencephalon Invagination of ectoderm

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Pair on the ventro-lateral side of otic vesicle

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Ganglia of VII & VIII cranial nerves Cells close (or attached) to otic vesicle & ant. cardinal vein Lateral to myelencephalon Ganglion of trigeminal (V) cranial nerve

myelencephalon metencephalon mesenchyme fetal membranes extraembryonic coelom diencephalon

velum transversum

Semilunar ganglion Jugular ganglion Anterior cardinal vein syn: precardinal vein

notochord

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 Otic vesicle syn: auditory vesicle otocyst Anterior cardinal vein Acoustic-fascialis ganglion Semilunar ganglion

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Posterior choroid plexus

Disintegrate

Endolymphatic duct

[EMRBYO LAB]

hr chick reviewer

Superior ganglion

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   Optic cup 

 Lens vesicle Optic stalk

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pharynx

  Pre-oral gut 

Carotid loop Internal carotid arteries Dorsal aorta 1st aortic arch Mandibular arch

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Dark cells attached to myelencephalon Ganglion of glossopharyngeal (IX) nerve Cells on both sides of myelencephalon Observed when otic vesicle is no longer present or immediately posterior to the auditory vesicles SEC TRHU OPTIC CUPS Double-walled structure on each side of diencephalon Derived from invagination of optic vesicle Sensory retina – thicker, inner layer  Presumptive retina – inner layer of cup Pigmented retina – thinner, outer layer  Presumptive pigmented epithelium – outer layer of the cup Little sac-like cavity nestled w/in the optic cups Arises as an invagination of ectoderm Connects the optic cup with diencephalon Cavity (triangular shape) 1st pharyngeal pouch (arms of triangle) – hyomandibular pouch  Invaginates to form 1st branchial groove  Double-layered formed is 1st branchial plate Anterior most part of the foregut Small circle or oval structure separated from the pharynx by oral plate Extends as a fingerlike diverticulum anterior to the future mouth Extensions of the 1st aortic arches Elongated spaces medial to ant. cardinal veins Paired vessels from the carotid loops to the optic cups Blood vessels on either side of notochord Lies above the 1st pharyngeal pouch

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Blood vessel beneath the 1st pharyngeal pouches

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Mesenchymal mass between stomodeum

Pigmented layer of retina

Becomes located at mandibular process then becomes continuous w/ ventral aorta

jaws

[EMRBYO LAB]

hr chick reviewer syn: 1st visceral arch

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Rathke’s pouch  Oral plate syn: pharyngeal membrane

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Bears the 1st aortic arch Small vesicle between infundibulum & pharynx Dorsal evagination of stomodeum Thin line (ectoderm & endoderm) separating stomodeum & pharynx

Evagination from diencephalon Will later evaginate post. lobe of hypophysis Diencephalon More elongated in this section Slit-like space where Rathke’s pouch opens Separates maxillary process & mandibular stomodeum process SEC THRU THYROID RUDIMENT & 2ND AORTIC ARCH Thyroid rudiment  Depression in the floor of the pharynx  Lies beneath the 2nd pharyngeal pouches  Contained within 2nd visceral arches (hyoid 2nd aortic arch arches)  Will later become continuous with ventral aorta nd 2 pharyngeal pouch  2nd outpocketing of pharynx  Blood vessel beneath the pharynx  Starts where the bases of 1st aortic arches meet Ventral aorta  2 layers in its wall indicates beginning of syn: aortic sac bulbus cordis  Connected anteriorly: aortic arches (1,2,3)  Connected posteriorly: bulbus cordis SEC THRU 3RD AORTIC ARCH  Large outpocketing of pharynx 3rd pharyngeal  Together with pharynx, laterally oriented oral pouches cavity  Beneath the 3rd pharyngeal pouch (not-so 3rd aortic arches developed)  Will later become continuous with ventral aorta  Between 2nd & 3rd pouches  Arches posterior to the hyoid arch = branchial 3rd visceral arch arches  1st heart cavity  Presence of endocardium & myocardium Bulbus cordis (differentiates it from ventral aorta)  Mesodermal stalk that attaches the stalk to Dorsal mesocardium the dorsal wall of coelom  Thickened skin ectoderm lateral to the Nasal placode telencephalon infundibulum

hypophysis

[EMRBYO LAB]

hr chick reviewer

1st somite dermatome myotome Anterior cardinal veins Spinal cord Descending aorta Dorsal intersegmented arteries

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Conus arteriosus

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Atrium

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Ventricle Laryngotracheal groove Future esophagus Cardinal veins

Sinus venosus Common cardinal vein

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Cell masses lying lateral to myelencephalon Darkly stained beneath the skin of ectoderm Lightly stained cell medial to dermatome Seprates into 2 vessels: postcardinal vein (dorsal) common cardinal vein (ventral)

SEC THRU ATRIUM AND VENTRICLE Replaces the myelencephalon Fused dorsal aortae Small blood vessels arising at intervals from dorsal aorta & extending dorsally bet spinal cord & somite Chamber of heart at the right side Endocardium & myocardium are widely separated Chamber at the left side Endocardium & myocardium are in close contact/ fused Large looped chamber of the heart Connects the conus and the atrium Deep V-shaped depression in the floor of the foregut Dorsal portion of the gut Paired precardinals Separates into 2 vessels: postcardinal vein (dorsal) common cardinal vein (ventral) SEC THRU SINUS VENOSUS Portion of the heart attached to the foregut by dorsal mesocardium

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To which sinus venosus is attached

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Mesenchyme enclosing the common cardinal vein (separates the pleural from pericardial)

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Slight evagination on the ventro-lateral portions of the foregut into pleural cavities

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Paired, lateral to the developing lung buds & continuous with pericardial cavity Mesenchyme surrounding the sinus venosus Connected with the pleuropericardial membrane

syn: duct of Cuvier

Pleuropericardial membranes Lung buds Pleural cavity Transverse septum

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Dermis of skin muscle

auricle

Larynx, trachea, & lung bud

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Cranial liver diverticulum

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Mass of cells on the dorsal side of sinus venosus lying in the transverse septum ventral to the foregut

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Branch/es on the ventral side of the cranial liver rudiment

syn: dorsal diverticulum

Caudal liver diverticulum syn: ventral diverticulum

duodenum Anterior intestinal portal Vitelline veins syn: omphalomesenteric vein Peritoneal cavity Paired mesonephric duct

Lateral amniotic folds Vitelline blood vessels

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Continuous with the foregut posterior to the cranial liver diverticulum SEC THRU ANTERIOR INTESTINAL PORTAL 

Opening of the foregut to the midgut

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Pair of blood vessels w/c are posterior extensions of sinus venosus  Lie on each side of anterior intestinal portal  Left then right veins pass out onto the yolk  Big space where internal organs are  Small tubules lateral to the descending aorta  Medial to mesonephtic tubules  Formed by delamination from the nephrogenic cord (nephrotome) SEC THRU LATERAL AMNIOTIC FOLDS  Elevated & about to fuse folds  Consist of somatopleure that forms inner amnion & outer chorion  Small blood vessel embedded within the splanchnic mesoderm

Paired dorsal aortae

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Big pair of blood vessel below the notochord

Mesonephric tubule rudiments

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Round cavity medial to mesonephric duct

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Opening of the mesonephric tubule to the coelom Posterior of dorsal aorta extending onto the yolk sac SEC THRU TAIL BUD Mass of mesenchymal cells at the caudal end Covered by skin ectoderm Posterior portion of gut where it acquires floor Endoderm lined cavity below tail bud Space where the floor of the allantoic rudiment disappears

Nephrostome Vitelline arteries

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 Tail bud Hindgut Allantoic rudiment Caudal intestinal portal

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[EMRBYO LAB]

hr chick reviewer

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Opening of the hindgut in the yolk