48 & 72 Hr Chick.pdf

48 HR CHICK  

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Head fold moves post. Heart twists upon itself Atrium and ventricle lies outside body Amniotic fold = head + lateral body fold Caudal fold- start of tail Subcaudal pocket- seps embryo from blastoderm Cephalization Ventral flexion- ant. Bending o Cranial flexure- midbrain o Cervical flexure- hindbrain & spinal cord junction Dextral torsion- ant. Twisting of entire head

 3 Fetal Membranes: 1) Amnion- inner ecto, outer somatic meso 2) Yolk sac- endo, splanch meso; left 2-layer w/ blood vessels 3) Chorion- outer ecto, inner somatic meso; right 2-layer  3 irregular white lines radiating from heart towards auditory vesicle: 1) 1st branchial groove 2) 2nd branchial grove 3) 3rd branchial groove THROUGH MESENCEPHALON Mesencephalon- first to be observed, cranial flexure allows several divisions of the brain to be seen Isthmus- partially seps mesen from meten Myelencephalon- thin roof of brain opposite mesen Mesenchyme- loose tissue bet. Brain and epidermis Extraembryonic Coelom- between fetal mems, bounded by somatic meso THROUGH DIENCEPHALON Diencephalon- lower cavity when brain seps, replaces mesen Velum Transversum- depression of forebrain, demarcation of dien and telen Metencephalon- poorly defined, ant. limited by isthmus Myelencephalon- upper cavity w/ thin roof, forms post. Choroid plexus Semilunar Ganglion- Trigeminal nerve (5)/ Gasserian ganglion, embed in myelen 1) Mandibular branch 2) Maxillary branch- medial

3) Ophthalmic branch- lateral mesen Jugular Ganglion- Cranial nerve (10), from neural crest cells, fades within 4th branchial arcg Anterior Cardinal Vein- separates the heart, seps to: 1) Postcardinal vein (ant.)- extend as intersegmental vein which drain blood from somite, notochord, neural tube 2) Common cardinal vein (post.) Notochord- elongated mass of cells, seps to 2 then becomes 1 bc cranial flexure THROUGH AUDITORY VESICLE Otic vesicle- invag. Ectoderm, in older specimens, dorsal wall is forerunner endolymph duct Acoustico-facialis Ganglion- cranial nerve (7-8) cont w/3rd branchial arch, attach to auditory vesicle and ant cardinal vein Superior Ganglion- glossopharyngeal nerve (9), when auditory vesicle isn’t present, poorly circumcised, THROUGH OPTIC CUPS Optic Cup- invag. Optic vescicle 1) Inner sensory retina 2) Outer pigmented epith Lens Vescicle- invag. Ectoderm, sac-like inside optic cup Pharynx- triangular, 1st pharyngeal pouch is middle and arms, then invag. to form 1st branchial groove and 1st branchial/closing plate Preoral gut- ant. most of foregut, seps from pharynx by oral plate, fingerlike diverticulum, fate: disappears after oral plate ruptures Carotid Loop- extension of 1sr aortic arch, near ant. cardinal vein Internal carotid arteries- extend from carotid loop Dorsal aorta- beside notochord, above pharyngeal pouch 1st aortic arch- beneath pharyngeal pouch, located in mandibular process, from dorsal aorta will become aortic arches 1, 2, 3 then each pair will merge to become Ventral Aorta then extend to yolk sac as vitelline arteries Rathke’s Pouch- evag. Stomodeum, cudoibal epith, rudiment for ant. pituitary gland, vesicle bet. Infundibulum and pharynx, opening is stomodeum, fate: hypophysis Visceral Arches- between pharyngeal pouch, lateral walls thickened, filled with mesenchyme Mandibular Arch/ 1st visceral arch- ant. mesenchyme mass, fate: jaws, bears 1st aortic arch Maxillary Arch- beside Rathke’s pouch, ant to stomodeum Oral Plate- ecto & endo, seps stomodeum and pharynx Infundibulum- evag. Diencephalon, fate: post. Hypophysis

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THROUGH THYROID RUDIMENT/ 2ND AORTIC ARCH Thyroid rudiment- depression of pharynx floor between 1st and 2nd phar pouch 2nd aortic arch- contained in 2nd visceral arch/Hyoid arch; (note: arches post. to 2nd visceral arch is called branchial arches cause it bears gills in lower vert) Ventral Aorta- combines 1st, 2nd, 3rd aortic arches, connected to bulbous cordis THROUGH 3RD AORTIC ARCH Bulbus Cordis- seps from ventral aorta via endocardium & myocardium Dorsal Mesocardium- mesoderm stalk attach to dorsal wall coelom Nasal Placode- ectoderm, near telen Somites- near myelen 1) Dermatome- dark stain under ectoderm, fate: dermis 2) Myotome- light stain, fate; muscles 3) Sclerotome THROUGH ATRIUM AND VENTRICLE Spinal cord- replace myelen Descending aorta- fused dorsal aorta Intersegmented Arteries- blood vessel in interval from dorsal aorta to spinal cord Conus Arteriosus- right side, endo and myo far apart Atrium- left side, endo and myo close, fate: auricles Ventricle- looped chamber, connect conus & atrium Trabeculae- irregular projections of myocardium in ventricle wall Laryngotracheal Groove- depression of foregut, level at 4th phar pouch, fate: larynx, trachea, lung buds

Caudal liver rudiment- branch ventral to SV, both continuous to duodenum THROUGH ANT INTESTINAL PORTAL Ant. Intestinal Portal- opening of foregut to midgut Vitelline Veins/ Omphalomesenteric Veins- lie near AIP, from SV, left veins passes through yolk first Peritoneal Cavity- where internal organs are Mesonephric Ducts- near desc aorta THROUGH LATERAL AMNIOTIC FOLDS Lateral Amniotic Folds- made with somatopleure, elevated about to fuse, cont with LBW 1) Inner Amnion 2) Outer chorion Vitelline Blood vessels- in splanchnic mesoderm Mesonephric Tubule rudiments- undergo cavitation to form tubule of mesonephric kidneys (formed by delamination on nephtotome/ nephron cord), opening: nephrotome Vitelline Artery- dorsal aorta > aortic arch 1-4 > ventral aorta > vitelline artery THROUGH TAIL BUD Tail bud- mesenchyme cells covered by ecto Hindgut- w/ floor Allantoic rudiment- endoderm cavity below tail bud Caudal Instestinal Portal- opening of hindgut to yolk, where allantoic floor disappears

78 HR CHICK THROUGH SINUS VENOSUS Sinus Venosus- attached to foregut via dorsal mesocardium, attach to common cardinal vein/ duct of cuvier, extends as Vitelline veins Pleuropericardial membrane- mesenchyme enclose common cardinal vein, spes pleural from pericardial Lung buds- evag. Foregut Transverse Septum- seps pericardial and peritoneal cavity, mesenchyme enclose SV, connected with pleuroperi membrane, where cranial liver divert. isopt Cranial liver diverticulum- mall of cells dorsal SV, lies in transverse septum, when continuous with foregut there’s a duodenum

- Paired wing and lung buds not bounded  Cervical/Nuchal Flexure- first somites  Tail Flexure Metencephalon- roof fate: cerebellum, boundary bet myelen indistinct Myelencephalon- post. choroid plexus/ roof fate: medulla, ectoderm Neuromeres- (11) enlargements of meten, myelen wall Fore: 1-3 Mid: 4-5 Hind: 6-11 (10- auditory vesicle) Post. Choroid Plexus- vascularization

© Vanessa Manalo

Endolymphatic ducts- near myelen, thick walled oval structure before auditory vesicle Auditory Vesicle- 10th neuromere, 2 nerve fibers becomes cont with ganglia  Spinal Cord structures: Roof plate- mid-dorsal wall Floor plate- mid-ventral wall Sulcus limitans- lateral depression of central canal Alar plates- dorsolateral wings of spinal cord, bet SL and roof plate Basal plates- ventrolateral wings, bet SL and floor plate  Spinal Cord membranes: Marginal layer- outer layer, few nuclei Mantle layer- many nuclei Ependymal layer- innermost, mitosis Oculomotor Nerve (3)- innervate 4 pairs of extrinsic eye muscles, from neuroectodermal cells, appear as pair of streak in mesen floor Closing Plate/1st branchial plate- 2-layer from endo & ecto (phar pouch, furrow) Pharyngeal Furrow (4)- invag. phar pouch, ectoderm indentation Pharyngeal Pouch (4)- evag. Endoderm, 1st phar pouch/Hyomandibular pouch Hyoid Arch/2nd visceral arch- mesenchyme bet 1st and 2nd furrows Symphysis of lower jaw- 2 mandibular arch fuse 1st aortic arch- in mandibular process, 1st -3rd aortic arch > ventral aorta 2nd,3rd,4th aortic arches- dorsal aorta > 2nd -4th aortic arch > 24 branchial arch Internal Carotid artery- extension of dorsal aorta, in mesenchyme, broken into 2 segments by phar pouch Trachea- arises with lung buds Lung buds- expansion of laryngotracheal groove Esophagus- rounded part foregut, in splanchnic meso with lung bud Mediastinum- where lung buds and esophagus in embedded 1) Dorsal mesogaster 2) Ventral mesogaster/hepatogastric ligament Optic Fissure/ choroid fissure- invag. of optic cup & stalk Lens Vesicle- free from ectoderm > cornea epith- cover eye lens 1) Inner lens fiber 2) Outer lens epith

Optic Cup- mesenchyme cells outside form sclera and choroid Optic Stalk- cont w/ dien Ductus Venosus- embedded is liver diverticula Duodenum- appears when ant liver diverticulum becomes cont with foregut; dorsal mesentery- mesoduodenum, post mesentery- hepatoduodenal ligament Allantoic vein/ umbilical vein- lateral body wall, drains blood from allantois Lamina terminalis- ant. telen wall Olfactory Placode- near telen Olfacotry pit- invag. ecto, fate: external nares Wing buds- from somatopleaure, ectoderm thickened as apical ectodermal ridge Intersegmental arteries- cont w/ dorsal aorta Mesonephric ridge- fate: mesonephros Mesonephric duct/ Wolffian duct- near post cardinal vein Mesonephric tubules- fate: mesonephric kidneys Subcardinal vein- beneath kidneys Leg buds- level of PIP Tail bud- function: store N-wastes, respiration for embryo, undiff cells, remnants of hensen’s node and prim pit Allantois- from splanchnopleure, , connected to hindgut Chorio-allantoic membrane- function: respiration, absorb calcium in cell, below inner shell mem Yolk sac- function: digest yolk then transport to embryo via vitt veins, from splanchnopl that overgrows yolk Cloaca- cont w/ allantois and mesonephric ducts Cloaca Membrane- endo & ecto, anal opening when ruptures

© Vanessa Manalo