| From what structure does the Embryo Proper develop? | Embryonal Disc
(central part) |
| What structure connects the fetal membranes to the surrounding fetal membranes and placenta? | Umbilical chord |
| Name the 10 steps of the Development of the Body Form | 1) Cylindrical Body Formation; 2) Formation of the Chorion & Amnion; 3) Futher Development of the Nervous System; 4) Initial Development of the Cardio-Vascular System; 5) Further Development of the Digestive System; 6) Initial Development of the Urogenital System; 7) Further Development of the Trunk; 8) Further Development of the Head; 9) Formation of the Tail; 10) Formation of the Limbs |
| Embryonic Folding | Embryo changes shape from a flat trilaminar disc to a cylinder |
| Embryonic Folding Occurs in the _____ and _____ Planes. | Horizontal; Median |
| Two Lateral Body Folds is the result of _____ folding. | Horizontal |
| Embryonic folding in the median plane leads to the development of the _____ and _____ folds | Cranial; Caudal |
| What germ layer is responsible for the development of the GIT? | Endoderm |
| What structure ruptures at the end of the fourth week of development to form the mouth? | Oropharyngeal Membrane |
| What structure is formed at the connection between the Midgut and the Yolk Sac? | Vitelline Duct
(Narrow Tube) |
| What structure temporarily closes the hindgut at the caudal end? | Cloacal Membrane |
| The Cloacal membrane ruptures to form the _____ and _____ openings. | Urogenital; Anal |
| During embryonic folding what part of the embryo is the first to become cylindrical | Head |
| What body folds are involved in the formation of the head? | Ventral merging of the head Folds with the most cranial sections of the Lateral Folds |
| Cephalic Flexure | Ventral deflection of the head process
Caused by the the dorsal aspect of the head growing more rapidly than the ventral aspect |
| What body folds are involved in the formation of the tail bud? | Ventral merging of the Tail Folds with the most caudal sections of the Lateral Folds |
| Pre-enteron | Foregut |
| Metenteron | Hindgut |
| Mesenteron | Midgut |
| The _____ _____ assists in the advancement of the tail fold. | Sacral Flexure |
| The _____ _____ assists in the advancement of the head fold. | Cephalic Flexure |
| Name the 2 structures involved in the formation of the Foregut (Pre-enteron)? | Head Fold; Cephalic Flexure |
| Name the 2 structures involved in the formation of the Hindgut (Metenteron)? | Tail fold; Sacral Flexure |
| Where does the lateral body folds develop? | In the Somatopleure, on either side of the embryo |
| Name the 2 structures that are involved in the formation of the Midgut (Mesenteron)? | Lateral Body Folds
Dorsal portion of the Yolk Sac. |
| The _____ mesoderm of the four body folds (head, tail, 2x lateral) fuses with the _____ mesoderm to form the _____ _____. | Somatic
Splanchnic
Umbilical Chord |
| What structure separates the endo- and exocoelom? | Umbilical Chord |
| Somatic Mesoderm of the Umbilical Chord is surrounded by a layer of ectoderm that continues proximally with the _____ of the embryo, and distally with the _____. | Ectoderm
Trophoblast |
| Name the 4 structures that the early umbilical chord consists of. | Vitelline Duct
Blood Vessels
Splanchnic Mesoderm
Somatic Mesoderm |
| Describe formation of the Ventral Body Wall Cranial to the Umbilical Chord. | Merging of the head fold and two lateral body folds ventral to the primitive gut.
After fusion the ventral body wall consists of ectodermal and somatic mesodermal layers. |
| Describe formation of the Ventral Body Wall caudal to the Umbilical Chord. | Merging of the tail fold and two lateral body folds ventral to the primitive gut.
After fusion the ventral body wall consists of ectodermal and somatic mesodermal layers. |
| From what structure does the chorioamniotic folds develop? | Somatopleure |
| Name the structure that runs continuously with the outer lamina of the chorioamniotic folds? | Trophoblast |
| Name the structure that runs continuously with the inner lamina of the chorioamniotic folds? | Somatopleure surrounding the umbilical chord |
| The prosencephalon develops to form the two cerebral hemispheres of the _____, and the centrally placed diencephalon | Telencephalon; Diencephalon |
| Name the ventricles of the Prosencephalon | Lateral ventricles of the Cerebral Hemispheres and the Third Ventricle of the DIencephalon |
| Name the structure that connects the third ventricle to the fourth ventricle | Mesencephalic Aqueduct |
| Name the structures that make up the Rhombencephalon (including their substructures) | Metencephalon (Cerebellum and Pons)
Myelencephalon (Medulla Oblongata) |
| Name the Ventricle of the Rhombencephalon | Fourth Ventricle |
| When does the embryo obtain its C-shape? | When the four flexures are maximally developed.
Approximately day 20 |
| Name the 4 flexures. | Cephalic
Cervical
Dorsal
Sacral |
| From what coelom does the Pleural and Pericardial cavaties develop? | Pleuropericardial Coelom |
| Describe the formation of the pleuropericardial coelom. | Internal delamination of the mesoderm peripheral to the developing head region. |
| What structure prevents the pleuropericardial coelom of expanding? | Solid wall of unsplit metoderm (connecting the soma- and splanchnopleure) |
| The pleuropericardial coelom communicates caudally with the _____. | Endocoelom |
| Name the structure from which the heart develops. | Cardiogenic Plate
(delaminated mesoderm) |
| The unsplit mesodermal plate just in front of the cardiogenic plate will later form the _____ _____. | Septum transversum |
| The transverse septum lies caudo-dorsal to the apex of the _____ _____, caudal to the developing _____ and ventral to the _____. | Pleuropericardial coelom
Heart
Pre-enteron (Foregut) |
| The liver will be formed as an evagination of the _____ and will grow into the _____ _____. | Duodenum
Septum Transversum |
| The Septum Transversum will form part of the _____ to which the _____ will remain attached by ligaments | Diaphragm
Liver |
| What structure is responsible for the "pot-belly" of the young embrio? | Heart |
| The _____ is initially the most prominent organ, but later the _____ becomes the more prominent. | Heart
Liver |
| A shallow cleft between the heart and liver bulges indicates the position of the future _____. | Diaphragm |
| What structure connects the primitive Mesenteron to the Yolk Sac? | Vitelline Duct |
| What structure forms the rostro-ventral border of the pre-enteron? | Oropharyngeal Membrane
(Formerly the prechordal plate) |
| The stomodeum is formed ventral to the _____, it is bounded rostrally by the _____ _____, laterally by the _____ primordia, and caudally by the _____ bulge. | Oropharyngeal Membrane
Head Process
Jaw
Cardiac |
| The oropharyngeal membrane later ruptures and this establishes communication between the _____ cavity and _____. | Oral
Pharynx |
| The _____ ______ forms the caudo-ventral border of the metenteron. | Cloacal Membrane |
| After the cloacal membrane ruptures, the cloacal opening is devided horizontally by the caudally directed _____ septum to form the _____ (dorsally) and the _____ opening (ventrally). | urorectal
anus
urogenital |
| How is the proctodeum formed? | Anal hillocks develop on either side of the anus forming the anal canal |
| Between what 2 structures does the Labio-scrotal swellings and Genital Tubercule (Phallus) develop? | Urogenital Opening
Umbilicus |
| The labio-scrotal swellings become the _____ (male) or _____ female. | Scrotum
Labia |
| The Phallus (Genital Tubercule) become the _____ (male) or _____ female. | Penis
Clitoris |
| The allantois (one of the fetal membranes) develops as a ventral outgrowth of the _____; it extends through the _____ _____(where it is surrounded by splanchnic mesoderm) and expands into the _____. | Metenteron
Umbilical Chord
Exocoelom |
| Name the structure that connects the distal saccular portion of the allantois to the metenteron? | Allantoic Duct |
| From what structure does the urinary bladder develop? | Proximal portion of the allantoic duct (Urachus) |
| What structure connects the embryo to the fetal membranes? | Umbilical Cord |
| Name the structures that the umbilical cord consists of. | Vitelline Duct
Paired Vitelline arteries and veins (for as long as the yolk sac persists)
Allantoic Duct
Paired Umbilical arteries and veins |
| The bones of the cranium and the surrounding connective tissues are formed from head _____. | Mesoderm |
| The facial skeleton, which supports the rostral _____ and _____ _____, originates from _____ _____ _____ with contributions from the _____ _____. | Pre-enteron
Respiratory tract
Paryngeal arch Mesoderm
Neural Crests |
| What structure forms the future optic nerve? | Optic Stalk |
| How long after birth does the eyes of carnivores remain closed? | 8-12 days |
| The eyes are initially directed _____; after formation of the face, they are directed more _____ in species with well-developed binocular vision (e.g. carnivores). | Laterally
Medially |
| What structure gives rise to the adenohypophysis? | Rathke's Pouch |
| Where does Rathke's pouch develop? | In the roof of the stomodeum, just rostral to the oropharyngeal membrane. It grows to-wards the mid-brain where it will give rise to the adenohypophysis. |
| Seessel's pouch develops in the roof of the _____, just caudal to the _____ _____. | Pharynx
Oropharyngeal membrane |
| Rupture of the oropharyngeal membrane establishes communication between the _____ _____ and _____. | Oral cavity
Pharynx |
| Name the structure responsible for the development of the pharyngeal pouches. | Pre-enteron |
| The ectoderm overlying each pharyngeal pouch invaginates to form a (a). Each (a) is separated from its corresponding pouch by a (b), a thin sheet consisting of ectoderm and endoderm in contact with one another. | a) Pharyngeal groove
b) Pharyngeal membrane |
| Rostral to the first pharyngeal groove and between successive pharyngeal grooves, the mesoderm proliferates to form dorso-ventrally orientated, outward-bulging structures known as _____ _____. | Pharyngeal arches |
| In theory, _____ pharyngeal arches are formed; however, only the first _____ are clearly distinguishable. | 6
3 |
| Name the pharyngeal pouch that never reaches the ectoderm. | Pharyngeal Pouch IV |
| Name the 3 tissues that are developed from each pharyngeal arch. | Cartilage
Blood vessel (aortic arch)
Muscle |
| The aortic arches are also numbered from rostral to caudal; they connect the ventrally situated _____ _____ (cranially directed from the heart) to the two dorsal _____. | Truncus arteriosus
Aortae |
| Name the largest pharyngeal arch. | Pharyngeal Arch I |
| Pharyngeal Arch I comprises a short _____ prominence (rostrally) and a longer _____ prominence (caudally). The groove between the two prominences will eventually form the _____ __ __ _____. | maxillary
mandibular
angle of the mouth |
| Name the structure that separates the maxillary prominence from the from the frontonasal prominence. | Nasolacrimal groove |
| The nasal _____, the future nostril, invaginates to form the nasal _____; continued development of the nasal pit will form the nasal _____. | placode
pit
cavity |
| What structure allows the nostril to communicate with the stomodeum? | Nasomaxillary groove |
| The nostril is bordered by _____ and _____ nasal prominences that develop from the rostral part of the frontonasal prominence. | medial and lateral |
| The fusion of the medial nasal prominences also forms the median (central) portion of the upper lip and gum; in the dog and sheep, the line of fusion is clearly visible as a vertical groove, the _____, running between the nostrils and dividing the upper lip in half. | philtrum |
| Defective fusion of the medial nasal prominences is seen as a central _____. | harelip |
| The maxillary prominence gives rise to a medially directed (a). The left and right (a)s fuse with each other and with the (b). | a) palatine process
b) nasal septum |
| What structure separates the oral and nasal cavities? | Palatine Process |
| Defective fusion of what structure leads to the formation of a cleft palate? | Palatine Processes |
| Each maxillary prominence fuses with the medial nasal prominence and eliminates the _____ _____ and forms the _____ portion of the upper lip and gum. | nasomaxillary groove
lateral |
| Defective fusion of the maxillary prominence with the medial nassal prominence causes the development of a lateral _____; this condition sometimes occurs bilaterally | harelip |
| Each maxillary prominence fuses with the lateral nasal prominence and forms the ventro-lateral quadrant of the _____. Fusion causes invagination of the ectodermal cells forming the _____ _____. | nostril
nasolacrimal groove |
| Nasolacrimal groove becomes hollow and forms the _____ _____, which runs from the medial angle of the _____ to the ventral part of the _____ _____. | nasolacrimal duct
eye
nasal cavity |
| The primordium of the inner ear, the _____ _____, develops from an ectodermal thickening dorso-caudal to the first _____ _____. | otic placode
pharyngeal groove |
| The otic placode invaginates to form the (a). The (a) separates from the ectoderm to form the (b) which later migrates deeper to assume its correct position opposite the (c). | a) otic cup
b) otic vesicle (or otocyst)
c) middle ear |
| The auricle, the cartilaginous part of the external ear, is formed by parts of the first and second _____ _____. | Pharyngeal arches |
| What structure forms the external auditory meatus? | Pharyngeal groove I |
| What structure forms the middle ear? | Pharyngeal pouch I |
| What structure forms the tympanic membrane? | Pharyngeal membrane I |
| What structure forms the auditory ossicles? | Cartilages of the first and second pharyngeal arches |
| What structure maintains the communication between the Pharyngeal Pouch I and the pharynx? | Eustachian tube
(auditory tube) |
| The end bud is formed by the retreating _____ _____ when it reaches the caudal end of the _____ _____. | primitive node
primitive streak |
| Name the structures that will differentiate to form the tissues of the tail. | notochord
paraxial mesoderm
neural tube |
| The tail bud also contains the tail gut, a dorso-caudal evagination of the _____; however, this structure soon completely disappears. | metenteron |
| Name the 2 structures from which the caudal vertebrae develop? | notochord and mesodermal somites |
| From what structure does the somites develop? | Paraxial Mesoderm |
| Besides the vertebrae, name the other tissues that the somites give rise to. | Caudal muscles
Fasciae
Ligaments |
| The caudal neural tube diminishes in size and, in the adult animal, is seen only as the _____ _____. | Filum terminale |
| The _____ aspect of the tail develops more rapidly than the _____ aspect and this causes ventral flexion of the tail; the distal end of the tail usually lies to the _____ of the body. | dorsal
ventral
left |
| From what structure does the limbs develop? | Wolffian ridges |
| The _____ limbs develop from the cranial portions of the Wolffian ridges, while the _____ limbs develop from the caudal portions; the ridges' _____ portions soon disappear. | thoracic
pelvic
middle |
| The thoracic limb buds form just dorsal to the _____ and are visible at an early age (day 17-18 in the pig); the pelvic limb buds form in the region of the _____, but at a slightly later stage.
The limb buds initially consist of dense mesoderm covered by ectoderm. | heart
sacrum |
| In man, all five digits develop fully; in the carnivores, digit _____ is reduced or absent. | I |
| In man, all five digits develop fully; In the pig and ruminants, digits _____ and _____ are reduced and digit _____ is absent. | II
V
I |
| In man, all five digits develop fully; while in the horse, only digit _____ develops fully. | III |
| The heart develops in the _____. | Pleuropericardial Coelom |
| True or False? The chrorioamniotic folds form a continuous groove around the embryo proper. | False
The body folds form a continuous groove around the embryo proper. |
| True or False? In the embryo the tail bud contains the tail gut. | True |
| The mandibular arch is pharyngeal arch number: | I |
| The lens develops from the: | Ectoderm |
| The grey matter (cell bodies) originates from the: | Mantle layer |
| True or False? Seesels’s pouch is the origin of the adenohypophysis. | False
Rathke's pouch is the origin of the adenohypophysis. |
