Exam 3 Flashcards by Kole Hale

Compare the specific structures that Tbx4 and Tbx5 are responsible for initiating the development of.

Tbx4: initiator of future hindlimb development

Tbx5: initiator of future forelimb development

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Where does Rathke’s pouch originate? what adult structure does it become?

It originates at the roof of the mouth (called the stomodeum at the time it forms) and becomes the Anterior Pituitary Gland in adulthood

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Name the duct that temporarily connects the thyroid to the pharynx during development. What Adult structure on the tongue does this structure become?

The Thyroglossal duct, which becomes the Foramen Cecum on the tongue of an Adult

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What embryological tissue do the nephrons form from?

the metanephrogenic blastemata

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For males, state the embryonic tissue that will become the seminiferous tubules. What does this become in females?

Sex cords

Nothing. In Females, both the sex cords and rete cords will degenerate while the mullerian duct forms the ovaries.

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In limb development, expression of ___ and ____ fix the Anterior and Posterior axis respectively.

Gli3 = anterior

Hand 2 = posterior

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Migrating pre-muscle cells express ____ and _____.

Pax3

N-cadherin

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____ is expressed by the CT associated with the muscle masses of developing limbs.

Tcf-4

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Differentiation of pre muscle cells into muscle within the limb bud depends of ___, which is expressed by the limb bud ectoderm

Wnt-6

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What is the function of Wnt-7 in the developing limb bud?

The overlying limb bud ectoderm secretes it in order to restrict cartilage formation to the central core of the limb bud.

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Where in a developing embryo can one find Eng-1 (Engrailed-1) and Radical Fringe?

Eng-1: in the Ventral ectoderm of the AER

Radical Fringe: in the Dorsal ectoderm of the AER

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State the 3 migratory pathways that neural crest cells use in order from earliest to last (to migrate)

Ventral / Sympathoadrenal path (first emigrating)
Ventrolateral path (2nd emigrating)
Dorsolateral path (Last emigrating)

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For the 1st, 2nd, and 3rd pharyngeal arches, state the rhombomere(s) that the neural crests in the arch migrate from. Which of these requires no Hox, Hox2, and Hox3?

Pharyngeal Arch 1: neural crest cells from R1 and R2
Does not require Hox influence

Pharyngeal Arch 2: neural crest cells from R4
Requires Hoxa2 (to keep it from becoming the 1st arch)

Pharyngeal Arch 3: neural crest cells from R6 and R7
Requires Hox3

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What do most neural crest cells from somite levels 1-3 form?

What about neural crest cells from somite levels 1-3 + 4-7?

From somite levels 1-3: Cardiac neural crest

neural crest cells from somite levels 1-3 + 4-7: Vagal crest (provides parasympathetic innervation for the digestive tract)

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What roles do Slit-2 and robo play in the development of the vagal crest?

Slit-2 is expressed in the mesentery near the gut and serves to prevent neurons from entering area by interacting with Robo (the receptor for slit-2 that prevents axon growth in Slit-2 areas)

Trunk neural crest cells maintain their Robo and therefore respond to Slit-2 in the mesentery (this blocks them)

The vagal neural crest cells, however, do not express robo and can therefore invade and innervate the gut wall (enteric system)

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The following are symptoms of which neurocristopathy?

Colomba, Heart disease, Atresia of nasal choanae, retardation of development, genital hypoplasia in males, and anomalies of the ear.

Autosomal dominant, caused by mutation of the CHD7 gene on chromosome 8.

CHARGE

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In the developing eye, state what axis is determined by the following actions.

Ephrin gradients (Notch gene expression ensures that this process does not occur too early)

Antagonistic actions of Shh and BMP, along with Ventrotropin, Tbx-5, Pax2 and Vax2.

Which of these Axes forms first?

Ephrin gradients (Notch gene expression ensures that this process does not occur too early) = Nasotemporal (anterior-posterior axis)
This axis is fixed 1st

Antagonistic actions of Shh and BMP, along with Ventrotropin, Tbx-5, Pax2 and Vax2 = Dorsoventral axis
This axis is fixed 2nd

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The patterning of all pharyngeal pouches, besides the 1st, are heavily dependent on Retinoic Acid. What substance determines the patterning of the 1st pharyngeal arch?

Otx-2

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True or False:

Pharyngeal arch patterning is dependent on the neural crest. explain.

False

It is dependent on Retinoic acid and Otx-2 (1st arch only, all others are retinoic acid)

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The subdivision of the 1st arch into the upper and lower jaw primordia is dependent on what substance?

Endothelin-1 (this splits the 1st arch into maxillary and mandibular divisions)

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The bulk of meckel’s cartilage becomes the mandible, but it also gives rise to the Articular and Quadrate cartilages. What adult bones form from these?

Articular: becomes the Malleus

Quadrate: becomes the Incus

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Explain the relationship between the Optic Stalk, Optic vesicle, Choroid Fissure, and Lens Vesicle.

The Optic stalk forms first (basically just a balloon shaped blob the protrudes from the forebrain)

The Optic vesicle is the cavity inside of the Optic Stalk that is nearest to the Surface ectoderm (air in the balloon)

The Lens vesicle forms from the lens placode (ectoderm closest to the Optic vesicle) via invagination of the ectoderm that is “pinched off” to sit anterior to the Optic Vesicle

The Choroid Fissure is formed when the optic vesicle asymmetrically invaginates (folds like a taco) and ends up forming a cavity in the interior portion of the optic stalk
(this is where the hyaloid artery will reside)

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Describe how Pax6, Pax2 and Shh interact when forming the retina itself and the axons of the ganglion cells from the retina.

Pax6 expression in the distal optic stalk causes the formation of the retina

Pax2 expression in the proximal optic stalk causes the formation of the axons of the axons of the ganglion cells from the retina

High concentrations of Shh decreases Pax6 expression and allows Pax2 expression
(so there is a low concentration of Shh in the distal optic stalk and high concentration of Shh in the proximal optic stalk)

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State the 3 substrates for migrating neural crest cells that can be successfully navigated if the neural crest cell migration is mediated by integrins.

Fibronectin

Laminin

Type IV collagen

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What happens to neural crest cells if they are exposed to glial cell growth factor? What if they are exposed to BMP2 or BMP4?

It suppresses their tendency to develop into neurons and causes them to become Schwann cells instead BMP2/BMP4 causes them to differentiate into autonomic neurons

What condition is described here? this is normally caused by a lack of what structure developing properly? Absences of an eye caused by a mutation in RAX

Anophthalmos: absences of an eye caused by a mutation in RAX Normally attributed to lack of formation of the optic vesicle

What is the Condition that is described here? What are 2 potential causes for this? smaller than normal eyeballs

Microphthalamos: smaller than normal eyeballs Caused by a variety of genetic defects OR intrauterine infections (ex. Rubella syndrome commonly causes this)

What is the condition described here? Briefly describe it's presentation. Nonclosure of the choroid fissure past the 6th/7th week of development

Coloboma: nonclosure of the choroid fissure past the 6th/7th week of development The colomba marks the position of the embryonic choroid fissure (usually @ 5 oclock position on the right eye and @ 7 oclock position in the left eye)

What is the condition described here? A deficiency is what type of signalling can cause this? A single eye or what appears to be 2 fused eyes that is often accompanied by a proboscis formed nearby.

Cyclopia, which can be caused by a deficiency of Shh signalling (which in turn decreases the amount of available forebrain tissue with which to form this area of the fetus)

Mesenchymal cells produce ___ which inhibits FGF-10 and Shh in order to promote the synthesis of extracellular matrix molecules such as fibronectin, and collagen types I, III, and IV.

TGFbeta1

What stage of tooth development is described below? C-shaped bands of oral ectoderm overlying neural crest mesenchyme

Dental Lamina

What stage of tooth development is described below? Epithelial downgrowth overlying neural crest mesenchyme and marking the position of a single tooth

Tooth Bud

What stage of tooth development is described below? Inverted cup-shaped layer of ectoderm (ameloblast layer) capped by stellate reticulum and covering a mass of mesenchyme (aka the dental papilla)

Cap Stage

What stage of tooth development is described below? A condensation of mesenchymal cells around the developing tooth which will form the cementum and periodontal ligament

Dental Sac

Name the stages of tooth development that include the following action. The first appearance of the Single enamel knot The single enamel knot undergoes apoptosis and begins to form the 2 secondary enamel knots at the site of the future molar cusps.

The first appearance of the Single enamel knot = Cap Stage The single enamel knot undergoes apoptosis and begins to form the 2 secondary enamel knots at the site of the future molar cusps = Bell Stage

State the 5 stages of tooth development in chronological order

1. Dental Lamina 2. Tooth bud 3. Cap stage 4. Bell stage 5. Dental sac "Dentist's Teeth Can Bite Down"

Define Hypodontia

Hypodontia: congenital absence of teeth Caused by mutation in the EDA gene, which encodes ectodysplasin

Define Hyperdontia

Hyperdontia: excess number of teeth caused by gain of function mutations in the TRPS 1 gene (commonly seen in pt with Cleidocranial dysplasia AND/OR Trichorhinophalangeal syndrome)

Define Microdontia

Microdontia: abnormally small teeth most commonly caused by mutation of the MSX1 gene (severe cases in pt's with microcephalic osteodysplastic primordial dwarfism, a growth retardation condition)

Define Amelogenesis imperfecta

Amelogenesis Imperfecta: a group of disorders that causes abnormal development/amount of enamel that often leads to severe cavities.

Define Macrodontia and state the syndrome it commonly occurs with.

Macrodontia: abnormally large teeth commonly occurs in KBG syndrome pt's (intellectual disability and skeletal malformations)

Define Enamel Fluorosis and how it occurs.

Enamel Fluorosis: ranges from white spots/lines in enamel to enamel hypoplasia caused by excessive fluoride consumption during tooth formation

The following are derivatives of which pharyngeal pouch? State what signalling molecule in high concentration causes the development of each of these structures. Inferior Parathyroids Thymus

3rd pharyngeal pouch Inferior Parathyroids: from high concentration of Shh Thymus: from high concentration of BMP-4

The following are derivatives of which pharyngeal pouch? Tympanic cavity of Middle ear Auditory Tube

1st pharyngeal pouch

The following are derivatives of which pharyngeal pouch? Fossa for palatine tonsils

2nd pharyngeal pouch

The following are derivatives of which pharyngeal pouch? ``` Superior parathyroids Post Branchial (ultimobranchial) body (which become incorporated into the thyroid as parafollicular (C) cells which secrete calcitonin) ```

4th pharyngeal pouch

What is the function of Sprouty?

it reduces the sensitivity of the anterior mesonephric duct to GDNF This allows the Ureteric bud outgrowth to occur from the mesonephric blastema

What is the function of Gremlin?

Gremlin: inhibits the inhibitory action of BMP, allowing the ureteric bud to form (works together with Sprouty to allow the ureteric bud to form)

Explain the interaction between Pax-2, Pax-8, and Lim-1.

Lim-1 signals for Pax-2 and Pax-8 to begin the formation of the pronephros by aggregating the intermediate mesoderm

Compare what occurs with the mesonephric and mullerian ducts depending on the sex of a fetus.

The production of testosterone in males will cause the retention of the mesonephric ducts Developing sertoli cells in the sex cords will secrete anti mullerian factor to degenerate the mullerian ducts In Females, nothing is produced to affect either duct so the Mullerian ducts are retained and the mesonephric ducts degenerate

For males and females, state what will be formed by the genital tubercle.

In males: it becomes the glans penis In Females: it becomes the Clitoris

For males and females, state what will be formed by the Genital Folds.

In males: it fuses and becomes the shaft of the penis In females: it will remain unfused and become the labia minora

The indifferent gonad consists of an outer cortex and an inner medulla. Describe where the male and female parts of this bipotential system are found in this indifferent gonad. Then state the adult structures that this will form in both sexes

Male parts are found in the inner medulla Give rise to the seminiferous tubules containing Sertoli cells and Interstitial cells Female parts are found in the outer cortex Give rise to the ovary

What is the layer that separates the medulla and cortex of the indifferent gonad?

the tunica albuginea | ends up on the external surface of the testes and is internalized in ovaries

Cyp26B1, Nanos, and decreased levels of RA leads to what? | Stra-8 and Increased levels of RA leads to what?

Mitotic arrest in Male gonads (until puberty) Meiosis begins in Female gonads

State what eventually develops from the 1st through 6th pairs of aortic arches.

1st and 2nd degenerate 3rd: forms internal and common carotid arteries (Common carotids are actually from Ventral Aortae, cranial to the 3rd arches) 4th: forms Aortic arch (humans only have the left, the right 4th becomes the Right subclavian artery) 5th: Degenerates 6th: becomes associated with the respiratory system (Ductus Arteriosus forms from the left one)

For what developmental process VEGF-A crucial for?

Vasculogenesis and Angiongenesis

What is the major producer of blood cells between week 6 through month 6? where does blood cell formation switch over to after month 6 and what controls this switch?

The liver At month 6, Fetal Adrenal gland cortisol triggers the bone marrow to be the main producer of blood cells for the baby

Compare the tissues the the Conus Arteriosus (proximal region of the bulbus cordis) and the Truncus Arteriosus (distal region of the bulbus cordis) are derived from

Conus Arteriosus: derived from the Secondary Heart Field Truncus Arteriosus: derived from the Neural Crest

In the bulbus cordis, what are the opposing truncoconal ridges responsible for?

They fuse together, separating the Ascending Aorta from the Pulmonary trunk in a "spiraling pattern"

The Septum Primum is associated with the ____ ______, while the Septum Secundum is associated with the _____ _____. Briefly describe how blood flows through these 2 foramen AND which one of them closes with the fusion of the septum primum with the endocardial cushion.

Foramen Primum Foramen ovale The Foramen Primum closes when the septum primum fuses with the endocardial cushion.

State the molecule that is responsible for the initial induction of the Septum Transversum. What about the Cardiac mesoderm?

Septum Transversum: BMP Cardiac Mesoderm: FGF

The Falciform ligament is a remnant of the Ventral ____.

Mesentery

Exam 3 Flashcards

(63 cards)