Final Flashcards
At what # cell stage of development do the round blastomeres begin to flatten?
At 8-cell stage, developing an inside-outside polarity that maximizes cell-to-cell contact among blastomeres.
What is the functional matrix theory of growth?
It states that there is innate growth potential in the long bones, but neither the cartilage of the mandibular condyle nor the nasal septum is a determinant of jaw growth (contradicts our text book which considers the nasal septum as a primary growth center, and that is what we will go with in this class). It says that neither bone nor cartilage is the determinant for growth of the craniofacial skeleton, and that means that the control would be in the adjacent soft tissue. It also says that growth of the face occurs as a response to functional needs, and neurotrophic influences, and is mediated by the soft tissue in which the jaws are embedded. So the soft tissue grows, and both bone and cartilage react to his form of epigenetic (indirect control). The theory says that stimuli emanating in the growing head and body (the functional matrix), directly or indirectly, function to turn on or off cellular organelle activity in genetic material. This concept is not intended to explain how the actual morphogenic process works, but rather describe what happens to achieve the complex combination of actions. Moss theorized that the major determinant of growth of the maxilla and the mandible is the enlargement of the nasal and oral cavities, which grow in response to functional needs (Moss is unsure how functional needs are transmitted to these tissues).
What is the purpose of Mitosis?
Before a cell can divide, it must replicate its DNA first so that each new daughter cell will receive a complete copy of the DNA.
What forms the nasal septum?
While the secondary palate is forming, ectoderm and mesoderm of the frontonasal process proliferate to form the nasal septum that grows down from the roof of the nasal cavity to fuse with the upper surface of the primary and secondary palates, divides the nasal cavity into two nasal passages.
What is a LeFort I fracture?
A horizontal fracture through the maxilla that passes through the septum medially, and these result in a mobile hard palate.
Which arteries does the six pharyngeal arch give rise to?
The ductus arterious and the definitive pulomonary arteries
What is interstitial growth?
Growth that occurs at all points within the tissue, and this involves growth of soft tissues that occurs by a combination of hyperplasia and hypertrophy.
What does the second arch cartilage, which originates from neural crest cells, give rise to?
Stapes, styloid process, styloid hyoid ligament, lesser horn of hyoid bone, upper rim of body of hyoid bone.
What happens during Anaphase of Mitosis?
Anaphase begins when the duplicated centromeres of each pair of sister chromatids separate, and the now-daughter chromosomes begin moving toward opposite poles of the cell due to the action of the spindle. Depending on where the centromere is located along the chromosome, a characteristic shape appears during chromosome movement. There are V and J shapes. J in the middle and V on edges. At the end of anaphase, a complete set of chromosomes has assembled at each pole.
During what stage does the enamel organ form?
Bell stage, and it forms from the dental lamina.
What percent of Down Syndrome cases are hereditary vs random?
1% hereditary, 99% random.
What kind of head and face abnormalities do down syndrome patients have?
Hypodontia, protrude tongue, brachycephaly, epicanthal folds, short hard palate, enlarged tongue, flat facial profile, hypoplasia of midface, high incidence of class III occlusion and open bites because of it.
How many amino acids does PTH consist of?
84 amino acids, and is secreted in response to hypocalcemia and hyperphosphatemia.
How does the growth of the mandible primarily take place?
It occurs by both endochondral proliferation at the condyle and by apposition and resorption of bone at the bony surfaces. It seems clear that the mandible is translated in space by growth of muscles and other adjacent soft tissues and that addition of new bone at the condyle is in response to these soft tissues changes.
What is DiGeorge syndrome?
It is caused by a deletion in the long (q) arm of chromosome 22. 22q11.2 deletion. And this deletion leads to hypoplasia of 3rd and 4th pouch derivatives.
What is Treacher Collins Syndrome?
A generalized lack of mesenchymal tissue in the lateral part of the face, a genetic disorder, about 1 in 50,000. Usually have very small cheek bones and micrognathia, cleft palate, eyes that slant downward, coloboma, normal intelligence. Patients are referred to specialist between 4 and 7 for surgery.
What does the intermaxillary suture contain when an individual is growing?
Cartilage. This allows us to move the palate with an expansion device up to the age of 9 and 10.
What are the four main functions of saliva?
- Buffering ability2. Provides a cleansing effect3. Has antibacterial action4. Maintenance of oral environment
During Meiosis I or II is the chromosomal number reduced from diploid 2n to haploid 1n?
During Meiosis I
Which artery does the second pharyngeal arch give rise to?
The stapedial artery
What does the tongue develop from?
From endodermal covered swellings on the floor of the pharynx.
What is Craniofacial Microsomia?
Caused by lack of neural crest cells, those that migrate to lateral and lowest parts of face have defects. They also usually have deformed external ear.
What is chromatin?
The combination of DNA, histone, and other proteins that make up chromosomes and is found inside the nuclear envelope of eukaryotic cells.
Dentinogenesis takes place throughout our entire lives. True or False?
True. Secondary dentin production happens.
What does sagittal synostosis result in?
Bitemporal narrowing and prominence in frontal and occipital.
What do all cleft lip and palate patients receive before undergoing surgical repair?
Pre-surgical orthopedic treatment.
What is the difference between growth sites and growth centers?
A growth site is merely a location at which growth occurs, a growth center is a location at which independent (genetically controlled) growth occurs.
What are some bodily physical abnormalities in down syndrome patients?
Small stature, dysplasia of pelvis, dysplasia of midphalanx of fifth finger, short metcarpals and phalanges, simian crease, cardiac anomalies (often needed to consult with cardiologist for antibiotic prophylasix, wide gap between first and second toe.
What are the two ways that help the maxilla grow downward and forward relative to the cranium and cranial base?
- A push from behind created by the cranial base growth 2. Growth at the sutures -Before the age of 7, it is largely the cranial base growth doing the work, and at 7, the cranial base growth stops and sutural growth is the only mechanism for bringing the maxilla forward. This is accomplished by growth of the soft tissue.
When can a neonatal mandibular distraction osteogenesis be used?
It can be used to treat Pierre Robin syndrome. It starts with an osteotomy on both sides of lower jaw, and a small metal device is placed under the skin, two days later, a callus forms, and the device is activated and slowly opens the osteotomy gap and moves the lower jaw forward and opens the baby’s airway, and weeks later, the device is removed.
What is the main cause of a teratoma?
When a primordial germ cell becomes stranded during migration to the dorsal body wall, they can rest at extragonadal sites and can give rise to a teratoma.
What are some factors that affect growth besides genetic factors?
Nutrition, health, illness, physical ativity, etc.
How does fusion of the secondary palate take place?
First ventrally and then proceeds dorsally along the midline.
What is minor clefting?
Involves only the soft tissue of the lip and results in a notch in the vermillion border of the lip just lateral to the philtrum called a partial cleft.
Why is Vitamin D essential and what can it’s deficiency lead to?
It is essential for the body to absorb calcium, for bone development, immune functioning, and alleviation of inflammation. It’s deficiency can lead to rickets, weakened immune system, osteomalacia, etc. Too much of it though can lead to increased risk of heart disease and kidney stones because of body absorbing too much calcium.
Amelogenesis takes place throughout our entire lives. True or False?
False. it only happens once, and ends once the ameloblasts are lost within eruption within the REE.
What are the two main drugs that can cause cleft lip?
- Phenytoin - anticonvulsant2. Vitamin A (Accutane)
What happens during Metaphase of Mitosis?
The centrosomes are at opposite poles of the cell, and the chromosomes are highly coiled condensed and arranged at the metaphase plate. Each sister chromatid is attached to a kinetochore microtubule coming from the closest pole.
With TNM staging, what is N2a, N2b, and N2c?
N2a is when it has spread to one lymph node on the same side as the primary tumor and it measures from 3-6 cm across.N2b is when it has spread to 2 or more lymph nodes on same side and none larger than 6 cm across.N2c is when it has spread to one or more lymph nodes on both sides of neck or opposite side of tumor, and none larger than 6 cm across.
What does the fourth pharyngeal pouch develop into?
Dorsal portion of fourth pharyngeal pouch develops into the superior parathyroid gland, while ventral portion develops into the ultimobranchial body, which is a sac or pouch
Is there more growth of the lower limbs or the upper limbs during postnatal life?
Lower limbs
What is a secondary tumor?
A tumor that formed from cells that have spread.
What are the main three synchondroses in the cranial base?
- Spheno-occipital synchondroses 2. Inter-sphenoid synchondroses 3. Spheno-ethmoid synchondroses
What is the primitive choana?
It is formed when the oronasal membrane ruptures during the seventh week to form an opening called the primitive choana.
What is the name of the area formerly known as the blastocyst cavity once Heuser’s membrane has formed?
It is now called the primary yolk sac.
What do the maxillary swellings do during the fifth week?
They enlarge and grow ventrally and medially simultaneously.
What does the cap stage consist of?
Dental lamina with a mesenchymal invasion below called the dental papilla.
With TNM staging, what is T0?
Carcinoma in situ, still localized and contained within top layers of cells lining oral cavity or oropharynx.
What are some symptoms of ankylosis of the TMJ or scar tissue development?
Limited openings and excursive movements, deviation of opening, cross-bites, short ramus height, hyper-eruption of the teeth on opposite side.
What is the process of compaction involving cleavage?
Compaction is when the blastomeres that are being cleaved, their outer surface become convex and their inner become concave, it changes their cytoskeleton. This segregates some of the blastomeres to the center of the morula and others to the outside.
B what day does the morula does it begin to absorb fluid? And which fluids?
By day 4. The trophoblast express a basally polarized Na/K pump, which pumps sodium into the interor of the morula, and water follows, and as the hydrostatic pressure increases, a large cavity called the blastocyst cavity (blastocoel) forms within the morula.
What are the two most common missing teeth?
Maxillary lateral incisors and mandibular 2nd premolars
What is the N number and ploidy at the start and end of Mitosis?
In mitosis, a diploid 2N cell replicates its DNA becoming a diploid 4N cell, and undergoes a single division to yield two diploid 2N daughter cells. For Big N, just count the number of chromosomes (or what I like to call chromatids). And the only haploid cells will be at the end of Meiosis I (secondary spermatocytes and secondary oocyts), and the end of Meiosis II (gametes).
What does PTH do to the kidney and what does it act on?
PTH stimulates the 1-alpha hydroxylase activity in the kidney, resulting in an increase in 1,25 dihydroxyvitamin D production. It also increases the reabsorption of calcium in the distal renal tubules. It also decreases the reabsorption of phosphorus in the proximal renal tubules.
What innervates the third pharyngeal arch?
The glossopharyngeal nerve IX
What is the name of the cells that detach as neurulation occurs? And what do they do?
Neural crest cells, and they undergo an epithelial to mesenchymal transformation and migrate to numerous locations in the body. The route they take and where they stop determines what they will be.
What is the process of remodeling?
The balance of apposition and resorption, with new bone being formed while old bone being removed. It is seen at the surfaces of bones that are growing by endochondral replacement as well as bones that are formed directly within a connective tissue membrane.
What are the epithelial cell rests of Malassez?
When HERS disintegrates with the formation of the PDL, these are their remnants, and can cause future periodontal problems if cystic.
What becomes the permanent teeth?
The dental lamina superficial to each primary tooth bud produces a small diverticulum, that migrates and becomes the bud of the permanent tooth.
Between what two cavities does the bilaminar disc lay?
Between the amniotic cavity and the blastocyst cavity (blastocoel)
What causes a facial cleft?
Complete or partial failure of fusion between any of the five facial swellings. Can be unilateral or bilateral.
What did the Journal of Orthodontics study in 1998 say about third molar removal affecting mandibular incisor crowding?
Their removal does not reduce or prevent late incisor crowding.
What needs to take place for ameloblasts to form?
As soon as mineralized dentin is formed, cells of the IEE differentiate into the ameloblasts, and begin to secrete enamel prisms.
What is aneuploidy?
When a cell contains an incorrect number of chromosomes. Usually happens because of failure to line up at metaphase plate.
What happens during Telophase of Mitosis?
The chromosomes assemble in sets at the two poles, they begin to uncoil. A nuclear envelope reforms around each chromosome set, the spindle disappears, and the nucleolus reforms. Nuclear division by mitosis is complete at this point.
What is the name of the midline swelling that the second pharyngeal arch develops in developing the tongue?
Copula
What changes with growth with mineralized tissues?
Hyperplasia, hypertrophy, and secretion of extracellular material can only occur on the surface, not within the mineralized mass. Direct addition of new bone occurs through the activity of cells in the periosteum, and is called direct or surface apposition of bone.
What is though to be the most common cause of congenital mental retardation in the western world?
Alcohol
What is the end result of Meiosis?
Produces four mature gametes (meiocytes) containing 23 chromosomes (one of each pair) in each cell and are said to be haploid 1N.
Does more bone deposition occur on the sphenoid or occipital part of the spheno-occipital synchondrosis?
Occipital
What is the Bolton discrepancy?
It is when the tooth size ratio of the maxillary and mandibular teeth will not accommodate a proper occlusal relationship. Common with Kinefelter syndrome.
What are the characteristics associated with myelomeningoceles?
Most serious type of Spina Bifida, with this, a sack of fluid comes through the opening in the baby’s back, and in this sack is part of the spinal cord and nerves.
Which cells secrete calcitonin? And when?
Thyroid gland parafollicular cells, also called C cells. Extra calcium in blood elicits the C cells to release Calcitonin, and calcitonin reduces blood calcium by inhibiting the activity of osteoclasts, and by decreasing the re-absorption of calcium in the kidneys, which leads to lower blood calcium levels.
What needs to happen for amelogenesis and dentinogenesis to occur?
A message is sent from the newly differentiated odontoblasts to the IEE, causing the epithelial cells to turn into active secretory ameloblasts, and dentinogenesis is in turn dependent on signals from the differentiating IEE in order for the dentinogenesis process to continue.
What innervates the maxillary and mandibular processes of the first arch?
The maxillary and mandibular branches of the trigeminal nerve V
What is intramembranous ossification?
It is the embryonic development of flat bones from the embryonic tissue called the mesenchyme.
At what plaque pH can remineralization start to occur?
Above 5.5. Above this pH, interbacterial plaque fluid and saliva return to being saturated and then supersaturated, with respect to hydroxyapatite.
What is the bilaminar disc made up of?
An epiblast (primary ectoderm) and a hypoblast (primary endoderm)
Why don’t ploidy and N number always coincide?
Because each chromosome contains one or two molecules of DNA at different stages of the cell cycle (whether mitotic or meiotic)
Around day 11-13, what is the name of the region that begins to anastamose with maternal capillaries and become filled with blood?
The cytrotrophoblastic lacunae
With TNM staging, what is N1?
The cancer has spread to one lymph node on the same side of the head or neck as the primary tumor, and the lymph node is smaller than 3 cm across.
What nerve innervates all of the small salivary glands in the insides of the cheeks, lips, and hard palate, above the level of the oral fissure?
Greater petrosal branch of the Facial nerve - CN VII
What is the name of the daughter cells that they zygote is divided up into during cleavage? And what is the name of the 32-cell stage?
Blastomeres. Morula.
What is the articular cartilage on the mandible?
It is found on the condyle and is part of the condylar cartilage that isn’t converted to bone.
What is the nasolacrimal duct?
When ectoderm at the floor of the nasolacrimal groove groove invaginates into the underlying mesenchyme, it forms a tube called the nasolacrimal duct.
What gives rise to the primary palate?
The floor of the nasal cavity is formed by a posterior extension of the intermaxillary process called the primary palate.
From where does the maxilla initially form?
From a center of mesenchymal condensation in the maxillary process
What are the aortic arches?
They are a series of six paired embryological vascular structures which give rise to several major arteries.
What has cleft lip been attributed to?
Underdevelopment of the mesenchyme of the maxillary swelling, which results in inadequate contact of the maxillary swelling with the intermaxillary process.
What is the name of the process of cell migration, invagination, and ingress that occurs around the beginning of week 3?
Gastrulation
What is the most common feature of Turner syndrome?
Short stature, and you can usually tell by age 5. Most Turners have normal intelligence.
At what pH can damage start happening to fluoroapatite structures?
4.5
What is holoprosencephaly?
HPE is a birth defect of the brain, which effects the development of midline facial features, including closely space eyes, microcephaly, cleft lip, cleft palate. It is caused by failure of the prosencephalon (forebrain) to divide into the doubles lobes of the cerebral hemisphere. It ranges from mild to severe. Sever cases only have one nostril, one joined eye, triangular skull. Mutations in the gene encoding the sonic hedgehog protein, which is involved in the development of the CNS, can cause holoprosencephaly. Also, toxins such as alcohol can cause it.
At what age does the condylar growth rate peak? And at what age is it complete?
12 to 14 years old, usually by age 20.
By what type of ossification do the maxilla, zyogmatic, and temporal bones form?
Intramembranous ossification
What is cleidocranial dysplasia?
It is a skeletal dysplasia with delayed closure of the cranial sutures, hypoplastic clavicles, and multiple dental problems. Supernumerary teeth, short stature, extra set of adult teeth, wide-open fontanelles, narrow sloping shoulders, brachydactyly, wide-open metopic suture in front.
What is the neural plate?
It appears as a thickening of the ectoderm on either side of the midline, cranial to the primitive node.
What is the name of the membrane that the hypoblast produces that helps form the definitive yolk sac?
It is called the endodermal lining of the definitive yolk sac. And remember that the hypoblast also helps form the extraembryonic endoderm, that turns into Heuser’s membrane, which then surrounds the newly formed primary yolk sac.
What three main things is bone made up of?
- Collagen2. Calcium-phosphate mineral complexes 3. Bone cells (osteoclasts, osteoblasts, osteocytes)
Which way do the enamel rods face?
Their heads face the cusp tip and the tails face the cervical margin. Each rod is about 1 to 3 mm in length.
What happens during Meiosis I - Anaphase I and Telophase I?
In anaphase I, homologous chromosomes separate by moving to separate poles. The cell then proceeds through telophase I, with one double-stranded chromosome of each homologous pair distributed to each daughter cell, the cell then undergoes cytokinesis and the cell divides. Each of the two daughter cells is now Haploid 2N, with half the number of chromosomes per nucleus.
What nerve supplies the motor component of the tongue? What is the exception?
CN XII-Hypoglossal nerve, except for the palatoglossus muscle, which is supplied by the pharyngeal branch of the CN X-Vagus nerve.
What are the two kinds of chromatin?
Euchromatin and Heterochromatin
Where does the center of ossification of the maxilla appear?
It appears in the angle between the anterosuperior alveolar nerve and the inferior orbital nerve.
With TNM staging, what is T4a and T4b?
T4a is when the tumor is growing into nearby structures, at this stage it is called a moderately advance local disease.T4b is when the tumor has grown through nearby structures and into deeper areas. At this stage it is called a very advanced local disease.
On what day of human development is the notochordal process complete?
Day 20
What do polar microtubules do?
They meet in the middle and overlap for a second and attach to each other. The polar and aster stabilize mitosis the most.
What packages chromosomes into the condensed structure called chromatin?
Histone proteins
What is the name of the layer that the hypoblast is replaced by when the ingressing epiblast cells invade and displace their cells?
The definitive endoderm
What is an NTD?
Neural tube defect
What is growth of the cranial base primarily the result of?
The endochondral growth and bony replacement at the synchondroses, which have independent growth potential but are perhaps also influenced by growth of the brain.
What nerve supplies sensory to the parotid gland?
The auriculotemporal nerve of the mandibular branch of the trigemincal nerve - CN V.
What type of sperm are constantly undergoing mitosis in the testes so that the number of them doesn’t decrease
Spermatogonia. They progress through the seminiferous epithelium supported by Sertoli cells and undergo the two meiotic divisions which give rise to four future-spermatazoa, with each containing half the normal human genetic content, which can then combine with an oocyte to form a diploid zygote.
In what direction does the notochordal plate form from the hollow notochordal process fusing with the underlying endoderm?
In a caudal to cranial direction
What does the parotid gland develop from?
A groove-like invagination of ectoderm that forms in the crease between the maxillary and mandibular swellings during week six, the groove turns into a tubular duct which sinks into the underlying mesenchyme toward the ear, then later on is transferred to the inner surface of the cheek, and the opposite end of the tube becomes the parotid gland, and the tube becomes the parotid duct. The submandibular and sublingual glands develop similarly, from invaginations of the endoderm in the floor of the oral cavity and in the paralingual sulci on either side of the tongue, respectively.
What is heterochromatin?
It is the condensed chromatin that is folded, tightly coiled like a telephone cord, which allows the cell’s DNA to be packed into the nucleus
What do cranial base synchondroses serve as and which one has particular importance because of its late ossification and important contribution to post-natal cranial base growth?
They serve as growth centers of the craniofacial skeleton, and the spheno-occipital synchondrosis is very important. The inter-sphenoid and spheno-ethmoid synchondroses are typically stable and show very little growth after 7 years of age.
What is the caudal eminence?
As gastrulation proceeds the primitive streak regresses cranially to caudally and by day 26, so during week 4, it leaves a caudal midline mass of mesoderm behind called the caudal eminence.
What are the three secondary cartilages that develop between the 10th and 14th week?
- Condylar cartilage 2. Coronoid cartilage 3. Symphyseal cartilage
Not all skeletal cartilage acts the same when transplanted. True or False?
True. If a piece of epiphyseal plate (a growth center) of a long bone is transplanted, it will continue to grow in a new location or in culture. The same applies for transplanting the nasal septum (a growth center). However, little or no growth of the mandibular condylar cartilage (a growth site) was seen after transplantation.
What does the mesenchyme that covers the dorsal side of the neural tube end up giving rise to?
The vertebral arches and skull.
What are the four growth areas of the craniofacial complex?
- Cranial vault (the bones that cover the upper and outer surface of the brain) 2. Cranial base (the bony floor under the brain, which also is the dividing line between the cranium and the face) 3. Nasomaxillary complex (Nose, maxilla, and associated small bones) 4. Mandible
From what three pairs of cartilaginous precursors does the chondocranium develop from?
- Ethmoid prechordal cartilage2. Sphenoid hypophyseal cartilage3. Occipital parachordal cartilage
What ploidy are mature gametes like spermatozoa and a definitive oocyte?
They are haploid
How many pairs of autosomes vs sex chromosomes in each nucleus?
22 pairs of autosomes and 1 pair of sex chromosomes (XX or XY)
What happens to most of the anterior surface of the maxilla has it grows downward and forward?
It is remodeled and bone is removed.
What will be the blood calcium, phosphorus and renal calcium and phosphorus levels in Hyperparathyroidism (high PTH)?
High calcium, low phosphorus, and high urinary calcium and phosphorus.
What is the process of cleavage?
Subdividing the zygote without increasing its size.
What forms the intermaxillary process?
By the end of week 7, the inferior tips of the medial nasal processes expand laterally and inferiorly and fuse to form the intermaxillary process.
What does the hypoblast form when it sends out a proliferation of cells that lines the cytotrophoblast by day 9? And the part that lines the former blastocyst cavity, what is the name of this membrane?
It forms the extraembryonic endoderm. Heuser’s membrane. And at the same time of all this, the extraembryonic mesoderm forms
What becomes the tooth pulp?
The inner mesenchyme of the dental papilla.
What is Apert’s syndrome?
Caused by nucleotide alterations resulting in amin-acid substitutions, leading to mutation in FDFR2 gene located on chromosome 10. Craniosynostosis and symmetric syndactyly of the extremities are hallmarks. Wide-set eyes, mid-face hypoplasia, class III occlusion.
What is Crouzon’s syndrome?
Premature fusion of certain skull bones (craniosynostosis), and this leads to wide-set bulging eyes from underdevelopment of midface, vision problems, eyes that do not point in same direction (strabismus), beaked nose, underdeveloped jaw. This is the most frequent occurring member of Craniosynostosis syndromes. It arises because of prenatal fusion of superior and posterior sutures of the maxilla along wall of orbit, which produces distortions. Also caused by mutation in FGFR2 gene, which provides instruction for making a protein called fibroblast growth factor receptor 2.
What innervates the sixth pharyngeal arch?
The recurrent laryngeal branch of vagus nerve X
Does the embryo grow faster in length or in width?
In length, cranially and caudally.
Around the TMJ, two clefts appear in the mesenchyme producing the upper and lower joint cavities, but what does the mesenchyme surrounding the developing joint become?
The intra articular disk
What is the nasolacrimal groove or furrow?
It is a groove between the lateral nasal process and the adjacent maxillary swelling.
During what stage does amelogenesis occur?
During the bell stage
What has now blanketed the entire (except for a small region at the abembryonic pole) implanted blastocyst by day 9?
The syncytiotrophoblast
At what age do most kids born with cleft lip or palate have surgery to repair them?
Within the first 12-18 months of life
What does the third arch cartilage, which originates from neural crest cells, give rise to?
The lower rim of the hyoid bone and the greater horn of the hyoid
What does Diploid or 2n mean?
When a cells chromosomal number consists of two sets of chromosomes (one from mother and one from father), it is referred to as Diploid and can be denoted as 2n
How many chromosomes are formed during Telophase II?
Four haploid nuclei (containing chromosomes with single chromatids) are formed in Telophase II. And these four cells are not identical because of the genetic diversity that took place in Meiosis I.
How does the remodeling of the palatal vault differ from the remodeling of the maxilla?
The palatal vault is carried downward and forward along with the rest of the maxilla but at the same time, bone is removed on the nasal side and added on the oral side, thus creating an additional downward and forward movement of the palate.
What does the third pharyngeal pouch develop into?
Dorsal portion of third pharyngeal pouch develops into the inferior parathyroid gland, while ventral portion develops into the thymus
What are the characteristics associated with meningoceles?
With this type, a sack of fluid comes through an opening in the baby’s back, but the spinal cord is not in this sac, and usually little or no nerve damage.
What is the name for the two identical chromosomes resulting from DNA replication?
Sister chromatids
What generates bioelectric charges in bone as it pertains to theories of growth?
Distortions of the collagen crystals in bone cause a minute deformation of the bone matrix due to mechanic strain, generating bioelectric signals or charges in the immediate area of deformation. These altered electric potentials appear to relate either directly or indirectly to the triggering of osteoblastic and osteoclastic responses.
What innervates the fourth pharyngeal arch?
The superior laryngeal branch of vagus nerve X
What do the neural crest cells that migrate to lower regions of the facial area help form?
Aorta, pulmonary artery, aortic arch, etc. This is why many syndromic patients have heart defects.
During what week of embryonic development does the embryoblast split into two layers forming a bilaminar disc?
Second week
What are the three layers of the enamel organ?
- IEE2. Middle enamel reticulum3. OEE
What is the name of the structure that the thyroid gland originates from?
It is the foramen cecum, and it is found on the developing tongue
Does more bone deposition occur on the ethmoid or sphenoid part of the spheno-ethmoidal synchondrosis?
Ethmoid
In which direction does closure of the neural groove (fusion of the neural folds) take place?
It begins at the occipitocervical region and proceeds both cranially and caudally.
What does the ultimobrachial body do?
The ultrimobranchial body releases signaling factors to induce migration and differentiation of nearby neural crest cells into the parafollicular cells of the thyroid gland.
What structure appears at the beginning of the third week? And what three structures does it contain?
The primitive streak (faint midline structure), which contains the primitive groove, the primitive pit, and the primitive node.
What innervates the taste component of the anterior 2/3 of the tongue?
It is supplied by the chorda tympani branch of CN VII-facial nerve, which innervates all taste buds except the circumvallate papillae.
At what stage is the embryo called blastocyst?
When the morula has absorbed fluid and formed a blastocoel along with the inner cell mass.
By the end of what week do all five facial swellings appear by?
End of the fourth week
What is the most important trimester for normal embryological development?
First, 12 weeks.
What resembles Mitosis more, Meiosis I or Meiosis II?
Meiosis II
What did the Gilhuus-Moe and Lund study demonstrate regarding a mandibular condyle fracture?
That in a child, there was an 80% chance that the condylar process would regenerate to approximately its original size. The condyle regenerates directly from periosteum at the fracture site, because all of the original bone and cartilage resorb.
The maxilla grows more and later than the mandible. True or False?
False. Just think that the maxilla is closer to the brain, which also grows slower.
What percentage of conceptions result in spontaneous abortion because of chromosomal abnormalities?
40-50%
Where are motor proteins found and how do they move along?
They are found on the spindle microtubules and utilize ATP hydrolysis to move along. They are required for spindle formation, chromosome alignment, and segregation, and are required for the cell to avoid aneuploidy, a hallmark of cancer.
What is the concept of pattern?
The change of proportional relationships over time
What are the two most common types of facial clefts?
Cleft lip and cleft palate
When the intraembryonic mesoderm cells migrate LATERALLY, what do they organize into and form, and what does this end up giving rise to?
They form the somitomeres (somites), which give rise to vertebral columns, skeletal musculature, and dermis.
What is found at the outer end of each epiphyseal plate?
A zone of actively dividing cartilage cells. As long as the rate at which cartilage cells proliferate is equal to or greater than the rate at which they mature, growth will continue.
What is the name of the layer that is formed when some of the epiblast cells migrate through the primitive streak into the space between the epiblast and definitive endoderm?
The intraembryonic mesoderm
What is the difference between the primitive and definitive choana?
Once the nasal septum forms, the nasal passages open into the pharynx behind the secondary palate through the primitive choana, but is now called the definitive choana.
What causes Down Syndrome?
Embryos formed by fusion of a gamete with two copies of chromosome 21 and with a normal gamete results in trisomy 21. 95% of all Down Syndrome cases are caused this way.
Is a suture a growth site or growth center?
Growth site
How does growth of the mandible differ from growth of the maxilla?
In contrast to the maxilla, both endochondral and periosteal activity are important in growth of the mandible, and displacement created by growth of the cranial base plays a negligible role.
Normally, is most of the calcium that enters glomerular filtrate reabsorbed back into the blood, or excreted?
Reabsorbed back into blood to preserve blood calcium.
What causes anencephaly?
It happens if the upper part of the neural tube does not close all the way, and babies are born without front part of brain, cerebrum, or remaining parts are not covered by bone or skin.
What forms the cementoblasts?
The inner cels of the dental sac/follicle differentiate into the cementoblasts.
What is a teratogen?
Chemical and other agents capable of producing embryologic defects if given at a critical time. At high levels, can cause death.
When do the ameloblasts lose their ruffled borders?
As enamel maturation nears completion.
During what phase of the cell cycle does DNA replication take place, and how long does it take?
Occurs during S phase (S for synthesis) and takes about 10-12 hours, and makes up half of the cell-cycle time in a cell. Whereas the M phase for chromosome segregation and cell division only takes an hour.
During what month is there an in-growth of blood vascular elements into various points of the chondocranium?
Fourth month. These areas become centers of ossification, at which cartilage is transformed into bone (endochondral ossification) and islands of bone appear in the sea of surrounding cartilage.
What four things is Tetralogy of Fallot composed of?
- Pulmonary stenosis2. Right ventricular hypertrophy3. Overriding aorta (is huge and arises from both left and right instead of just left ventricle.4. Ventricular septal defect (VSD)
What type is 3-4% of all cases of Trisomy 21 due to?
Robertsonian Translocation. Which is when two breaks occur in separate chromosomes, usually 14th and 21st. So there is triplication of the 21st chromosome material. Partial trisomy 21 is when these people have only triplication of part of the 21st instead of the whole chromosome, and this is inherited.
What is translocation?
When a copy of chromosome 21 in a developing gamete becomes attached to the end of another chromosome, suchas chromosome 14, during the first or second division of meiosis. This can also cause Down Syndrome.
When do most gene mutations occur?
After you’re born, and they are not inherited. Smoking, radiation, viruses, carcinogens, obesity, hormones, and a lack of exercise can all cause gene mutations. And these gene mutations combine and can make us more likely than others to develop a specific type of cancer.
What is the NAM device?
It is a NasoAlveolar Molding device, and can be elaborate or passive. it consists of an intraoral acrylic plate held in place with extraoral elastics and tape. And in later phases, wire outriggers are added that apply protracting forces to the vestibule of the nares.
What is the lateral cervical sinus?
It is when the second pharyngeal arch overgrows clefts 2, 3, and 4 and fuses caudally with the cardiac eminence to form this transient ectoderm-lined structure, which normally just disappears. However, it occasionally persists on one or both sides in the form of a cervical cyst, just anterior to sternocleidomastoid muscle.
What is the name glycoprotein layer that surround a zygote?
The zona pellucida, and it surrounds the zygotes plasma membrane. It plays a role in zygote development, protection, fertilization, and preventing premature implantation.
What are the main errors that cause cleft palate?
Inadequate growth of the palatine shelves, failure of shelves to elevate at correct time, excessively wide head, failure of shelves to fuse, secondary rupture after fusion.
With Pierre Robin syndrome, does the relationship between the upper and lower teeth improve or get worse as the child grows?
It improves.
Where does the actual growth of the mandible occur?
The chin is translated downward and forward as the actual growth occurs at the mandibular condyle and along the posterior surface of the ramus.
