Developmental abnormalities genetic and environment

Question 1

What are the mechanisms of abnormal development?

Answer 1

• Arrest or inhibition of development
• Persistence of fetal structures
• Failure of closure of fetal grooves and fissures
• Growth in aberrant locations
• Duplications
• Lack of coordination of growth and differentiation

Question 2

What is a neural tube defect?

Answer 2

• Defect in closure of the neural tube
• Resulting conditions can include anencephaly, encephalocele, and spina bifida (myelomeningocele) resulting in failure of formation of the overlying dorsal portion of the vertebra
• Types include myelomeningocele, meningocele, and spina bifida

Question 3

What is spina bifida?

Answer 3

• Neural tube defect
• Results in spinal cord malformation and failure of formation of the overlying dorsal portion of the vertebra

Question 4

What is spina bifida occulta?

Answer 4

• Same as spina bifida but there is a bony change in one or more vertebra
  
  • doesn’t affect nerves within the spinal column

Question 5

Morphologic diagnosis for this image?

Answer 5

Hard palate, cleft

“Cleft palate”

“Palatoschisis”

Question 6

What is ectopic cordis?

Answer 6

• Growth of the heart in an aberrant location

Question 7

What is “ectopic”

Answer 7

• Growth of a tissue outside of where is normal
• Used in morphologic diagnosis
  
  • Ex:
    
    • Duodenum, ectopic pancreas
      
      • abnormal pancreas tissue found on the duodenum

Question 8

What is “Diphagus”?

Answer 8

two jaws

Question 9

What is “Polydactyly”?

Answer 9

Additional digits

Question 10

How are conjoined twins morphologically described?

Answer 10

• “-pagus” - fixed or united
• Ex:
  
  • Cephalothoracopagus
    
    • fusion of head and thorax of conjoined twins

Question 11

What is “-parapagus”?

Answer 11

• Conjoined twins that lie side-by-side with ventrolateral fusion
• Ex:
  
  • Dicephalic parapagus

Question 12

What is “holoprosencephaly?

Answer 12

• Failure of proper differentiation of the embryonic forebrain (prosencephalon)
• Features vary widely from microencephaly, hydrocephalus, facial anomalies and clefts, cyclopia, single upper incisor

Question 13

What is “Schistosomus reflexus”?

Answer 13

• Syndrome with multiple malformations including:
  
  • Spinal inversion
  • Ventral midline abdominal cleft with externalization of abdominal viscera
  • Arthrogryposis/ankylosis
  • hypoplasia of the diaphragm and lungs
• Variable features include:
  
  • Cleft sternum and exposure of thoracic viscera
  • Scoliosis
  • Digestive defects
  • Urogenital defects

Question 14

What is “Amorphous globosus”?

Answer 14

• A spherical fetus that lacks differentiation of phenotypic body parts
• Inner part consists of various degrees of differentiation of mesodermal and ectodermal tissues

Question 15

What are examples of musculoskeletal developmental diseases?

Answer 15

• Amelia
• Hemimelia
• Arthrogryposis
• Chondrodysplasia
• Osteopetrosis

Question 16

What is “amelia”?

Answer 16

Absence (or near absence) of a limb or limbs

Question 17

What is “hemimelia”?

Answer 17

The absence of all or part of the distal part of a limb

Question 18

What is “Hemivertebrae”?

Answer 18

• Half of the vertebral body fails to form, often resulting in a wedge-shaped vertebra
• Common cause of scoliosis

Question 19

What is “scoliosis?”

What is “kyphosis”?

Answer 19

• Scoliosis: lateral deviation of the spine (sideways curvature)
• Kyphosis: Dorsal/ventral deviation of the spine

Question 20

What is “arthrogryposis”?

Answer 20

flexure or contracture of a joint

Question 21

What is “brachygnathia”?

Answer 21

Shortening of the mandible relative to the maxilla

“Overbite”

Question 22

What is “prognathia”

Answer 22

Lengthening of the mandible relative to the maxilla

“Underbite”

Question 23

What is “Chondrodysplasia”?

Answer 23

• abnormal development of cartilage
• Results in short long bones and spine (Dwarfism)
• Normal phenotypic trait in certain dog breeds (Dachshunds, English bulldog, etc)

Question 24

What is Osteopetrosis?

Answer 24

• Disorder characterized by increased bone density and abnormal bone remodeling
  
  • due to decreased bone resorption caused by osteoclast dysfunction
• Bone is fragile and predisposed to fractures
• Excess bone can compress normal tissues

Question 25

What are examples of Nervous system developmental diseases?

Answer 25

* Anencephaly * Microencephaly * Hydrocephalus * Hydranencephaly

Question 26

What is anencephaly?

Answer 26

* Neural tube defect * All or part of the brain and skull are absent

Question 27

What is microcephaly?

Answer 27

* Head is smaller than normal * Often a smaller incompletely developed brain

Question 28

What is Hydrocephalus?

Answer 28

Excessive fluid in the ventricles of the brain

Question 29

What is hydranencephaly?

Answer 29

* Failure of formation of parts of the cerebrum * usually white matter

Question 30

What is porencephaly?

Answer 30

Cyst or cavity within the cerebrum due to abnormal development or destructive/viral lesions

Question 31

What is Aortic and pulmonary stenosis?

Answer 31

* Narrowing of the aortic or pulmonary valves * Restricts blood flow * Ventricular hypertrophy will be a secondary event

Question 32

What is patent ductus arteriosus?

Answer 32

* Ductus arteriosus connecting the aorta and pulmonary artery doesn't close after birth * Allows oxygenated blood in the aorta to flow back to the pulmonary artery/lungs * Creates excessive blood flow to the lungs

Question 33

What is Truncus arteriosus?

Answer 33

* Failure of separation of the aorta and pulmonary artery * Results in a single common vessel with a single common valve (truncal valve)

Question 34

What is tetralogy of Fallot?

Answer 34

* Combination of pulmonic stenosis, ventricular septal defect, overriding aorta and right ventricular hypertrophy * Overriding aorta: * aorta is shifted slightly to the right and lies directly above the ventricular septal defect, receiving blood from both the right and left ventricles

Question 35

What are ventricular septal defects?

Answer 35

* Incomplete formation of the interventricular septum * Results in holes that allow communication between the right and left ventricles

Question 36

What is a hermaphrodite?

Answer 36

* Individual with both ovarian and testicular tissue * Sometimes combined as an ovotestis * And ambiguous external genitalia * Chromosomes have both male and female components (mosaicism)

Question 37

What is a pseudohermaphrodite?

Answer 37

* Individuals with mismatched reproductive organs and external genitalia * **Male pseudohermaphrodites: Testes** with chromosomal constitution of male but with ambiguous or **female external genitalia** * **Female pseudohermaphrodite: Ovaries** with chromosomal constitution of female, but **male external genetalia**

Question 38

What is freemartinism?

Answer 38

* twinning a heifer and a bull calf, in which there has been a sharing of common blood supply * placentas each merged together * Male hormones inhibit female repro tract development (hypoplasia for all components)

Question 39

What is Epitheliogenesis imperfecta?

Answer 39

* Absence of epithelium in discrete area of the skin nd mucosa * Most often present over the distal extremities * Defects can also occur in the oral cavity and tongue

Question 40

What is Hypotrichosis?

Answer 40

Reduction in the amount of hair

Question 41

What is collagen dysplasia?

Answer 41

* Group of diseases of connective tissue that result in reduced strength of affected tructures * Cutaneous astheni * Ehlers-Danlos-like Syndromes * Osteogenesis imperfecta

Question 42

What is Ichthysis?

Answer 42

* Conditions characterized by thick, dry, scaling skin * sometimes resemble fish scales