Developmental abnormalities genetic and environment Flashcards
What are the mechanisms of abnormal development?
- 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
What is a neural tube defect?
- 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
What is spina bifida?
- Neural tube defect
- Results in spinal cord malformation and failure of formation of the overlying dorsal portion of the vertebra
What is spina bifida occulta?
- Same as spina bifida but there is a bony change in one or more vertebra
- doesn’t affect nerves within the spinal column
Morphologic diagnosis for this image?
Hard palate, cleft
“Cleft palate”
“Palatoschisis”
What is ectopic cordis?
- Growth of the heart in an aberrant location
What is “ectopic”
- Growth of a tissue outside of where is normal
- Used in morphologic diagnosis
- Ex:
- Duodenum, ectopic pancreas
- abnormal pancreas tissue found on the duodenum
- Duodenum, ectopic pancreas
- Ex:
What is “Diphagus”?
two jaws
What is “Polydactyly”?
Additional digits
How are conjoined twins morphologically described?
- “-pagus” - fixed or united
- Ex:
- Cephalothoracopagus
- fusion of head and thorax of conjoined twins
- Cephalothoracopagus
What is “-parapagus”?
- Conjoined twins that lie side-by-side with ventrolateral fusion
- Ex:
- Dicephalic parapagus
What is “holoprosencephaly?
- Failure of proper differentiation of the embryonic forebrain (prosencephalon)
- Features vary widely from microencephaly, hydrocephalus, facial anomalies and clefts, cyclopia, single upper incisor
What is “Schistosomus reflexus”?
- 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
What is “Amorphous globosus”?
- A spherical fetus that lacks differentiation of phenotypic body parts
- Inner part consists of various degrees of differentiation of mesodermal and ectodermal tissues
What are examples of musculoskeletal developmental diseases?
- Amelia
- Hemimelia
- Arthrogryposis
- Chondrodysplasia
- Osteopetrosis
What is “amelia”?
Absence (or near absence) of a limb or limbs
What is “hemimelia”?
The absence of all or part of the distal part of a limb
What is “Hemivertebrae”?
- Half of the vertebral body fails to form, often resulting in a wedge-shaped vertebra
- Common cause of scoliosis
What is “scoliosis?”
What is “kyphosis”?
- Scoliosis: lateral deviation of the spine (sideways curvature)
- Kyphosis: Dorsal/ventral deviation of the spine
What is “arthrogryposis”?
flexure or contracture of a joint
What is “brachygnathia”?
Shortening of the mandible relative to the maxilla
“Overbite”
What is “prognathia”
Lengthening of the mandible relative to the maxilla
“Underbite”
What is “Chondrodysplasia”?
- abnormal development of cartilage
- Results in short long bones and spine (Dwarfism)
- Normal phenotypic trait in certain dog breeds (Dachshunds, English bulldog, etc)
What is Osteopetrosis?
- 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
What are examples of Nervous system developmental diseases?
- Anencephaly
- Microencephaly
- Hydrocephalus
- Hydranencephaly
What is anencephaly?
- Neural tube defect
- All or part of the brain and skull are absent
What is microcephaly?
- Head is smaller than normal
- Often a smaller incompletely developed brain
What is Hydrocephalus?
Excessive fluid in the ventricles of the brain
What is hydranencephaly?
- Failure of formation of parts of the cerebrum
- usually white matter
What is porencephaly?
Cyst or cavity within the cerebrum due to abnormal development or destructive/viral lesions
What is Aortic and pulmonary stenosis?
- Narrowing of the aortic or pulmonary valves
- Restricts blood flow
- Ventricular hypertrophy will be a secondary event
What is patent ductus arteriosus?
- 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
What is Truncus arteriosus?
- Failure of separation of the aorta and pulmonary artery
- Results in a single common vessel with a single common valve (truncal valve)
What is tetralogy of Fallot?
- 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
What are ventricular septal defects?
- Incomplete formation of the interventricular septum
- Results in holes that allow communication between the right and left ventricles
What is a hermaphrodite?
- Individual with both ovarian and testicular tissue
- Sometimes combined as an ovotestis
- And ambiguous external genitalia
- Chromosomes have both male and female components (mosaicism)
What is a pseudohermaphrodite?
- 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
What is freemartinism?
- 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)
What is Epitheliogenesis imperfecta?
- 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
What is Hypotrichosis?
Reduction in the amount of hair
What is collagen dysplasia?
- Group of diseases of connective tissue that result in reduced strength of affected tructures
- Cutaneous astheni
- Ehlers-Danlos-like Syndromes
- Osteogenesis imperfecta
What is Ichthysis?
- Conditions characterized by thick, dry, scaling skin
- sometimes resemble fish scales
