NP3A Flashcards
Defects present at birth is known as
congenital defect
defects can be acquired, caused by agents that destroy rapidly dividing cells
radiomimetic agents
What will give rise to the CNS?
Ectoderm
_________ development continues into the post-natal period
cerebellar
_________ follows the establishment of neuronal networks, and so this too occurs in late gestation and continues into the post-natal period
myelination
insults early in gestation will reflect defects in ___________ closure
neural tube
What determines outcome?
magnitude and timing of the insult
Embryo survives and lesions will impact either the:
- rostral neural tube
- caudal spinal cord and bony encasement
forebrain and bony encasement is example of:
rostral neural tube
early and severe insult can result in lack of the tissue to form
aplasia
early insult that is not as severe can cause
segmental aplasia
insults that occur later may allow to form that simply looks smaller
hypoplasia
all of the developmental defects will be accompanies by some degree of tissue disorganization at the microscopic level
dysplasia
defects in neural tube close are referred to as a
dysraphism
(spinal or cranial dysraphism)
malformation of the spinal cord, development defect may be appreciated grossly or only microscopically and the change is described as a
myelodysplasia
a congenital defect of the spine in which part of the spinal cord and its meninges are exposed through a gap in the backbone. It often causes paralysis of the lower limbs, and sometimes mental handicap
spina bifida
is an umbrella term that describes a number of conditions present at birth that affect the spine, spinal cord, or nerve roots
Spinal dysraphism
(spinal cord is out of the body) If we survive that, bacteria are certain to invade the central nervous system since we have a path from the outside world into the spinal cord – a _________________ will follow
suppurative meningomyelitis
can cause aplasia, segmental aplasia, or hypoplasia of forebrain components
and we encounter a problem similar to what we encountered with dysraphism of the spinal cord – secondary failure to induce the surrounding mesoderm to form bone.
Cranial Dysraphism
A developmental birth defect in which the cranium fails to close completely, so that the brain is exposed to the amnios and eventually degenerates, causing anencephaly
cranioschisis
is normally an enteric pathogen, but when entering a developing embryo/fetus, will destroy rapidly dividing cells. This property of killing rapidly dividing cells is what we see with radiation exposure
Bovine Viral Diarrhea virus (BVDv)
is a serious birth defect in which a baby is born without parts of the brain and skull
Anencephaly
the caudal (posterior) part of the forebrain, containing the epithalamus, thalamus, hypothalamus, ventral thalamus, and the third ventricle.
diencephalon
another word for midbrain
mesencephalon
Using the BVDv example, and knowing that mean gestation in cattle is approximately
280 days. Exposure at a gestation age of less than 100 days results in:
Fetal Death
Using the BVDv example, and knowing that mean gestation in cattle is approximately
280 days. Infections between 100-170 days of gestation cause:
- Cerebral aplasia or hypoplasia, representing infection early in this range
- porencephaly
- cerebellar aplasia or hypoplasia, representing infection early in this range
Using the BVDv example, and knowing that mean gestation in cattle is approximately
280 days. Infections between 100-170 days of gestation cause Porencephaly which is:
a defect in a cerebrum that has largely formed, and this would reflect infection during the middle of this range
Using the BVDv example, and knowing that mean gestation in cattle is approximately
280 days. The fetus is immune to effects of the virus after _______ days
170
This Persian cat (neonate) has a large portion of calvarium that has failed to form, with exposure to brain and meninges. Here, the defects in the forebrain are not grossly apparent, but there was a clear lack of communication between the developing forebrain and the surrounding mesenchymal tissues. This lesion could be caused by:
exposure to a radiomimetic agent (e.g., virus or toxin) or it can be heritable. Breeding history revealed this to be a heritable (autosomal recessive) defect, with variable expression of this lesion in different litters from the same dam.
What is the primary functional significance of spina bifida?
Spina bifida predisposes the animal to dynamic spinal cord compression