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histo final exam extravaganza! > Embryology > Flashcards

Embryology Flashcards

1
Q

Environmental causes of congenital (birth) defects

A

drug (antibiotics, pain meds, vaccinations, topical medicines), plant, infection (viral, protozoan, or mycotic), pesticide, radiation
Anything that mother come in contact with

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2
Q

presentation of birth defects

A

can present immediately or will not cause any noticeable signs
Some defects cause abortions

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3
Q

critical period

A

time when organ or organ system is developing

cells are replicating

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4
Q

veratrum californicum

A

false hellebore, corn lily, ingested on day 14 can cause severe defects. cycloptic lamb

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5
Q

Cerebellar hypoplasia

A

underdeveloped cerebellum
Genetic, infectious and toxic
Bovine Viral Diarrhea (BVD) impacting gestation between 100-170 days.
Feline panleukopenia during las 10-14 days of gestation to 10-14 days postnatal

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6
Q

cell restriction

A

increases with differentiation.

Totipotent is least restrictive and non-mitotic functional cells are most restrictive

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7
Q

totipotent

A

zygote can give rise to whole animal

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8
Q

Factors surrounding cell

A

impact gene expression as well as cell contact

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9
Q

Which stage is first occurence of restriction?

A

Morula stage

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10
Q

fates of blastomeres?

A

outer blastomeres become trophoblasts which become placenta, inner blastomeres become inner cell mass

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11
Q

What layer is used for embryonic splitting?

A

inner blastomeres,

makes more individuals

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12
Q

zona pellucida

A

outer layer surrounding the zygote

Stays in place while cell number increases and cell size decreases

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13
Q

gastrulation

A

gives rise to the three germ layers and marks the beginning organ and body development
occurs at about 2 weeks of development
determines polarity of head/tail and right/left

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14
Q

how is the yolk sac different from a chicken yolk

A

yolk sac does not contain as much yolk

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15
Q

layers of bilaminar disc? Which is smaller?

A

Hypoblast is smaller than epiblast

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16
Q

Formation of three germ layers

A

Primitive streak becomes primitive groove.
Epiblast cells flow toward primitive groove. Some do deep to form endoderm, some intermediate to form mesoderm, and some do not go through primitive groove to form ectoderm
Some cells go through primitive node instead to develop notochord by streaming cranial

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17
Q

mesoderm

A

muscle, skeletal tissue, urogenital, and cardiovascular

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18
Q

endoderm

A

lining of the digestive and respiratory tracts plus organs of digestion

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19
Q

ectoderm

A

epidermis, neural tissue and some skeletal//connective tissue of the head

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20
Q

somatic mesoderm

A

give rise to body/body wall

They grow ventrally and meet together to close the body wall/ coelom

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21
Q

splanchnic mesoderm

A

give rise to organs

grows ventrally at smaller radius than the somatic mesoderm to enclose the primitive gut tubeq

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22
Q

schistosomus relexus

A

somatic mesoderm does not close, can survive in utero, but not postnatal
most common in cattle

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23
Q

amorphous globosus

A

free, asymmetrical twin, not sure what causes it

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24
Q

monozygotic twinning

A

identical twinning
3 types:
1. Twinning at 2-4 cell stage, completely separate placentas and blastocysts
2. Morula forms two masses with one trophoblast layer. Shared placenta with separate amniotic cavities
3. Near gastrulation, tow primitive streaks are formed. Shared placental units and shared amnion. Umbilical cords can loop around other twin’s neck.

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25
Q

conjoined twins

A

if masses do not split from two primitive streaks

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26
Q

white matter

A

contains neuroglia and axonic projections

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27
Q

first organ system to initiate differentiation

A

central nervous system

Not the first to become functionally differentiated

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28
Q

Neural tube formation

A

a few days after gastrulation
notochord produces factors that drive ectoderm to form neural plate. Mesoderm and ectoderm rise up to form neural folds while neural groove sinks down between
Neural folds reach out and contact each other. Neural tobe separate from surface ectoderm and descends into embryo. Neural tube cavity joins with amniotic cavity through rostral and caudal neuropore. These close about 1-2 days after cardiovascular system is functional. Issues if no closure.
Closure can be in these stages all along the tube at the same time
Begins in cervical area and progresses in both directions (so abnormal segments can develop between normal segments)

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29
Q

importance of neural tube cavity

A

no cardiovascular system set

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30
Q

neural crest cells

A

separate from surface ectoderm. derived from ectoderm

give rise to ganglia, Schwann cells, and adrenal medulla

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31
Q

alar plate

A

sensory

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32
Q

basal plate

A

motor and autonomics

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33
Q

mantel layer

A

includes alar and basal plates. Neurons in this layer project axons into the marginal layer.

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34
Q

autonomic neruons

A

visceral motor neurons

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35
Q

spinal cord formation

A

alar and basal plates expand in all directions
Alar becomes dorsal horn. Basal becomes ventral horn. Roof and floor plates do not move much, resulting in dorsal sulcus and median fissure

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36
Q

ventral root formation

A

neuronal cell bodies of ventral horn projects axon into the periphery, forming ventral root. The axons from the motor neuron find target.

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37
Q

dorsal root formation

A

cells migrate to ganglion and project axon two ways to target and spinal cord.

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38
Q

functional connection

A

neuron requires functional connection on both ends and become integrated into a system.
More neurons are produced than those that become successful as some do not make functional connection.

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39
Q

positional changes of the spinal cord

A

in early development, spinal cord completely fills vertebral column
sipinal nerves come out of vetebral column and come into contact with bundles of muscle (somites).
Vertebrae grows faster so spinal cord moves relatively cranially, causing spinal nerve roots to elongate. (Need to maintain contact with muscle to survive)

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40
Q

cauda equina

A

many rootlets within spinal column that look like a horse tail

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41
Q

spina bifida

A

caused by tissue with formation of neural tube. Always results in vertebral arch malformation

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42
Q

spina bifida occulta

A

most benign, only effects 1-2 vertebrae

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43
Q

myeloschsis

A

more severe ane neural tube fails to form

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44
Q

meningomyelocele

A

meninges have herniated to where vertebrae should be. Can stand with help. Paresis or Paralysis

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45
Q

3 Primary vesicles

A

Forebrain, midbrain, hindbrain

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46
Q

aqueduct

A

narrower brain cavity

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47
Q

brain malformations

A

cerebellar hypoplasia, anencephaly, lissencephaly, cranium bifidum, hydrocephalus

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48
Q

brain vesicles

A

develops from rostral end of neural tube. Mantle and Marginal layers still present in the wall.

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49
Q

nucleus

A

collection of neuronal cell bodies in the CNS

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50
Q

cerebellar development

A

neurons in external germinal layer undergo a lot of division until they separate from external germinal layer and migrate into cerebellum
As migrating cells descend they integrate with Purkinje neuron axons to make future synaptic junctions

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51
Q

Where are the cells of of the cerebellum derived from?

A

external germinal layer

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52
Q

How do viruses like BVD and feline panleukopenia cause cerebellar hypoplasia?

A

They target external germinal layer, which also causes Purkinje cells to die off.

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53
Q

Where ventricles derived from?

A

central cavity

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54
Q

development of cerebrum and diencephalon

A

cells in mantle layer divide and then are signaled to move through marginal layer to the outside. These cells continue to divide. Then there is a third migration of cells that move farther past this second layer. Cells are forming functional connections and communicating with the cells that have already migrated to make sure it is a good environment.
These migrations are why the grey matter is on the outside of the cerebrum, but inside of the spinal cord and allow for convoluted surface of the brain with sulcus and gyrus

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55
Q

common cause of anencephaly

A

disruption of closing rostral neural pore

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56
Q

lissencephaly

A

smooth cortex, less sulci and gyri, caused by arrested cell migration

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57
Q

encephalocele

A

cranium bifidum, disruption of neural tube formation

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58
Q

hydrocephalus

A

disruption of CSF flow out of brain to subarachnoid space from choroid plexus

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59
Q

posterior pituitary gland development

A

neuronal cell body in brain projects axon to the posterior pituitary.
Direct growth from floor plate to forebrain.

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60
Q

anterior pituitary gland development

A

For anterior pituitary, the axon goes to portal vein and releases neural substance that is carried to anterior pituitary through this vein. Upgrowth from roof of primitive mouth.

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61
Q

What germ layer gives rise to pituitary glands?

A

Both are from ectoderm

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62
Q

Adult heart organization

A
  1. atria are beside each other and dorsal to the ventricles
  2. Ventricles are beside each other
  3. Configuration of the outflow: spiral around each other
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63
Q

Heart embryology

A

1st organ to functionally differentiate, first beats around the time of neural tube closure (18-19 days in dog, 35-38 hours in chick)
Moves blood from extra embryonic vessels through embryonic circulatory system

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64
Q

stages of heart development

A

cardiogenic plate, single median heart tube, the heart starts, cardiac loop, partitioning and valves

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65
Q

friquency of congenital cardiovascular anomaly in humans

A

8/1000 human births

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66
Q

development and folding of cardiogenic plate

A

begins development outside the embryo then brought in through 180 degree body wall folding and closure, goes to about where mandible would be in adult

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67
Q

when does heart beat start?

A

Fusing of endocardial heart tubes begins the heart beat from caudal to cranial with contractions

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68
Q

derivitives of truncus arteriosus and blubus cordis

A

ascending aorta and pulmonary trunk

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69
Q

bulbus cordis

A

part of the right (conus arteriosus) and small part of left ventricle

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70
Q

Primitive heart regions

A

truncus arteriosus and bulbus cordis, ventricle, atrium (becomes right and left atria), sinus venosus
Differential growth with no internal divisions

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71
Q

derivatives of sinus venosus

A

left coronary sinus, part of wall of the right atrium

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72
Q

cardiac loop

A

normal bending to the right caused by asymmetries in proliferative activity (differential growth)
allows bulbus cordis to lie next to the ventricle because this is where it contributes
By the end, atrium is dorsal to ventricle

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73
Q

atrioventricular canal partitioning

A

endocardial cushions divide the atrioventricular canal

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74
Q

atrial partitioning

A

development of 2 septa and 3 foramina
need to maintain right to left shunting of blood in the atrium then stop this shunting postnatally
Blood flow from right atrium, inbetween septum 2 then 1 through foramen ovale, to left atrium

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75
Q

first septum development

A

from dorsal part of atria to endocardial cushions and closing foramen 1

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76
Q

first foramen

A

opening between endocardial cushions and septum 1

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77
Q

second formamen

A

develops as foramen 1 closes to maintain shunting. Develops by apoptosis of semtum 1

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78
Q

second septum

A

develops ventral caudal along with foramin 3 (foramen ovale)

79
Q

partitioning of truncus arteriosus and bulbus cordis

A

outflow separation between aorta and pulmonary trunk by spiral septum
Truncus arteriosus gives rise to majority of aorta and pulmonary trunk with some contribution from bulbus cordis
Cushions invade lumen of truncus arteriosus and grow together. Different orientations results

80
Q

ventricular partitining

A

endocardial cushion grows down while interventricular septum grows upward and spiral septum seals interventricular foramen
There is still a foramen in the interventricular septum
One part of spiral septum fuses with interventricular septum and another part fuses with the partitioning of the atrioventricular canal

81
Q

Dextrocardia

A

folding has been flipped around, so the right ventricle looks like the left and so on

82
Q

situs inversus

A

entire body plan is flipped. Doesn’t impact life. 1/10,000 humans.

83
Q

Ectopic cordes

A

heart is outside the thoracic cavity either by being cranial to first rib or ventral to sternebra. Was not folded in correctly. Most commonly found in cattle

84
Q

valvular defects

A

stenosis/narrow valve, insufficiency (valve did not form correctly and is leaking and blood can bypass it), dysplasia (abnormal development)

85
Q

Tetralogy of Fallot

A

Intraventricular septal defect, pulmonary stenosis, dextroposition of aorta (overriding), right ventricular hypertrophy
due to uneven division of truncus arteriosus in spiral septum formation, resulting in uneven intraventricular septum formation.
Right ventricle is exposed to the higher pressures of the left ventricle and hypertrophies

86
Q

pulmonary stenosis

A

narrowing of pulmonary trunk, aorta overrides right and left ventricular outputs

87
Q

What facilitates the fetus to pump blood to the placenta?

A

Coupling the systemic outputs by having the ventricles by next to one another

88
Q

fetus vs embryo

A

with a fetus, the species can be identified but not in an embryo

89
Q

closure of umbilical arteries

A

dam chews off the umbilicus

90
Q

closure of umbilical vein

A

due to loss of blood pressure and less prostaglandin E2

91
Q

Fetal circulation

A

Umbilical vein carries oxygenated blood from placenta to liver. Here it either goes through tissue of liver to caudal vena cava, or go through shunt to bypass parenchyma of liver to cauda vena cava. Blood is now purple because it is mixing with low O2 blood in CVC.
1st route from CVC: through oval foramen between septa 1 &2 to left atrium then left ventricle and aorta.
2nd route: goes to right ventricle mixes with more low O2 blood from cranial vena cava and goes to pulmonary trunk.
Ductus arteriosus joins blood from pulmonary trunk with aorta.
Aorta descends into umbilical arteries.

92
Q

which has more oxygen? umbilical vein or umbilical artery?

A

umbilical vein

93
Q

closure of ductus venosus

A

usually before birth, but can also close due to changes in blood pressure and less prostaglandin E2

94
Q

closure of oval foramen

A

left atrium has lower blood pressure than right atrium in vivo because right atrium is receiving more blood, As lungs expand the pressure on the left increases and right decreases because there is less placental return, pushing septum 1 into septum 2

95
Q

closure of ductus arteriosis

A

drop in blood pressure and less prostaglandin E2, takes the longest to close, starting at birth to about 1-2 days after

96
Q

prostaglandin E2

A

vasodilator

97
Q

aorta in embryo

A

goes from 2 ventral and 2 dorsal aorta to one of each

98
Q

5th aortic arch

A

only present in lower vertebrates

99
Q

formation/ degeneration of aortic arches

A

Form sequential, 1st arch degenerates, dorsal aorta between arches 3 and 4 degenerate, making the 3rd responsible for head and 4th responsible for the body

100
Q

derivatives of 3rd aortic arch

A

right and left internal carotid arteries

101
Q

left 4th aortic arch

A

aortic arch in adult

102
Q

right 4th aortic arch

A

right subclavian artery

103
Q

left 6th aortic arch

A

ductus arteriosus

104
Q

right 6th aortic arch

A

degenerates. Why? right side needs to have continuation of developing GI system

105
Q

aortic coarctiation

A

constriction of developing aortic arch resulting in malformation

106
Q

ligamentum arteriosum

A

adult remnant of ductus arteriosus

107
Q

left 4th aortic arch becomes adult arch, left 6th aortic arch becomes ductus arteriosus

A

normal

108
Q

right 4th aortic arch becomes adult arch, right 6th aortic arch becomes ductus arteriosus

A

right to right connection and animal can function normally

109
Q

right 4th aortic arch becomes adult arch, left 6th aortic arch becomes ductus arteriosis

A

normal function during suckling phase, but issues with solid food because vessels are wrapping around the esophagus and food cannot pass through

110
Q

urogenital ridge

A

forms urinary and reproductive system, made from intermediate mesoderm and coelomic mesothelium

111
Q

Which early kidney becomes adult kidney?

A

Metanephros, but there is remnants of pronephros and mesonephros

112
Q

pronephros

A

7-8 tubules, non-functional, pronephric duct persists as the mesonephric duct, develops in cervical area/ embryologic neck

113
Q

mesonephros

A

consists of 70-80 tubules, tubules
look similar to pronephric tubules, have glomerulus at one end connected to the mesonephric duct at the other, rapidly degenerates from cranial to caudal

114
Q

derivatives of caudal tubules of mesonephros

A

caudal tubules and duct remain to form testicular channels, epididymis, ductus deferens and contributes to gonad development in both sexes

115
Q

metanephros

A

adult kidney, consists of metanephric diverticulum (ureteric bud) and metanephrogenic mass (mesenchyme). Metanephric diverticulum come off mesonephric duct and continues as the metanephrogenic mass

116
Q

derivatives of metanephric diverticulum

A

ureter, renal pelvis, calyxes and collecting ducts

117
Q

derivatives of metanephrogenic mass

A

nephrons: functional unit of kidney that produce urine. Production stops just before or just after birth and never restarts. Cannot be replaced in adult, lost with age

118
Q

variation in macroscopic apearance

A

unfused lobes in cow

variation resulting from interactions between metanephric diverticulum and metanephrogenic mass

119
Q

development of urinary bladder

A

Urinary bladder develops from expansion of the urachus and cranial end of the urogenital sinus

120
Q

urogenital sinus

A

cranial portion forms bladder along with urachus

Caudal portion forms pelvic and penile urethra in male, and pelvic urethra, vestibule and caudal vagina in female

121
Q

Duct incorporation and reorganization

A

metanephric diverticulum starts out not opening into the bladder, then bladder grows dorsally to incorporate these tubules so that mesonephric duct which becomes ductus deferens opens closer to the urethra and ureter opens into the bladder.
This swapping results in the trigone region

122
Q

urachus

A

channel from cranial urinary bladder down the allantoic stalk that opens into the allantoic cavity. Closes around time of birth

123
Q

renal agenesis

A

kidney fails to develop

124
Q

renal dysplasia

A

abnormal growth, eg. Horseshoe kidney

125
Q

renal hypoplasia

A

kidney does not develop to full size

126
Q

ectopic kidneys

A

normally, differential growth moves kidney from pelvis to sublumbar location.
ectopic kidneys remain in pelvis
doesn’t result in many issues until animal might become pregnant, putting a lot of stress on the kidney

127
Q

patent urachus

A

urachus does not degenerate, increased risk of umbilical infections

128
Q

Why is the urachus needed?

A

there is a membrane covering the urogenital sinus to prevent urine from leaving into amniotic cavity
Later this membrane breaks down and urine can leave into allantoic and amniotic cavities

129
Q

early reproductive development

A

mesonephric duct is retained in the male, paramesonephric duct associated with female development
gonad and external genitalia are able to develop into either sex at this point

130
Q

hormones in male differentiation

A

Testis produces Mullerian inhibiting substance from sertoli cell to suppress paramesonephric duct and testosterone from leydig cells so mesonephric duct is stimulated to form ductus deferens and epididymis. Testis also produces dihydrotestosterone that stimulates external genitalia to produce penis, scrotum, prostate, seminal vesicle, and bulbourethral gland

131
Q

hormones in female differentiation

A

ovary produces estrogens, including from maternal and placental sources to stimulate paramesonephric duct to form uterine tube, uterine horn, body, cervix, and cranial portion of vagina, and stimulates external genitalia to form labia, clitoris, and caudal portion of vagina

132
Q

Primordial germ cells

A

develop in caudal portion of yolk sac, population of 100-300 cells. Then they migrate through hindgut and messentey to form genital ridge immediately ventral to mesonephros

133
Q

genital ridge

A

primordial germ cells undergo replications.

134
Q

gonadal cords

A

formed by disintegrating mesonephric tubule epithelium and primordial germ cells form seminiferous tubules

135
Q

efferent ductules

A

small sperm conducting parts of testicle

136
Q

formation of testis

A

rete testis and efferent ductules are derived from mesonephric tubule.
Mesonephric duct becomes ductus deferens and epididymis

137
Q

Gubernaculum

A 
mesenchymal tissue (embryologic connective tissue) between the testicle and scrotum. 
Influences extracellular matrix to produce hyaluronic acid to increase water and well to dilate inguinal canal and scrotum. Mesenchymal cells then decrease hyaluronic acid and water to make gubernaculum shrink and pull testicle into the scrotum
Tethers the testicle in location. Becomes ligament of the tail of the epididymis and the proper ligament of the testes
138
Q

ovarian development

A

gonadal cords break down to surround oocyte to form follicular cells
Ended by birth

139
Q

variation in uterine morphology

A

due to differing fusion of paramesonephric ducts

140
Q

uterus didelphys

A

No fusion between paramesonephric ducts, 2 uteruses and vaginal cavities, normal in marsupials

141
Q

vagina simplex uterus duplex

A

some fusion of paramesonephric ducts, rabbits and rodents, two uteruses and two cervixes, one vagina/ vaginal cavity

142
Q

uterus bicornis

A

2 uterine horns with a fused body cranial to singular cervix, one vagina

143
Q

is the cervix considered a part of the vaginal cavity, uterus, or neither?

A

uterus

144
Q

Which animal has the greatest degree of paramesonephric duct fusion in domestic animals?

A

Horse

145
Q

primate uterus

A

completely fused paramesonephric ducts with just a uterine body

146
Q

urogenital folds

A

help form ventral aspect of penile part of male urethra and labia of the vulva in female

147
Q

labioscrotal swellings

A

give rise to labia majora in human females, which is not present in domestic animals.
Gives rise to scrotum in male

148
Q

erectile tissue

A

corpora cavernosa and corpus spongiosum in male penis, corpora cavernosa in female clitoris

149
Q

genital tubercle

A

forms Glans clitoris or penis, erectile tissue and the bulb of the vaginal vestibule

150
Q

cloaca

A

sewer, present in non mammals after birth
closed by cloacal membrane
Urorectal septum forms at junction of hindgut and urogenital sinus to divide the cloaca. Grows caudally and divides cloacal membrane into anal membrane and urogenital membrane, which both break down in normal development

151
Q

anogenital distance

A

distance between anus and glans, this is shorter in the female

152
Q

malformation of genitalia

A

Hypoplasia or aplasia: few or no germ cell, respectively
Cryptorchidism: interruption of testicular descent, retained testicle, could be one side or bilateral
Stenosis (narrowing) of ducts and abnormal fusion.
Hypospadia: open urethra, penile part of male urethra does not close, incorrect formation between urogenital sinus and urogenital folds.
Intersex conditions

153
Q

testicular feminization

A

not uncommon in pigs, XY chromosome but not enough testosterone produced in utero to cause differentiation or testosterone receptors are defective, anogenital distance is increased compared to female

154
Q

Does male or female differentiation occur earlier?

A

male differentiation beginning with paramesonephric duct

155
Q

Fee martin

A

Most commonly in cattle, dizygotic twins with one male and one female
Blood supplies of developing twins join together 95% of the time and hormones pass between. Female is most severely impacted because male differentiation begins first. Derivatives of paramesonephric duct are impacted the most.

156
Q

Foregut fermenter

A

ruminants, stomach (rumen) is greatly enlarged. Microbial fermentation takes place in non glandular chambers, abomasum is glandular. Still some fermentation in hindgut.

157
Q

which section of the GI tract is enlongated in horse?

A

ascending colon

158
Q

spiral colon

A

ascending colon of ruminant,

also found in swine but with different physiology between large ruminants, small ruminants and swine.

159
Q

Foregut derivatives

A

esophagus, stomach, descending duodenum, liver, and pancreas

160
Q

midgut derivatives

A

ascending duodenum, jejunum, ileum, cecum, ascending and transverse colon

161
Q

hindgut derivatives

A

descending colon

162
Q

simple stomach

A

differential growth of the dorsal wall
90 degree rotation around the longitudinal axis of the dorsal portion to the left (anticlockwise)
Rotation around a dorsoventral axis: caudal end of the stomach shifts to the right and cranially
In embryo: straight tube from mouth to cloaca. Dorsal wall grows fastest, causing the rotation

163
Q

directionality of GI tract

A

descending duodenum is always on the right fundic part of stomach projects to the left

164
Q

mesenteries

A

all organs supported by mesentery in early development

Dorsal mesogastrum/greater omentum grows to allow rotation of gut during development

165
Q

Which mesentery elongates to allow for rotations of the stomach?

A

dorsal mesentery, ventral does not elongate

Dorsal mesentery folds in on itself to create 2 leaves of greater omentum

166
Q

ruminant stomach

A

rumen develops as an expansion of the fundus. Project to left body wall.
reticulum is cranioventral pocket of developing rumen. Also on the left
Omasum develops as a bulge along the lesser curvature, projects to right body wall.
Abomasum is the remainder of the stomach, location is variable

167
Q

development of midgut

A

supported by elongated dorsal mesentery and cranial mesenteric artery
Cecum forms as evagination of caudal limb of loop
Loops towards umbilicus and yolk sac, herniates into the yok sac because the liver is so large during development

168
Q

Flow of ingesta in intestines

A

in caudal duodenal flexure, injesta flows from right to left caudal to mesenteric root. In transverse colon, ingesta flows from right to left cranial to mesenteric root

169
Q

rotation of intestines

A

occurs in physiologic hernia, stomach has already undergone its rotation.
Cranial limb undergoes explosive growth and passes to the right of cranial mesenteric artery. Pushes the caudal limb cranially. Growth of cranial limb continues in cranial direction, moving caudal limb to the right side. Herniated viscera drawn back into body cavity. Ends with 270 degree rotation around cranial mesenteric artery forming mesenteric root.

170
Q

intestinal stenosis

A

narrowing of intestinal lumen due to narrowing during recaulization when it should expand

171
Q

intestinal atresia

A

during twisting of intestine, part of blood supply become compromised resulting in missing section

172
Q

atresia ani

A

anal membrane does not break down

173
Q

urorectal fistula

A

issue in separating urogenital sinus from rectum and anal canal

174
Q

Both atresia and urorectal fistula

A

defecation through the vulva, increased risk of urinary tract infection

175
Q

basic elements of pharyngeal arches

A

aortic arch, cartilage rod, cranial nerve and muscle

176
Q

structures derived from pharyngeal arches

A

face, mandible, maxilla, larynx, hyoid apparatus

177
Q

Which is more? cranial nerves, or pharyngeal arches?

A

cranial nerves

178
Q

1st pharyngeal arch

A

becomes trigeminal nerve (CN V), mandible, maxilla, incus, and malleus bones, muscles of mastication and rostral digastricus

179
Q

2nd pharyngeal arch

A

becomes facial nerve (CN VII), hyoid and stapes bones, muscles of facial expression and caudal digastricus

180
Q

3rd pharyngeal arch (FYI)

A

Glossopharyngeal nerve (CN IX), stylopharyngeus: dilator of pharynx

181
Q

4th and 6th pharyngeal arches

A

CN X, Vagus nerve, laryngeal cartilage, 4th become cricothyroideus muscle and 6thh the remaining intrinsic laryngeal muscles

182
Q

Where do the right and left recurrent laryngeal nerves turn around in the body?

A

Right around the right subclavian artery, left around the ligamentum arteriosum

183
Q

nasal pit

A

depression that becomes nasal cavity

184
Q

cleft lip

A

failure to close fissure between medial nasal process and maxillary process

185
Q

oronasal cavity formation

A

oral and nasal cavities are freely communicating through oronasal cavity. Oronasal membrane breaks down. Nasal pits excavate caudally as well as medially to connect together. Primary palate forms from maxillary process to separate oral and nasal cavities and right and left nasal cavities.

186
Q

oronasal cavity separation

A

abnormally large tongue regresses in size so secondary palate can have more horizontal orientation and grow together. This is a small time window, so if it doesn’t close now, it stays open as cleft palate.
Nasal septum needs to grow down to contact secondary palate to separate right and left.
Secondary palates need to fuse with each other, as well as close primary palate.
Rostral 2/3 is soft membranous right after closure, then ossifies into hard palate.

187
Q

prognosis for cleft palate

A

difficult to manage with higher incidence of pneumonia, so euthanized.

188
Q

respiratory morphogenesis

A

esophageal and tracheal separation, Laryngotracheal groove is in ventral pharynx between pharyngeal arches 4 and 6. Trachea is being pinched off ventral part of esophagus
Sometimes separation does not occur

189
Q

lung development

A

alveoli are late developing structure. Greatest percentage develop in postnatal period.

190
Q

Why are there respiratory movements in utero?

A

If joint doesn’t move in development, it won’t move after birth. Also exercising respiratory muscles. These movements involve inhaling amniotic fluid that is expelled through lymphatics and capillaries

191
Q

Pulmonary transition to postnatal life

A

during birth, need to expel amniotic fluid from lungs, and start breathing through gas exchange. Relies on normal presentation.
Once on the ground, the umbilical connection is lost and the lungs and alveoli need to expand to increase surface area for gas exchange and get rid of fluid.
Note: hanging animal by rear legs hinders expansion of lungs.

192
Q

pulmonary hypoplasia

A

abnormal structure of pleural cavity

193
Q

trachel hypoplasia

A

underdeveloped trachea, common in brachycephalic breeds

194
Q

tracheoesophageal fistulas

A

connection between esophagus to trachea

histo final exam extravaganza! (9 decks)

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