Lecture 3 Flashcards
1
Q
nondisjunction
A
error in cell division
- failure of chromosomal pair or 2 chromatids to disjoin
- may occur in maternal or paternal gametogenesis
2
Q
down syndrome (trisomy 21)
A
- extra copy of chromosome 21
- decreased alpha fetoprotein (AFP) levels
- error during meiotic division
- varying levels of mental retardation, craniofacial anomalies, cardiac defects, hypotonia, early onset of Alzheimer’s disease
3
Q
alpha fetoprotein (AFP)
A
plasma protein produced by the old sac and the liver during fetal life
-though to be a fetal counterpart of serum albumin
4
Q
menstrual phase
A
day 1-4, the functional layer is sloughed off
5
Q
proliferative phase
A
day 5-14, the functional layer becomes thicker
6
Q
secretory phase
A
day 15-28, the functional layer is very thick, the glands are filled with glycogen
7
Q
ovulation days
A
~day 14-15
8
Q
2 functions of the ovaries
A
- oogenesis- production of oocytes (female gamete)
- steroidogenesis- hormone production (estrogen and progesterone)
9
Q
2 major events happening in the ovary
A
- maturation of the follicle
- maturation of the oocyte
10
Q
what structures are ovulated on day 14?
A
- oocyte
- zona pellicida- glycoprotein structure surrounding the oocyte
- corona radiata- specialized cells of the ovarian follicle that surround the zona pellucida
11
Q
what gives rise to the corpus luteum?
A
granolas cells that stay in the ovary
12
Q
two systems for dating pregnancies?
A
- fertilization age
- menstrual age
13
Q
fertilization age
A
dates pregnancy from the time of fertilization
14
Q
menstrual age
A
dates pregnancy from the woman’s last normal menstrual period.
- the menstrual age of a human embryo is 2 weeks greater than the fertilization age because usually 2 weeks elapse between the start of the last menstrual period and fertilization
15
Q
fertilization age pregnancy division
A
- period of early embryo (3 weeks)
- period of embryonic organogenesis (8 weeks)
- fetal period (38 weeks)
16
Q
menstrual age pregnancy division
A
3 equally dated trimesters
17
Q
major events of week 1
A
- cleavage divisions produce smaller daughter cells
- the morula enters the uterus
- zona pellucid breaks down and a central cavity is formed (blastocele)
- developing embryo is called a blastocyst
18
Q
embryoblast
A
development of embryo
19
Q
trophoblast
A
involved in maintenance
20
Q
once the blastocyst attached to the endometrial epithelium the endometrium changes in the following ways
A
- arteries become elongated and coiled
- uterine glands secrete nutrients (glycogen)
- stromal cells become large and filled with glycogen and lipids
21
Q
implantation induced the trophoblast to proliferate into
A
- cytotrophoblast
- syncytiotrophoblast
22
Q
cytotrophoblast layer
A
mitotically active, inner layer of cells
23
Q
syncytiotrophoblast layer
A
- many functions
- always adjacent to maternal blood supply
- produces human chorionic gonadotropin (hCG)
24
Q
at the end of weeks 1
A
- the endometrium has proliferated and is full of blood vessels and glands
- the developing embryo is 7 days post fertilization and has begun migrating into the endometrium (implantation)
25
what is the period of maximal sensitivity to abnormal development of an embryo
3-8 weeks
embryonic period
-susceptibility to teratogens
-tissues and organs are forming and development of a system can be severely impacted
26
teratogens
environmental agents that cause congenital abnormalities
27
most ectopic pregnancies occur in the ...
uterine tube/ oviduct
28
lithopedion
- occurs in less than 2% of pregnancies
- results from undiagnosed advanced abdominal pregnancy
- embryo can grow to fetal size then calcifies
- 40 year old presents with abdominal pain and features of acute intestinal obstruction
29
complete hydatidiform mole
- fertilization of an empty oocyte by 1 or 2 sperm
| - fetus is entirely missing
30
partial hydatidifrom mole
- oocyte inseminated by 2 sperm
- female pronucleus and 2 male pronuclei combine to form triploid nucleus
- evidence of embryonic development usually found
31
clinical presentations of partial hydatidiform mole
- abnormally high levels of plasma hCG
- severe nausea and vomiting
- vaginal bleeding
- spontaneous abortion
32
during week 2 embryo blast reorganize into 2 epithelial layers
- epiblast layer
| - hypoblast layer
33
epiblast layer
-high, columnar cells related to the amniotic cavity
34
hypoblast layer
small cuboidal cells adjacent to the yolk sac
35
2 cavities that from during week 2
- amniotic cavity
| - primative yolk sac/umbilical vesicle
36
extraembryonic mesoderm
layer of loose connective tissue that forms between the yolk sac and the cytotrophoblast
37
chorionic cavity
space formed when the cavities of the extra embryonic mesoderm become confluent and divides the extra embryonic mesoderm into the
- extraemrbyonic somatic mesoderm
- extraembryonic splanchnic mesoder
38
extraembryonic somatic mesoderm
lining trophoblast and the amnion
39
extraembryonic splanchnic mesoderm
lines the yolk sac
40
3 layers of the chorion
- extraembryonic somatic mesoderm
- cytotrophoblast layer
- syncytiotrophoblast layer
41
connecting stalk
future umbilical cord that suspends the amniotic cavity and yolk sac in the chronic cavity
42
functions of the placenta
- protection and nutrition
- respiration and excretion
- hormone production
43
sources of amniotic fluid
- amnion cells
- maternal tissue
- fetal urine
44
what is oligohydramnios
-disorder of low volumes of amniotic fluid <500ml
45
what causes oligohydramnios
-placental insufficiency with diminished placental blood flow (renal agenesis or obstructive uropathy)
46
complications of oligohydramnios
-pulmonary hypoplasia, facial defects and limb defects, compression of umbilical cord
47
what is polyhydramnios
-disorder of high volumes of amniotic fluid >2000ml
48
what causes polyhydramnios
- fetus does not swallow the usual amount of amniotic fluid
- esophageal atresia
- many cases are idiopathic
49
complications of polyhydramnios
- premature rupture of membranes/ premature birth
| - IUGR (intra- uterine growth restriction)
50
major event of week 3
gastrulation
51
primitive streak
formed in week 3 when epiblast cells become motile and converge on the midline of the dorsal disc
52
primitive groove
serves as an opening for cells to migrate ventrally
53
primitive node
thickening at the end of the primitive streak
54
endoderm
formed by epiblast cells that replace the entire hypoblast layer
55
mesoderm
formed by epiblast cells that migrate between existing layers
56
ectoderm
formed by cells that remain in the epiblast after gastrulation is complete
57
when does the primitive streak disappear
by the end of week 4
58
sacrococcygeal teratoma
- remnants of the primitive streak persist in the sacrococcygeal area
- cells in the streak proliferate and form a tumor
- often contain tissues of all 3 germ layers
- most common newborn tumor
59
notochord develops from..and it
- migrating mesoderm cells
| - underlies the neural tube and serves as the basis for the axial skeleton
60
neural tube closure occurs first in the ...
cranial neuropore and then 2 days later in the caudal
61
how does the neural tube close
the neural folds elevate, grow closer to the other and eventually fuse
62
spina bifida occulta
typically asymptomatic, identified by dimple or tuft of hair
(oculta..)
63
spina bifida with meningocele
fura mater missing in the area of the defect, with arachnoid layer bulging beneath the skin
64
spina bifida with meningomyelocele
severe neurological defects below the level of the lesion
65
myeloschisis
nuerofolds fail to fuse -- most severe
66
meroanencephaly
- failure of the rostral neuropore to closer during the 4th week
- forebrain development is abnormal
- some or all of the brain stem is intact
- overlying bone is defective (calvaria)
67
derivatives of surface ectoderm
- epidermis
- nails
- hair
- substaneous glands
- mammary glands
- anterior pituitary
- enamel
- lens of eye
68
derivatives of neural ectoderm
- CNS
- retina
- posterior pituitary gland
- pineal body
69
neural crest cells
- derived from ectoderm
- 4th germ layer
- migrate form their site of origin
- very vulnerable
- undergo ectodermal to mesenchymal differentiation
70
paraxial mesoderm
- bilateral mesoderm next to the neural tube
- organized into somitomers in the head region
- caudally smoothers organize into somites
- age of the embryo is correlated to the number of somites
- each somite forms its own sclerotome, myotome and dermatome
71
sclerotome
axial skeleton
72
dermatome
dermis of the back
73
myotome
developing muscular system: myotome regions of somite that give rise to skeletal muscles
74
intermediate mesoderm
- gives rise to urogenital system
| - functionally divided into urinary system and genital system
75
lateral plate mesoderm
epithelium lining the cavity (mesothelium)
| -somatic mesoderm and splanchnic mesoderm
76
somatic mesoderm
with the overlying ectoderm will form the body wall
77
splanchnic mesoderm
with the underlying endoderm will form the gut wall
78
body folding occurs in 2 planes
- longitudinal or medial plane (cranial- caudal)
| - horizontal plate (lateral body folding)
79
cranial fold/ head folding
- septum transversum
- primordial heart
- pericardial cavity
- oropharyngeal membrane
- froms the foregut
80
tail folding
- primitive streak
- cloacal membrane
- connecting stalk
- forms the hindgut
81
lateral folding (growth of somites)
- forms body wall
| - forms the midgut
82
endoderm is folded into the body cavity and gives rise to
- pharyngeal foregut epithelium
- foregut proper epithelium
- respiratory epithelium
- midgut epithelium
- hindgut epithelium
- glands of the respiratory and digestive system
83
splanchnic mesoderm forms
the muscle and connective tissue layers, blood vessels and peritoneal components
84
omphalocele
- failure of the intestines to return to the body cavity
- covered by amnion
- often associated with other malformations
85
gastroschisis
- protrusion of the viscera into the amniotic cavity due to abnormal closure of the body wall
- viscera are not covered by amnion
86
Meckel's diverticulum
- most common congenital defect of the GI system
- due to persistence of the vitalize duct
- anti-mesenteric border of the ileum
- typically no symptoms
- may contain ectopic gastric or pancreatic mucosa
87
osteoclasts originate from
blood cells derived monocytes
88
osteocytes, osteoblasts, bone lining cells, osteoprogenitor cells originate from
mesenchymal stem cell
89
mesodermal cells give rise to
mesenchyme (embryonic connective tissue)
90
neural crest cells give rise to
ectomesenchyme
91
embryological sources of bone are
- paraxial mesoderm
- lateral plate somatic mesoderm
- neural crest cells
92
paraxial mesoderm in bone development
sclerotome forms the majority of the axial skeleton
- vertebral column
- ribs
- base of the skull
93
cells of the sclerotome form..
the vertebral body and the annulus fibrosus of the intervertebral disc
94
the notochondral cells enclosed y the sclerotome ...
form the nucleus pulpous of the disc
95
lateral plate somatic mesoderm in bone development
forms
- the bones of the limbs
- sternum
- pelvic girdle
- shoulder girdle
96
neural crest cells in bone development
they have a critical role in the development of the face
