1.4 Morphological and functional development of the fetus Flashcards
is the time elapsed since last menstrual period
Menstrual Age/ Gestational Age
time for ovulation used by embryologists
Ovulation/Post concepetion/Fertilization Age
divides the period of gestation into 3 units of calendar months
Trimesters
4 important events at the 1st 2 weeks of life
Ovulation
Fertilization
Blastocyst formation
Implantation
Where does fertilization occur?
Ampulla of Fallopian tube
4 possible results of (+) PT
- Unembryonic
- Blighted
- Ectopic
- Normal pregnancy
the term used for a conception between 3rd week to before 8th week
Embryo
lenth of chorionic sac at 3rd week after ovulation (5th gestational age)
1 cm
features at 5th week of gestation
formed embryonic disc
(+) PT
body stalk differentiated
4th week after ovulation, what are the developments?
Heart and pericardium prominent detectable pulsation arm/leg buds present body stalk is now an umbilical cord Embryo: 4-5mm in length Chorionic sac: 2-3 cm in daimeter
when are the following observable:
Head bigger than the trunk
Fingers/toes present
6th week after ovulation/8th Gestational Age
what is the length of the embryo by 6th week after ovulation/8th Gestational Age?
22-24mm
the term used for a product of conception from 8 weeks until birth
Fetus
the length of fetus at 8 weeks
4cm
uterus palpable at the level of the symphysis pubis @ what age?
12th gestational week
earliest time possible for the OB-GYN to detect the sex of the fetus
12th gestational week
the age of gestation when by Ultrasound, the fetus is echogenic and appear white
12 weeks
CRL (crown-rump Length) @ 12 weeks?
6-7 cm
describe the fetus @ 16 weeks as to:
CRL
Weight
Fundus palpable region
CRL: 12 cm
Weight: 110g
Fundus palpable region: between symphysis pubis and umbilicus
when is the midpoint of pregnancy?
20 weeks (no longer an abortus)
fundus is palpable where @ 20 weeks
level of umbilicus
what is the weight of the fetus @ 20 wks?
300g
weight of the fetus by 24 weeks
630g
when do eyebrows and eyelashes start to appear in a fetus?
24th week (gestational)
describe the fetus at 28th week as to:
CRL
Weight
CRL: 25cm
Weight: 1100g
what is covering the skin of the fetus at 28th week of gestation?
Vernix caseosa
T/F. as long as the skin of the fetus is no longer transparent, the infant can survive if born.
True. but with expert care
What is the CRL of a fetus @:
32 weeks
36 weeks
40 weeks
32 weeks: 28 cm
36 weeks: 32 cm
40 weeks: 36 cm
what is the fetal weight at the following weeks:
32 weeks
36 weeks
40 weeks
32 weeks: 1800 g
36 weeks: 2500 g
40 weeks: 3400 g
average diameter of the pelvis
10 cm
what is a contracted pelvic?
pelvis with a diameter of <8cm
what are the 5 skull bones? (identify paired/unpaired)
2 Parietal 2 Frontal 2 Temporal 1 Occipital 2 Wings of sphenoid
membranous spaces separating skull bones
Sutures
define the suture:
between 2 frontals
Frontal suture
define the suture:
either side between the inferior margin of the parietal bone and upper margin of the temporal bone
Temporal Suture
define the suture:
between frontal and parietal bones
coronal suture
define the suture:
between the post.margin of parietal bone and upper margin of occipital bone
Lambdoid suture
an irregular space where several sutures meet and is enclosed by a membrane
Fontanel
What are the 3 fontanels?
Greater/anterior
Lesser/posterior
Temporal/Casserian
the head circumference with greatest length
Occipitofrontal (11.5 cm)
ideal diameter for vaginal delivery is 9.5cm which is the measurement of what head circumference?
Biparietal (9.5 cm)
the head circumference that is flexed at birth for delivery
Suboccipetobregmatic (9.5 cm)
adaptation of the fetal skull to the maternal pelvis
Molding
it functions as the lungs, GIT, kidneys for the fetus. what is the normal volume?
Chorionic villi + Intervillous space (140ml at term)
Primary biological compartment of the maternal transfer
Intervillous space
volume of Uteroplacental blood flow
700ml-900ml
histologic barriers of the placental transfer (3)
Syncytiotrophoblast
Stroma of intervillous space
Fetal capillary wall
Type/modes of placental transfer
Diffusion
Selective transfer & Facilitated diffusion
Specific receptor mediated mechanisms
What type of placental transfer>
a) Anesthetic gases
b) Iron
c) Vitamin C
d) IgG
a) Diffusion
b) Selective transfer & Facilitated diffusion
c) Selective transfer & Facilitated diffusion
d) Specific receptor mediated mechanisms
the major nutrient of fetal growth
Glucose
anultrafiltrate of plasma in early pregnancy
Amniotic fluid
describe amniotic fluid @: Early pregnancy 4 months 2nd trimester 20 weeks
Early pregnancy: amniotic fluid from amniotic membrane
4 months: fetus facilitates in amniotic fluid (swallowing, respiring)
2nd trimester: reflects composition of fetal plasma
20 weeks: amniotic fluid composed of fetal urine
when do fetal kidneys start producing urine?
12 weeks
describe the volume changes in amniotic fluid
@ 8 weeks: volume increase by 10mL/ week
@ 21 weeks: increase by 60mL/week
@ 33 weeks: decrease back to a steady state
Define the terms:
oligihydramnios
polyhydramnios
oligihydramnios: <500mL of amniotic fluid @ term
polyhydramnios: 2000mL of amniotic fluid @ term
7 functions of the Amniotic fluid
- Physical protection
- Lung expansion
- EGF
- PTH-rP
- Musculoskeletal development
- Maintain even temperature
- Cervical dilator @ labor
3 shunts present at the fetal circulation
Ductus venosus
Foramen ovale
Ductud Arteriosus
Umbilical Vein
functionally close at:
Physically close at:
functionally close at: 0-96 hrs
Physically close at: 2-3 weeks
atrophied and obliterated umbilical artery forms the
Umbilical ligament
Intra-abdominal remnant of the umbilical vein
Ligamentum Teres
constricted ductus venosus
Ligamentum venosum
Site of hemopoiesis @ 0-12 weeks
Yolk sac (mesoblastic)
Site of hemopoiesis @ 16 weeks
Liver, Spleen (hepatic)
the volume of the fetoplacental volume at term
125ml/Kg
Hemoglobin-globin differences from the adult (3)
Primitive forms
HgF
HgA
when does a fetus start to produce procoagulants, fibrinolytic and anticoagulant proteins
12 weeks
fetal fibrinogen appears at
5 weeks
IgG is transported to the placenta ___. the bulk is acquired at _______. adult values are obtained at _____.
16 weeks
last 4 weeks of pregnancy
3 years of age
spinal cord extends at these during?
S1
L3
L1
S1: 24 weeks
L3: Birth
L1: adult
persitalsis appears @
11 week
fetus absorbs water from swallowed amnion @
16th week
how is meconium formed?
hypoxia –> (+)AVP –> (+) colon smooth muscle to contact –> defecation
functional immature kidneys
Metanephros
anuria of fetus causes
oligohydramnios
respiration detected @
11 WEEKS
stages of lung development
- pesudoglandular (5-17 week)
- Cannalicular (16-25 weeks)
- Terminal sac (34th week)