Stages of Fetal Development Flashcards
From ovulation to fertilization
Ovum
From fertilization to implantation
Zygote
From implantation to 5–8 weeks
Embryo
From 5–8 weeks until term
Fetus
Developing embryo and placental structures throughout pregnancy
Conceptus
The earliest age at which fetuses survive if they are born is generally accepted as 24 weeks or at the point a fetus weighs more than 500–600 g
Age of viability
3 STAGES OF FETAL DEVELOPMENT:
Pre-embryonic (Zygote)
Embryonic Stage
Fetal Stage
Stage of Fetal Development
First 2 wks. (14 DAYS), beginning with
fertilization
Pre-embryonic (Zygote)
union of the ovum and spermatozoon
Other terms: conception, impregnation, or fecundation
Fertilization
Fertilization
union of the ___ and ____.
Occurs in the ____ of the _____.
Functional life of spermatozoon – _____hrs.
ovum and spermatozoon
outer 3rd of the fallopian tube (ampulla)
48 – 72 hrs
Stage of Fetal Development
From day 15 – 8 wks. after conception, or until the embryo measures 3 cm from crown to rump
Embryonic Stage
Embryonic Stage
At the end of __ wk. all _____ and _____ are present, and the ____ is unmistakably human.
8th; organ systems and external structures; embryo
Embryonic Stage
From day __ – _ wks. after conception, or until the embryo measures _ cm from crown to rump
day 15 - 8 wks after conception; 3 cm
Stage of Fetal Development
From approximately 9 wks. – term
Fetal Stage
Fetal Stage
Fetus less vulnerable to _____ except for those affecting CNS functioning.
teratogens
Period of organogenesis.
1st trimester
Period of rapid increase in length.
2nd trimester
Period of continuous growth & development.
3rd trimester
Intrauterine Fetal Development:
1) ___ M sperms enter the upper part of vagina, only _ M enter the uterus up to ampulla
300 M enter the upper part of vagina; 3 M enter the uterus up to ampulla
Intrauterine Fetal Development:
2) Sperm penetrate the _____ by releasing an enzyme ______ (FERTILIZATION)
zona pellucida; hyaluronidase
Intrauterine Fetal Development:
3) Nuclei of ___ & ___ fuse, _______ combine
ovum & sperm; chromosomes
Intrauterine Fetal Development:
4) After the nuclei of ovum & sperm fuse, chromosomes combine, the ____ forms.
Zygote
Intrauterine Fetal Development:
5) ____ begins to form as zygote travels the uterine tube Into the uterus (Blastomeres)
Cleavage
Intrauterine Fetal Development:
6) _____ (16-CELL MASS) is produced within 3 days, Still surrounded by zona pellucida
Morula
Intrauterine Fetal Development:
7) Morula enters the __________.
uterine cavity
Intrauterine Fetal Development:
8) _____ forms at the center of morula, while ZONA PELLUCIDA remains the same size
Blastocele
Intrauterine Fetal Development:
9) _____ forms after blastocele.
BLASTOCYST
Intrauterine Fetal Development:
10) Blastocyst hatches from the ______ ( _ day after fertilization) as it enters the uterus
zona pellucida; 6th day
Intrauterine Fetal Development:
11) _____ occurs after blastocyst hatches from the zona pellucida ( _ to _ days after fertilization).
Implantation; 8-10 days
Intrauterine Fetal Development:
12) ____ cells secretes an enzyme ( _____ ) which erodes the epithelial uterine lining
Trophoblast; strypsin
Intrauterine Fetal Development:
13) Trophoblast cells engulf & destroy cells of the _____.
uterine lining
Intrauterine Fetal Development:
14) New _____ grow, foretelling the growth of the _____.
capillaries; placenta
Intrauterine Fetal Development:
15) After implantation, the endometrium is termed ____.
decidua
Intrauterine Fetal Development:
16) ____ (inner cell mass) forms 2-layered disc.
Embryoblast
Intrauterine Fetal Development:
17) ____ develops from trophoblast and contains _____ on its surface.
Chorion; chorionic villi
Intrauterine Fetal Development:
18) ____ burrow into the decidua basalis
Villi
Intrauterine Fetal Development:
19) As villi burrow into the decidua basalis, the formation of _____ starts to develop.
placenta
Intrauterine Fetal Development:
20) Chorion becomes the covering of the side ___ of the placenta (contains major umbilical blood vessels).
fetal
Intrauterine Fetal Development:
21) ____ develops from the inner cell mass of the blastocyst
Amnion
Intrauterine Fetal Development:
22) Developing ____ draws the amnion around itself to form a ______.
embryo; fluid-filled sac
Intrauterine Fetal Development:
23) Amniotic cavity derives its fluid by _____ from the ______.
diffusion; maternal blood
Intrauterine Fetal Development:
24) ____ is also formed.
Yolk sac
Intrauterine Fetal Development:
25) _____ & _____ are manufactured in the yolk sac (2nd - 3rd wk.)
Blood cells & plasma
Intrauterine Fetal Development:
26) ___ begins to beat & circulate blood through the embryo, connecting ____, ____ & ____ sac (end of 3rd wk.)
Primitive; stalk, chorion & yolk sac
Intrauterine Fetal Development:
27) Part of _____ incorporated into the embryo’s body as the primitive GIT (4th wk.)
yolk sac
Intrauterine Fetal Development:
28) Connecting stalk forms the _____ (5th wk.)
umbilical cord
Intrauterine Fetal Development
300 M sperms enter the _____, only 3 M enter the ___ up to _____.
upper part of vagina; uterus up to ampulla
BLASTOCYST
2 cell types are forming:
1) Embryoblast
2) Trophoblast