Download mesoderm

组织胚胎学课件
中国医科大学
基础医学院
组胚—英文教学组
HUMAN
EMBRYOLOGY
Department of Histology and Embryology
China Medical University
Chapter 4
Further Development of Embryo
Formation and
differentiation of
trilaminar germ disc
1. formation of epiblast and hypoblast :
By the 8th day, the inner cell mass
differentiates into two layers of cells
epiblast (columnar)
bilaminar germ disc
hypoblast (cuboidal)
Amnionic
cavity
epiblast
hypoblast
Bilaminar
germ disc
---epiblast: primary ectoderm
amniotic cavity: amniotic fluid
roof: amniogenic cells
floor: epiblast
--- hypoblast: primary endoderm
hypoblast
→Heuser’s
→primary yolk sac
membrane
Amnionic cavity
epiblast Bilaminar
hypoblast
germ disc
Extra-embryonic
mesoderm
Primary yolk sac
secondary yolk sac
Body stalk
Extra-embryonic
cavity
Extra-embryonic
mesoderm
Primary yolk sac
extra-embryonic mesoderm →
extra-embryonic cavity (chorionic cavity)
--visceral layer
--parietal layer
/secondary yolk sac: yolk sac
---body stalk (connecting stalk): formed
by extra-embryonic mesoderm
2. formation of mesoderm:
in the early of the 3rd week
---primitive streak: cells of epiblast
proliferate to form a longitudinal arranged
cell cord
* determination of head and tail of germ disc
2. formation of mesoderm: in the
early of the 3rd week
---primitive streak
---primitive node (primitive knot)
2. formation of mesoderm: in the
early of the 3rd week
---primitive streak:
---primitive node (primitive knot)
---primitive pit (blastopore)
---mesoderm: intra-embryonic mesoderm
---endoderm: hypoblast cells are replaced by
epiblast cells
---ectoderm: epiblast changed the name into
ectoderm
by the end of the 3rd week
trilaminar germ disc:
endoderm + mesoderm + ectoderm
---head process→notochordal tube → notochord
---buccopharyngeal membrane
---cloacal membrane
notochord
3.differentiation of trilaminar germ disc
4th –8th weeks
---differentiation: same cells which are
primordial and inmuture differentiate into
different cells which have specific structure
and function
---induction: some tissues effect the
differentiation,
and
determine
the
differentiating orientation of another tissue
(1) differentiation of ectoderm:
from 18th –19th days
---neural plate: neuro-epithelium (neural
ectoderm): pseudostratified columnar epi.
neural plate
Notochord
(1) differentiation of ectoderm:
from 18th –19th days
---neural plate
Neural groove
---neural groove
---neural fold
Notochord
---neural tube: →CNS
/anterior neuropore: closed by 25th days
/posterior neuropore: closed by 27th days
Neural tube
Anterior and posterior
neuropores
Spina bifida
anencephaly
---neural tube: CNS
---neural crest: two lines of cell cords→ganglions
(2)differentiation of mesoderm: 17th day
paraxial
Mesoderm
endoderm
Neural groove
Intermediate
mesoderm
Lateral
mesoderm
---paraxial mesoderm
somite: 20th days, 3 pairs/per day, 42-44
pairs by the end of 5th weeks
-sclerotome: →bone, cartilage
-dermatome: → dermis and hypodermis
-myotome: →skeletal muscle
Neural canal
Somite
Intermediate
mesoderm
endoderm
Intraembryonic
cavity
---intermediate mesoderm:
→kidney and reproductive system
---lateral mesoderm:
Intra-embryonic coelom: →body cavity
parietal or somatic mesoderm: →muscle, CT, parietal
layer of pleura, peritoneum and pericardium
visceral or splanchnic mesoderm: →muscle, CT of
digestive tract, visceral layer of pleura, peritoneum
and pericardium
Parietal
mesoderm
Intra-embryonic
cavity
visceral
mesoderm
3. differentiation of endoderm:
primitive gut: →digestive,
respiratory and urinary system
foregut
midgut
oropharyngeal
membrane
hindgut
Cloacal
membrane
1. Embryonic period is B
A. from fertilization to the end of week 2
B. from fertilization to the end of week 8
C. from week 3 to the end of week 8
D. from week 5 to the end of week 8
E. from week 9 until birth
2. How long will an individual stay in the uterus of its
mother? C
A. 18 weeks
B. 28 weeks
C. 38 weeks
D. 48 weeks
E. 58 weeks
3. What is penetrated by a spermatozoon during the
process of fertilization C
A. oogonium
B. primary oocyte
C. secondary oocyte
D. primary follicle
E. primordial follicle
4. Which protein is receptor of spermatozoa on the zona
pellucida? C
A. ZP1
B. ZP2
C. ZP3
D. ZP4
E. ZP5
5. The time of implantation is C
A. from 1st-2nd day to 7th-8th day
B. from 3rd-4th day to 9th-10th day
C. from 5th-6th day to 11th-12th day
D. from 7th-8th day to 13th-14th day
E. from 9th-10th day to 15th-16th day
6. Which structure is not belong to early blastocyst ? E
A. trophoblast
B. zona pellucida
C. inner cell mass
D. blastocoele
E. endoderm
7. Which is not correct about implantation D
A. blastocyst will be imbedded in the endomytrium
B. zona pellucida disappears
C. polar trophoblast secretes proteinase
D. endomytrium is in proliferative phase
E. there is a corpus luteum of pregnancy in the ovary
8. The most common position of implantation is E
A. mucus of uterine tube
B. mucus of ampullary portion of uterine tube
C. ovary
D. mucus of cervix of uteru
E. mucus of body of uterus
Chapter 4
Further Development of Embryo
Question
s
1. Describe the formation of bilaminar germ disc and its
associated structures.
2. Describe the formation of trilaminar germ disc and its
associated structures.
3. Describe the differentiation of three germ layers briefly.
4. Preview fetal membrane and placenta.