composition

Primary villous shaft is formed at 2 weeks

Secondary villous shaft formed at 3 weeks

Third-level villi are formed at 4 weeks

cytotrophoblast shell

intervillous space

Smooth chorion (including decidua)

dense chorion (decidua basalis → placenta)

amniotic epithelium

extraembryonic mesoderm

Thin, tough, translucent and avascular

form the original umbilical cord

produce amniotic fluid

endoderm

extraembryonic mesoderm

hematopoietic stem cells

primordial germ cells

The blind sac that extends laterally into the body pedicle from the tail of the yolk sac

Two allantoic arteries→umbilical artery 2

Two allantoic veins→umbilical vein 1

original umbilical cord

Bridge, exchange material with maternal blood in the intervillous space

40~60cm long

amniotic membrane

decidua basalis

syncytiotrophoblast

Cytotrophoblast and its basement membrane

intravillous connective tissue

Intravillous capillary endothelium and basement membrane

Amniotic cavity (between epiblast and trophoblast)

Yolk sac (extended proliferation of marginal hypoblast cells)

Attached to the outside of the yolk sac and amniotic sac

Attached to the inner surface of the trophoblast

The part of the extraembryonic mesoderm that connects the extraembryonic visceral wall mesoderm and the extraembryonic body wall mesoderm is getting narrower and narrower, and is called the body pedicle.

will develop into the main part of the umbilical cord

mesoderm

endoderm

ectoderm

Notochord degenerates into disc nucleus pulposus

Notochord, oropharyngeal membrane, cloacal membrane without intraembryonic mesoderm

The notochord is the primordium of the spine

The notochord induces the ectodermal cells above it to form the [neural plate] → the middle of the neural plate sinks to form the [neural groove] → the neural groove sinks, the neural plate changes to form the [neural fold] → the neural folds fuse, and the neural groove closes to form the [neural tube] → anterior The neuropore closes to form the brain, and the posterior neuropore closes to form the spinal cord.

Lateral border cells of the neural plate → neural crest → peripheral nervous system

Other surface ectoderm → epidermis and skin appendages

Mesoderm on both sides of the notochord - paraaxial mesoderm

Lateral somite mesoderm-intermediate mesoderm

Intermediate mesoderm lateral-lateral mesoderm

primitive digestive tube

Cephalic side>Caudal side→Cranial fold

Ectoderm>Endoderm→Tailfold

Middle>Edge→Side pleats

oviduct

Uterus

12 to 16 blastomeres

Trophoblast

inner cell mass

blastocyst cavity

Extreme trophoblast adheres to endometrial epithelium

proteolytic enzyme

Trophoblast

Increased secretion of uterine glands

increased blood supply

Thickness increases

stromal cells called decidual cells

decidua basalis

decidua

parietal decidua

uterine fundus, uterine body

Cervix - placenta previa - dystocia, heavy bleeding

Outside the uterus—ectopic pregnancy—heavy bleeding

testis

epididymis

There is glycoprotein attached to the sperm head, which can prevent the release of acrosome enzyme. There are enzymes in the female reproductive tract that can degrade this glycoprotein. Only when the sperm passes through the female reproductive tract can it finally gain the ability to fertilize. This process is called capacitation.

fallopian tube ampulla

Sperm releases acrosome enzymes that dissociate corona radiata follicle cells

Sperm binds to the sperm receptor ZP3 in the zona pellucida and releases acrosome enzyme to form a pore in the zona pellucida (acrosomal reaction-sperm releases acrosome enzyme to dissolve the corona radiata and zona pellucida)

Sperm and egg union

Sperm development is normal and the number is sufficient

Sperm must be capacitated

Egg development is normal, estrogen and progesterone are normal

Sperm and egg meet within a limited time

Unobstructed male and female reproductive tracts

Recovering diploid karyotype, inheritance and variation

determine gender

Fertilization marks the beginning of new life and initiates embryonic development