Comparative Implantation and Placentation Flashcards
-process in which a developing embryo,
moving as a blastocyst through a uterus,
makes contact with the uterine wall and
remains attached to it until birth.
IMPLANTATION
STAGES OF IMPLANTATION
a. Hatching
b. Apposition
c. Adhesion
d.Invasion
- the blastocyst sheds its zona pellucida.
- aid of endometrial secretions
Hatching
blastocyst contacts the implantation site of the endometrium.
Apposition
trophoblast cells of the blastocyst attach to the receptive endometrial epithelium.
Adhesion
- invasive trophoblast cells cross the
endometrial epithelial basement
membrane and invade the endometrial stroma - humans and guinea pigs
Invasion
3 well-developed, mummified, and mineralized fetuses loosely attached to the omentum.
ABDOMINAL PREGNANCY
Membranous structure formed by apposition of the fetal chorioallantoic membrane and the maternal endometrium (decidua).
PLACENTA
*Parts of the Placenta
Fetal part= ______
- connects with the embryo through the umbilical cord.
chorion
*Parts of the Placenta
Maternal part= __________
- endometrium of maternal uterus
endometrium
Basic types of placenta
Choriovitelline/yolk sac placenta
Chorioallantoic placenta
when the fused vascular choriovitelline membranes become attached to the endometrium common in marsupials.
Choriovitelline/yolk sac placenta
chorioallantoic membrane becomes attached to the endometrium. definitive form of placentation in higher mammals.
it may be preceded by and co‐exist with a temporary choriovitelline placenta.
Chorioallantoic placenta
CLASSIFICATIONOF CHORIOALLANTOIC PLACENTATION
Diffuse
Cotyledonary
Zonary- complete/incomplete
Discoidal- single or double
Villi are distributed throughout the chorionic vesicle except the undilated ends.
Horse and pigs
Equine placenta- microcotyledonary (diffuse distribution of microplacentomes).
DIFFUSE PLACENTA
Villi form tiny oval or round areas called cotyledons all over the external surface of the chorionic vesicle, except the undilated ends.
Cotyledons attach to specific areas, caruncles, in the lining of the uterus.
A cotyledon and caruncle attached to it combine to form the placentome.
COTYLEDONARY PLACENTA
discrete area of interdigitation between a maternal caruncle and a
fetal cotyledon.
Placentome-