histology of Embryology placenta

histology of Embryology placenta

1. DR SAIMA ASHRSF

PLACENTA

2. PLACENTA
•The placenta is an Organ that connects the
developing Fetus to the uterine wall to allow
nutrient uptake, waste elimination, and gas
exchange via the mother's blood supply

•Villi

•Primary

•Secondary

•Tertiary

6. COMPONENT OF THE PLACENTA
•Fetal component is trophoblast and extra
embryonic mesoderm

•Maternal component is endometrium

10. COMPONENTS OF THE PLACENTA
Decidua

D. Basalis D. Capsularis


Chorion

Chorion frondosum chorion leave

11. PLACENTA OF VARIOUS TYPES
•The placentas of all eutherian (placental) mammals
provide common structural and functional features,
but there are striking differences among species in
gross and microscopic structure of the placenta.

12. •The types of fetal membranes participating in
exchange
•The gross shape of the placenta(chorion
frondosum) and the distribution of contact sites
between fetal membranes and endometrium.

•The number of layers of tissue between maternal
and fetal vascular systems.

•Differences in these properties allow classification of
placentas into several fundamental types.

13. •Examination of placenta from different species
reveals striking differences in their shape and the
area of contact between fetal and maternal tissue
Classification Based on Placental Shape and
Contact Points

14. Almost the entire surface of the allantochorion is
involved in formation of the placenta. Seen
in horses and pigs.


Diffuse:

15. •Multiple, discrete areas of attachment called
cotyledons are formed by interaction of patches of
allantochorion with endometrium. The fetal portions
of this type of placenta are called cotyledons, the
maternal contact sites (caruncles), and the
cotyledon-caruncle complex a placentome. This
type of placentation is observed in ruminants

Cotyledonary:

16. COTYLEDONARY PLACENTA

17. •The placenta takes the form of a complete or
incomplete band of tissue surrounding the fetus.
Seen in carnivores like dogs and cats, seals, bears,
and elephants.

Zonary:

19. •Discoid: A single placenta is formed and is discoid in
shape. Seen in primates androdents.

20. CLASSIFICATION OF THE PLACENTA
BASED ON PARTICIPATION OF
MATERNAL AND FETAL TISSUE
•prior to formation of the mature placenta, there are
a total of six layers of tissue separating maternal and
fetal blood.

21. •There are three layers of fetal extraembryonic
membranes in the chorioallantoic placenta of all
mammals, all of which are components of the
mature placenta

•Endothelium lining allantoic capillaries

•Connective tissue in the form of chorioallantoic
mesoderm

•Chorionic epithelium, the outermost layer of fetal
membranes derived from trophoblast

22. •There are also three layers on the maternal
side, but the number of these layers which
are retained - that is, not destroyed in the
process of placentation - varies greatly
among species. The three potential
maternal layers in a placenta are:
•Endothelium lining endometrial blood vessels

•Connective tissue of the endometrium

•Endometrial epithelial cells

23. MATERNAL AND FETAL LAYERS OF
PLACENTA

25. Components
of the
placenta
from
Maternal
side
Endometrial
Epithelium
Connective
Tissue
Uterine
Endothelium
Epitheliochorial

•+
•+
• +
Endotheliochorial

•+
•-
(connective
tissue is
absent)
•-(uterine
epithelium
absent) Hemochorial

•-(all
maternal
layers are
absent)
•-
•-
Types of placenta

26. SUMMARY OF SPECIES DIFFERENCES
IN PLACENTAL ARCHITECTURE

Types of placenta

•Diffuse,epitheliochorial
Horses and pigs

•Cotyledonary, epitheliochorial
Ruminants (cattle, sheep, goats, deer)

•Zonary, endotheliochorial
Carnivores (dog, cat, ferret)Discoid,
hemochorial

27. TYPE OF ANCHORING AND FATE AT
BIRT
•Deciduate
•Non-Deciduate

The uterine lining may be shed with the fetal
membranes as “afterbirth” (a condition called
deciduate) or may be resorbed by the female
(nondeciduate).