Types Of Placenta Flashcards
Types of placenta Based on degree of intimacy:
- Non deciduous placenta
- Deciduous Placenta
- Contra deciduous placenta
Types of placenta Based on types of implantation:
- Superficial Placenta
- Eccentric Placenta
- Interstitial Placenta
Types of placenta Based on distribution of chorionic villi:
- Diffused Placenta
- Cotyledonary Placenta
- Zonary Placenta
- Discoidal Placenta
- Meta discoidal placenta
Types of placenta Based on degree of involvement of foetal
and maternal tissues:
- Epitheliochorial Placenta
- Syndesmochorial Placenta
- Endotheliochorial Placenta
- Haemochorial Placenta
- Haemoendothelial Placenta
● Superficial implantation
● The blastocyst lies in the uterine cavity.
● During the attachment with the uterine wall, the blastocyst surface generates finger like projections called chorionic villi, that, penetrate into the uterine wall,and are loosely united.
● The chorionic villi are simply
withdrawn from the uterine wall.
Non deciduous placenta or Semi placenta
● ‘Decidua’ means ‘to shed’
● Implantation is more intimate.
● The chorionic villi are complicated, branched and intimately connected with the endometrium.
● At birth, uterine tissue is also pulled out with the shedding of blood.
Deciduous placenta or Placenta Vera
● The implantation is intimate but both maternal tissue as well as foetal portion of placenta get torn off and are absorbed by mother’s leucocytes.
● Found in Perameles and T alpa (mole).
Contra deciduous placenta
● Embryo is superficially attached with the uterine wall.
● The embryo remains within the lumen of the uterus.
Superficial or Central placenta
● Embryo lies within the uterine epithelial fold.
● Later, the epithelial fold encloses the embryo almost completely.
Eccentric placenta
● Embryo burrows into the uterine mucosa below the epithelium and becomes surrounded completely by the endometrial tissue of the uterus.
Interstitial placenta
● Chorionic villi are numerous and are uniformly scattered over the chorion.
Diffused placenta
● Chorionic villi are aggregated in
certain regions to form small tufts.
● The remaining part of the chorion smooth. surface remains
Cotyledonary placenta
● Chorionic villi are developed in form of a belt or a band around the middle of the embryo.
Zonary placenta
● Chorionic villi are arranged in a circular plate on the dorsal surface of embryo.
Discoidal placenta
● Chorionic villi are at first scattered all over the chorion but later becomes restricted to one or two discs.
Metadiscoidal placenta