PLACENTA -
A common tissue of foetus & mother (uterus) which is physical, physiological & endocrinal connection is known as placenta.
FUNCTION -
To provide nutrients to foetus. To remove metabolic waste. Helpful in respiration. Store food in the form of glycogen.
It produces estrogen, prgesteron & relaxin.
Note :- A placenta consists of 6 tissues. Three from the foetal walls & 3 from mother's uterus.
The foetal tissues are -
1. Foetal endometrium i.e. blood capillaries.
2. Connective tissue.
3. Chorionic epithelium
The maternal tissue are -
1. Mucous epithelium of uterine walls
2. Connective tissue
3. Maternal endothelial
According to the presence or absence of any of these tissues the placenta may be of many types.
In man placenta is of following types - 1. Haemochorial 2. Discoidal 3. Decidute
1. HAEMOCHORIAL - All maternal tissues are eraded so that chorionic epithelium is bathed directly in the maternal blood (present in irregular spaces or sinuses).
2. DISCOIDAL - Where villi develop only on one side so that it looks like a disc.
3. DECIDUATE - Close relation between trophoblastic villi & uterine wall. At the time of birth considerable bleeding & tearing of tissues.