Changes

In sheep, there are between 90 and 100 cotyledons distributed across the surface, and in cattle 70-120 have been observed.

In sheep, there are between 90 and 100 cotyledons distributed across the surface, and in cattle 70-120 have been observed.

The '''placentome''' consists of: a '''foetal cotyledon''' contributed by the chorion and a '''maternal caruncle''' originating from the endometrium.

The '''placentome''' consists of a '''foetal cotyledon''' contributed by the chorion and a '''maternal caruncle''' originating from the endometrium. These placentomes start forming about day 16 in the sheep and day 25 in the cow. In the sheep the placentomes form a '''concave''' structure, while in the cow they are '''convex'''. During gestation, these placentomes will greatly increase in diameter, nearing 5-6cm in the cow by the end of pregnancy.

 

These placentomes start forming about day 16 in the sheep and day 25 in the cow.

 

In the sheep the placentomes form a '''concave''' structure, while in the cow they are '''convex'''.

 

During gestation, these placentomes will greatly increase in diameter, nearing 5-6cm in the cow by the end of pregnancy.

==Dog and cat placenta==

==Dog and cat placenta==

The placenta contains unique transitory structures called '''endometrial cups'''.  

The placenta contains unique transitory structures called '''endometrial cups'''.  

They range from a few milimetres to several centimetres in diameter. There are usually between 5 and 10 endometrial cups distributed over the surface of the placenta. They are of both trophoblastic and endometrial origin.

They range from a few milimetres to several centimetres in diameter. There are usually between 5 and 10 endometrial cups distributed over the surface of the placenta. They are of both trophoblastic and endometrial origin. These structures produce '''equine chorionic gonadotrophi'''n (eCG) and develop between days 36 and 60 of pregnancy. From day 60 they begin to be sloughed and are no longer functional. The debris from the sloughing of the cup may form allantochorionic pouches, up to 2cm in length, which can be present in the placenta at term.

 

These structures produce '''equine chorionic gonadotrophi'''n (eCG) and develop between days 36 and 60 of pregnancy.

 

From day 60 they begin to be sloughed and are no longer functional. The debris from the sloughing of the cup may form allantochorionic pouches, up to 2cm in length, which can be present in the placenta at term.

 

The '''hippomane''' is another normal structure of pregnancy: it is liver-like in texture and thought to arise as an out-pouching of the allantois which eventually forms a pedicle and separates to float free in the allantoic cavity. Other suggestions include that it is a collection of debris, thought to be deposits from the foetal urine and cells.

The '''hippomane''' is another normal structure of pregnancy: it is liver-like in texture and thought to arise as an out-pouching of the allantois which eventually forms a pedicle and separates to float free in the allantoic cavity. Other suggestions include that it is a collection of debris, thought to be deposits from the foetal urine and cells.

Senger, P. (2003) '''Pathways to Pregnancy and Parturition''' ''Current Conceptions Inc''

Senger, P. (2003) '''Pathways to Pregnancy and Parturition''' ''Current Conceptions Inc''

[[Category:Pregnancy and Parturition]]

[[Category:Pregnancy and Parturition]]