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Gestation and Parturition - Coggle Diagram
Gestation and Parturition
Gestation
Final preparation steps of reproduction
aquistion of endocrine function of the placenta
initiation of parturition
formation of a placenta
Placenta
Placentas are classified according to the distribution of chorionic villi. These classifications are:
Zonary
have a band like zone of chorionic villi. Example = dogs and cats
discoid
form a regionalized disc Example = rodents and primates
Diffuse
Diffuse placentas have uniform distribution of chorionic villi that cover the surface of the chorion. Example = pig
cotyledonary
have numerous, discrete button- like structures called condyles Example = ruminants
Prefix = maternal side "epithelio" , Suffix = fetal side "Chorial", epitheliochorial
epitheliochorial= 6 layers, sow and mare
Endothelialchorial = 5 layers, dogs and cats
hemochorial = 3 layers, primates and rodents
Placenta endocrine function
The placenta secretes hormones that can:
influence fetal growth
stimulate mammary function
placental lactogen (also called somatomammotropin)
maintain pregnancy
assist in parturition
stimulate ovarian function
eCG in the mare
The placenta secretes progesterone and estrogens
Parturition
three stages of parturition
Stage 2: expultion of the fetus
Expulsion of the fetus requires strong myometrial and abdominal muscle contractions
Stage 3: expulsion of fetal membranes
expulsion of fetal membranes requires myometrial contractions
Stage 1: initiation of myometrial contractions (removal of progesterone block)
The fetus initiates stage 1 of parturition
