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Ch14 Placentation, Gestation and parturition - Coggle Diagram
Ch14 Placentation, Gestation and parturition
Final prepartum steps of Repro
Formation of placenta
placenta is an organ of metabolic interchange between the conceptus and the dam (endocrine organ)
classified by the distribution of chorionic villi
Zonary
band-like zone of chorionic villi (dogs and cats)
Discoid
Form a regionalized disc (rodents and primates)
Diffuse
Have uniform distribution of villi that cover the surface of the chorion (pig)
Cotyledonary
Numerous, discrete button-like structures call cotyledons (ruminants)
Classification via microscope
Endotheliochorial - 5 layers
Epitheliochorial - 6 layers
Hemochorial - 3 layers
placenta secretes hormones
Stimulate ovarian function
Stimulate mammary function
influence fetal growth
Maintain pregnancy
Assist in parturition
Progesterone and estrogens
Acquisition of endocrine function of the placenta
this is important for the maintenance of pregnancy and the induction of parturition
Initiation of parturition
Giving birth to young - Immediately preceded lactation, uterine repair and return to cyclicity
Initiated by fetus, complex cascade of endocrine events:
promote myometrial contractions
Dilation of cervix
expulsion of the fetus
expulsion of the extraembryonic membranes
Gestation - the act of carrying or being carried
Three stages of parturition
Stage 2: Expulsion of the fetus
Requires strong myometrial and abdominal muscle contractions
Stage 3: Expulsion of the fetal membranes
Requires myometrial contractions
Stage 1: initiation of myometrial contractions (removal of progesterone block)
Fetus initiates this stage