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Animal Gestation. Review these Terms: Embryo Fetus Gestation Parturition Open Bred Settled Springer. We will define these together: Placenta Amniotic Sac Amniotic fluid Chorion Amnion Umbilical Cord Cotyledon Caruncle placentome. Gestation in Animals.
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Review these Terms: Embryo Fetus Gestation Parturition Open Bred Settled Springer We will define these together: Placenta Amniotic Sac Amniotic fluid Chorion Amnion Umbilical Cord Cotyledon Caruncle placentome Gestation in Animals
Gestation Periods in Animals • Mare – 336 • Cow – 283 • Ewe – 150 • Sow – 114 • Gyp - 63
The Placenta – a temporary organ present only in female placental mammals during gestation. • composed of two parts, one is part of the fetus, the other part of the mother. • implanted in the wall of the uterus, • receives nutrients and oxygen from the mother's blood and passes out waste. • filters out some substances which could harm the fetus. • produces progesterone, which is important in maintaining the pregnancy; estrogen, and other hormones • delivered after the fetus ,and is called the afterbirth. • Non-placental mammals • Monotremes and marsupials-egg-laying mammals found in Australia and New Guinea, • Birds are non placental
The three potential maternal layers in a placenta are: • Endothelium lining endometrial blood vessels. • Connective tissue of the endometrium. • Endometrial epithelial cells. http://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/placenta/structure.html
Amniotic sac • Tough, thin, transparent pair of membranes, which hold a developing fetus. • The inner membrane, the amnion, contains the amniotic fluid and the fetus. • The outer membrane, the chorion, contains the amnion and is attached to the placenta.
The Umbilical Cord • Attaches the placenta to the fetus • The site of the former umbilical cord attachment is the umbilicus, or navel.
Placental Classifications • Classification is based on: • 1. Shape • 2. The number of layers of tissue between maternal and fetal vascular systems. http://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/placenta/plac_types.jpg
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/placenta/structure.htmlhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/placenta/structure.html
Diffuse Placenta – Equine and Porcine • Attached smoothly to entire uterus Equine Placenta with fetus
Multiple areas of attachment called cotyledons. Cotyledons - fetal portions of this type of placenta Caruncles - maternal contact sites Placentome - cotyledon-caruncle complex Cotyledonary Placenta - Ruminants
Caruncles • In membranes Cross-section
Cotyledon: the fetal side of the placenta • Caruncle: the maternal side of the placenta • Placentome: a cotyledon and caruncle together
Zonary Placenta – Dogs, Cats… • Placenta is attached in band-like zones in the uterus.
This image shows the end of one uterine horn of the cat. The zonary placenta of two fetuses are clearly visible through the uterine wall.
Primates Rodents Discoid Placental Attachment
Review – Quiz • Name an animal with each type of placenta: • 1. Cotelydonary • 2. Discoid • 3. Zonal • 4. Diffuse • Bonus – what type of placenta do humans have.
21/2-3IN CLAW BUDS and SCROTUM RECOGNIZABLE PALATE and STERNUM CLOSED PLACENTA ATTACHED COTYLEDONS PRESENT. Cattle - 60 DAYS
5-7 INCHES RAT SIZE FINE HAIR ON EYEBROWS CLAWS DEVELOPED Cotyledons PRESENT ON AMNION HORN PITS PRESENT Cattle 90 days
5-7in small cat size find hair on eyebrow claws develop 120 days
18-23cm 7-9in large cat size hair on eyebrow and lips 40-60 cm (15-24 in ) hair on inside of the ear, around the horn pits tip of tail, & muzzle. 150 days 180 days
22-30 in long hair on tip of tail Hair on the metatarsal, metacarpal and phalangeal region 24-34 in Fine short hair all over the body Incisor teeth not erupted 210 days 240 days
70-100 cm (28-40 in ) Hair coat complete incisor teeth erupted 270 days
Relaxin: protein hormone that acts with progesterone to maintain pregnancy and to promote loosening of pelvic ligaments at the time of parturition.
First sign of the calf should be two front legs facing downward.