Post on 13-Dec-2015
Animal Gestation
Gestation-Unit 6 Frameworks Objectives
6.1 Define Terms
6.3 Describe female reproductive systems
6.3 Label reproductive parts
Comparative analysis of sheep and pig uterus
Gestation in Animals
Review these Terms: Embryo Fetus Gestation Parturition Open Bred Settled
We will define these together: Placenta Amniotic Sac Amniotic fluid Chorion Amnion Umbilical Cord Cotyledon Caruncle placentome
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
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
Type of Placenta Common Examples
Diffuse Horses and pigs
CotyledonaryRuminants (cattle, sheep,
goats, deer)
Zonary Carnivores (dog, cat, ferret)
DiscoidHumans, apes, monkeys and
rodents
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/placenta/structure.html
Diffuse Placenta – Equine and Porcine
Attached smoothly to entire uterus
Equine Placenta with fetus
Cotyledonary Placenta - Ruminants Multiple areas of attachment
called cotyledons.
Cotyledons - fetal portions of this type of placenta
Caruncles - maternal contact sites
Placentome - cotyledon-caruncle complex
Cotoledenary Placenta – Uterus Partially Removed
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.
Uterus Removed
Chorioallantois Removed
Placenta Opened, showing vascular structure
Discoid Placental Attachment
Primates Rodents
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.
Fetal Development
Cattle - 60 DAYS
21/2-3IN CLAW BUDS and SCROTUM
RECOGNIZABLE PALATE and STERNUM
CLOSED
PLACENTA ATTACHED
COTYLEDONS PRESENT.
Cattle 90 days
5-7 INCHES RAT SIZE FINE HAIR ON
EYEBROWS CLAWS DEVELOPED Cotyledons PRESENT
ON AMNION HORN PITS PRESENT
• 5-7in small cat size find hair on eyebrow claws develop
150 days 180 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.
210 days 240 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
70-100 cm (28-40 in ) Hair coat complete incisor teeth erupted
Cattle Gestation – 283 days
28 day pig embryos
28 day pig embryos
60 day old pig embryo
Relaxin: protein hormone that acts with progesterone to maintain pregnancy and to promote loosening of pelvic ligaments at the time of parturition.
One of the first signs of birth is the water bag.
First sign of the calf should be two front legs facing downward.
Parturition!