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41 Cards in this Set
- Front
- Back
mare gestation period |
336 days (11months +/- 11 days)
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cow gestation period |
285 days (9 months +/- 9 days)
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ewe gestation period |
150 days (5 months +/- 5 days)
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sow gestation period |
114 days (3 months and 3 weeks +/- 3 days)
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dog & cat gestation period |
63 days (2 months +/- 2 days)
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Fertilization
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It is the process, when sperm meets the ovum to make a zygote. fertilization takes place in the ampulla part of oviduct
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Transportation of ovum
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The fimbria of oviduct move and generate a current, so the ovum moves into the ostium (opening) of the oviduct.
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Capacitation
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capacitation refers to the membrane changes or "uncoating" of the sperm cell in female reproductive tract
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Implantation
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embedding the blastocyst into the uterine mucosa
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Functions of Placenta
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-gaseous exchange
-waste product removal from fetus -provide nutrition to the fetus -hormone production (estrogen, progesterone and gonadotrophins are produced by placenta) |
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Placental Membranes |
There are 4 plancental membranes: Chorion, Amnion, Allantois and Yolk sac
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Chorion
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outer most layer and is attached to the endometrium of uterus.
Function: Its main function is absorption of uterine secretions and site of attachment along with allantois to the endometrium. |
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Amnion
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the inner most layer, that envelops the fetus. It contains the amniotic fluid. It also contains fetal urine and other secretions.
Function: This fluid acts as a "shock absorber" to protect the fetus |
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Allantois
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It is double layered sac present between chorion and amnion
Functions: It attaches to the endometrium along with the chorion. It also provides the fetal blood vessels to placenta. |
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Yolk Sac
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Usually it is of no importance in mammals. It is attached to the fetal intestine.
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We classify the placenta into different types based on:
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1. Based on gross attachment of fetal placental membranes to uterus
2. Based on histological attachment between fetal membranes and uterine tissue |
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Cotyledonary Placenta:
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seen in ruminants like cows, sheep and goats. On this type of placenta, we see multiple area of attachments
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Diffuse Placenta:
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seen in horses and pigs. The entire surface of the outer placental membrance (chorion) is attached to the uterine mucosa.
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Zonary Placenta:
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found in dogs and cats. Here the chorion layer of placenta is in the form of a complete band like structure around the fetus.
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Discoidal Placenta:
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seen in primates and humans. Here the plancental membranes are attached to the uterus with a disc like structure.
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Epitheliochorial Placenta
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The chorion of the fetal placenta is attached to the endometrium (epithelium) of uterus. This type of placentation is seen in cows, sheeps, goats, horses and pigs
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Endotheliochorial Placenta:
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The chorion of fetal placenta dips a little deeper into uterine tissue and come in contact with the endothelium of blood vessels. Examples: dogs and cats
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Hemochorial Placenta:
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Here the chorionic villi comes in direct contact with the blood in uterus. E.g Human placenta
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IN COWS
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-You can feel the corpus luteum on the ovary, if animal is 30-45 days pregnant.
-At 3 -months of pregnancy, the fetal membranes can be felt in uterus and also you can feel fremitus (vibration of blood in uterine artery). -At 4-months, fetus and caruncles are palpable -At 5-months, it is difficult to palpate the uterus per-rectal, as it drops over the brim of pelvis into abdomen. -At 8-9 months, fetus again can be felt through rectum. |
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IN HORSES
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-changes in tone of uterus: increased uterine tone by 18-22 days after breeding. Uterus becomes more tubular and turgid.
-embryonic vesicles can be felt as a bulge on bottom side of uterus during 30-90 days. The swelling is about the size of golf ball (3-4 cm. in diameter) -at about 30 days and it becomes about size of tennis ball -by 60 days and appears like a fluid sac. -At about 60-90 days, it becomes about the size of elongated football. -After 100 days of pregnancy, fetus can not be palpated as uterus drops down into abdomen |
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IN DOGS
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can be palpated through abdominal wall at 3-4 weeks of pregnancy
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IN EWES
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The abdominal palpation helps diagnosing pregnancy in sheep in the last two months of pregnancy
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radiographs |
In dogs and cats, the radiographs can help diagnosing pregnancy only after about 42 days of pregnancy, when fetal skeleton starts developing
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Ultrasounds
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This method is being used to diagnose pregnancy in sheep, horses, dogs, cats and pigs as early as 30 days after breeding.
-In dogs and cats, embryonic vessels can be visualized in uterus as early as 17-20 days of pregnancy and fetal heartbeat can be visualized as early as 25 days of pregnancy. -In horses, ultrasound can be done as early as 15 days after breeding, to diagnose the pregnancy. Ultrasonography is also useful for distinguishing between abnormal uterine conditions and pregnancy. |
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Biochemical Tests
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During pregnancy, the placenta takes over the role of producing the hormones. These hormones can be measured in blood, milk or urine to diagnose the pregnancy
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IN COWS
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The progesterone hormone conc. is measured in milk after 22 days of estrus or insemination. The presence of high conc. of progesterone in milk indicates failure of cow to return to estrus.
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IN HORSES:
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The fetal placenta produces PMSG (Pregnant Mare Serum Gonadotrophin) or ECG (Equine Chorionic Gonadotrophin) hormone.
The concentration of this hormone in blood, is at its peak between 40-100 days of pregnancy. The test is based on immuno-assay technology. |
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1st Stage of parturition
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uterine contractions dilate the cervix. The duration of time period of 1st stage is different in various species:
In cows and sheep: 2-6 hours In sows and dogs: 2-12 hours In mares: 1-4 hours |
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2nd Stage
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Expulsion of fetus - Both water bags (allantois and amnion sacs) rupture leading to expulsion of fetus. The uterine and abdominal contractions help the fetus to come out of the birth canal.
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3rd stage |
Expulsion of placenta. The placenta comes out immediately after expulsion of fetus. The normal duration of expulsion of placenta:
In cows and sheep - 24 hours after the parturition In mares - with in 2 to 4 hours after parturition In dogs and pigs - Placenta comes out along with the fetus because placenta completely wraps the fetus. |
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Retention of placenta
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common problem in cows and mares. If placenta is not delivered within 24 hours after parturition in cows and within 4 hours after parturition in mare, it is considered as a case of retained placenta. In such cases we have to manually remove the placenta and place antibiotics in uterus to prevent infection.
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Involution of Uterus:
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The uterus returns to its non-pregnant normal size after parturition
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In Cows:
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Involution of uterus occurs within 35 days post-partum. Normally the estrus cycle starts 45-60 days post-partum.
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In mares |
Involution of uterus is rapid but not completed by the time of "foal heat", that occurs within 6-12 days post-partum. Foal heat is usually accompanied by ovulation.
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In Ewes and sows
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It takes 25-30 days for complete involution of uterus
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In dogs |
The placental sites require about 12 weeks (90 days) to involute and heal.
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