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level: Porcine

Questions and Answers List

level questions: Porcine

Question	Answer
The gestation period of the sow?	111-121 days 15½ weeks 3 months, 3 weeks and 3 days) with extreme variations of 105-126 days
A secondary ovocyte is ovulated. Fertilization takes place in the ____ ____ and occurs within ___ hours of mating. Up to ___ % of zygotes do not undergo any further development.	uterine tube 2 45
Although more ova usually ovulate from the (1) ovary than from the (2), the embryos migrate and end up being evenly spaced in both uterine horns. Early death of some embryos occurs between days (3). A minimum of (4) viable embryos are necessary (prior to implantation) for the pregnancy to continue. If there are less than (4), the embryos are re-absorbed following luteolysis of the corpora lutea. The luteolytic effect of a comparatively empty uterus (i.e. less than four viable embryos) is greatest between days (5), but greatly reduced after day (6).	1. left 2. right 3. 6 and 9 4. four 5. 7 and 10 6. 12
Embryonal migration and spacing starts on day ___ and is completed by day ___. On day ___, the blastocyst begins to elongate bilaterally and can reach a length of 1,5 m by day ___; at this stage it is only 2-5 mm wide. The elongated lateral extensions of the blastocyst later become folded in a concertina-like fashion, with the embryonal disc situated in its middle.	8-10 15 11 17
Chorionic attachment to the endometrium starts on about day ___, and is completed by about day ___.	20 24
The yolk sac is initially ____ and ____; it is orientated cranio-caudally and extends the length of the developing embryo. However, after the cranial and caudal ends regress, only the ____ part remains dilated.	narrow and elongated central
The remaining yolk sac regresses as the ____ expands, and the role of the ____ circulation is soon superseded by the ____ circulation. The yolk sac is reduced to a diameter of 1 cm by day ____ and has completely disappeared at partus. The vitelline duct closes on about day ____.	allantois vitelline umbilical 58 70
The chorioamniotic folds are visible by day ___, and the amnion and chorion are completely formed by day ___.	15 18
Describe the amniotic fluid.	The amniotic fluid is watery and slightly opaque; no amniotic plaques are formed.
The amnion occupies the ____ part of the central portion of the chorionic sac, while the ____ occupies the rest of the sac (see Fig. 32). As the allantois does not extend dorsally between the amnion and chorion, an ____ is formed in this region. The ____ surface of the amnion and the ____ surface of the central portion of the allantois fuse to form an allantoamnion. The amniochorion and allantoamnion are both vascularized by the ____ circulation; the former forms part of the Pars fetalis of the placenta.	dorsal allantois amniochorion ventral dorsal umbilical
The allantois evaginates from the ____ on day ____. It soon develops two laterally directed extremities, which project into the elongated portions of the chorionic sac. Allantoic extremities reach the lateral tips of the chorionic sac by day ____.	metenteron 14-15 17
By day ____, the allantois has filled the exocoelom; however, it does not expand between the amnion and chorion. From day ___, the allantois begins to fuse with the chorion to form the allantochorion. The chorionic sac is largely vascularized by day ____, but the tips of the sac later lose their vascularization and become necrotic.	24-25 19 24-25
The ____ surface of the central portion of the allantois fuses to the _____ surface of the amnion to form an allantoamnion. The rest of the allantois fuses with the ____ (except the necrotic tips) to form _____. The allantoamnion and allantochorion are both vascularized by the _____ circulation; the latter forms part of the Pars fetalis of the placenta. Hippomanes are occasionally found in the allantoic fluid.	dorsal allantois ventral chorion chorion
The chorion fuses to the dorsal part of the ____ and to the entire allantois, except where the later forms the ____. The Pars fetalis of the placenta is thus formed by both ____ and ____.	amniotic sac allantoamnion amniochorion allantochorion
Endometrial attachment starts from about day __, which is when the chorionic villi begin to form. Villi occur over the entire chorionic sac, except at the necrotic end tips (the necrotic tips in the pig are far more prominent than those seen in the ruminants).	20
At this stage, the lateral extremities of the elongated chorionic sac are folded in a concertina-like fashion. However, the expansion of the _____ causes dilation and shortening of the chorionic sac and these folds are obliterated.	allantois
From about day 21, the chorionic sac develops numerous transverse ridges, which fit into corresponding furrows in the endometrium. The ridges are concentrated over the ____ region of the chorionic sac (so-called ____ zone); there are fewer and less well-developed ridges in the ____ zones and none on the necrotic tips.	central placental paraplacental
The chorionic ridges may develop secondary ridges (which interdigitate with secondary uterine furrows) and all bear stout chorionic villi (which interdigitate with uterine villi). Villi also occur between chorionic ridges and where there are no chorionic ridges (necrotic tips excluded). The epithelium covering the tips of the ridges and villi is ____, while that covering their bases is ____ (see Fig. 33).	cuboidal columnar
Both cell types have microvilli which interdigitate with the microvilli of the uterine epithelium (the pig thus differs from the ruminants where the microvilli on the tips of the ____ villi do not interdigitate).	caruncular
The inter-digitating ridges and villi are responsible for _____ nutrition. Metabolites requiring active transport are dealt with by the ____ epithelium, while those capable of diffusing (e.g. gases) utilize the ____ epithelium. The tips of the chorionic ridges and villi have intraepithelial capillaries.	hemotrophic columnar cuboidal
From about day __1__, histotrophe accumulates opposite the openings of the uterine glands. These accumulations, known as __2__, are visible as small, white, round vesicles that cause shallow, focal invaginations of the chorion (see Fig. 34). From the __2__, histotrophe spreads radially between chorionic and uterine epithelium and is taken up by the chorionic epithelium. Chorionic villi also grow into the __2__ to facilitate the absorption of histotrophe. The __2__ increase in number as the gestation progresses.	30 areolae
From about day 40, the chorionic sac can be divided into five zones:  A __1__ zone occupying the central half to two thirds of the chorion. This zone is characterized by a rich capillary network and many folds, villi and areolae.  Two narrower __2__ zones lying on either side of the __1__ zone. These areas have fewer folds, villi and areolae, and the blood vessels arranged more longitudinally.  Two ____ ____ lying peripheral to the __2__ zones; here there are no folds, villi, areolae or blood vessels.	1. placental 2. paraplacental 3. necrotic tips
By the end of the first third of gestation, adjacent chorionic sacs lie with their necrotic tips close together. With continued expansion, the sacs invaginate each other until the ____ zones make contact (by the end of the second third of gestation) and, eventually, the borders of the placental areas lie in apposition. Neighbouring sacs then fuse to each other, usually without vascular anastomoses developing between the placentae (fusion of adjacent allantoic circulations with the development of freemartins is extremely rare).	paraplacenta
At partus, the ____ forming part of the placental zone remains attached to the endometrium. Each fetus must therefore rupture its amnion sac and the fused para-placental zone of the chorion. Thereafter it passes down the long fused ____ sac. Alternatively, the fused paraplacental zones can rupture spontaneously a few days prepartus.	amniochorion chorionic
The umbilical cord is covered by simple squamous amniotic epithelium. It contains the ______1_____, __2__, _____3_____ and __4__. The two arteries are spirally twisted around each other. The right __5__ later completely disappears. The __4__ remains open until just before birth but the __2__ closes at about day 70. The umbilical cord can be as long as _6_ cm and is, relatively, the longest of all domestic mammals.	1. Aa. and Vv. umbilicales 2. vitelline duct 3. Aa. and Vv. vitellinae 4. allantoic duct 5. V. umbilicalis 6. 25
Classify theporcine placenta..	1. chorioamniotic 2. chorioallantoic 3. adeciduate 4. incompletely diffuse 5. epitheliochorial