| The gestation period is ____ in the bitch and ____ in the queen. | ± 63 days (8½-9 weeks)
± 56-59 days (8 weeks) |
| A primary ovocyte is ovulated and fertilization occurs in the _____ part of the ____ ____. | proximal
uterine tube |
| Describe ovulation in the bitch. | In the bitch, ovulation occurs on the second or third day of estrus. Spontaneous.
Either one or both ovaries may ovulate; when both ovaries ovulate, there is no relationship between the numbers of ova released by each ovary. |
| Describe ovulation in the queen. | The queen, however, ovulates 26-30 hours after coitus; ovulation is thus said to be induced and not spontaneous as it is in the bitch.
Either one or both ovaries may ovulate; when both ovaries ovulate, there is no relationship between the numbers of ova released by each ovary. |
| For 2-3 days after arriving in the uterus, the blastocysts migrate extensively between and within the uterine horns. When implantation begins (day ___ in the dog, day ___ in the cat), the uterine horns usually contain equal numbers of evenly spaced blastocysts. | 14-17
13-14 |
| The implanting blastocyst lies with its ____ pole against the mesometrial wall; the ____ ____ lies towards the antimesometrial wall and parallel to the longitudinal axis of the uterine horn. Attachment is initiated by simple ____ villi that develop at the ____ pole. These villi project into the openings of the uterine glands and are responsible for anchoring the blastocyst and early histotrophic nutrition. At this stage, the embryo proper is also directly exposed to histotrophe, as the ____ has not yet formed. | vegetal
embryonal disc
trophoblastic
vegetal
amnion |
| At implantation, the ventral portion of the yolk sac lies directly against the ____; the expanding extra-embryonic mesoderm and associated vitelline circulation have not yet reached the ____ pole. The early placenta is thus a bilaminar vitelline placenta (see Fig. 35). Later, once the extra-embryonic mesoderm has grown between the ____ and ____, but before the region is vascularized, the bilaminar vitelline placenta is converted to a trilaminar vitelline placenta. | trophoblast
vegetal
yolk sac
trophoblast |
| By day ___, the now extensive vitelline circulation has vascularized the trilaminar vitelline placenta; additionally, the chorio-amniotic folds have fused and the trophoblast has become chorion. The placenta is now classified as a ____ placenta (see Fig. 36). | 21
choriovitelline |
| When the expanding exocoelom reaches the choriovitelline placenta on about day ___, most of the mesoderm between the yolk sac and chorion is also split into ____ and ____. This loosens the yolk sac from the chorion, except for its most ____ and most ____ points, which remain attached to the chorion for the duration of the pregnancy. The loosened yolk sac and chorion are then physically separated by the expanding ____, which pushes between them on about day ___. | 24
splanchnic
somatic layers
cranial
caudal
allantois
25 |
| The expansion of the allantois also causes a marked reduction in the size of the (1). Although the (2) closes early, the "detached" (1) does not degenerate and disappear; instead, it lies ventral to the embryo as a wrinkled, elongated, tubular sac containing a yellowish-brown fluid. The (1) remains very vascular (vitelline circulation) and continues to play a role in (3); it may also continue contributing to embryonal nutrition by absorbing nutrients from the (4) and transporting them to the embryo via the (5) arteries. | 1. yolk sac
2. VItelline duct
3. hematopoesis
4. exocoelom
5. vitelline |
| Following fusion of the chorioamniotic folds, the amnion has formed by day ___. As in all species, the amnion is initially tightly adherent to the embryo. The amniotic sac later enlarges to accommodate the increasing volume of amniotic fluid. At partus, the amniotic fluid volume amounts to ____ ml in the dog, but is considerably ____in the cat. No amniotic plaques are formed in either species. | 21
50-70 ml
less |
| The allantois evaginates on day (1) and is initially restricted to the central region of the ovoid chorionic sac. As it expands into the exocoelom, the allantois pushes (2), between the chorion and amnion, on the (3) side of the embryo (which lies parallel to the longitudinal axis of the chorionic sac). Once it has extended over the amniotic sac, it continues (4) on the (5) side and pushes between the chorion and detached yolk sac. Ventral to the yolk sac it meets that portion of the allantois, which expanded (4) on the (3) side (apparently, the left and right portions of the allantois do not fuse when they meet - see Figs. 36 and 37). The allantois later also grows into the cranial and caudal ends of the chorionic sac. | 1. 21
2. dorsally
3. right
4. ventrally
5. left |
| From about day (1), the mesoderm of the allantois starts fusing with that of the (2) and (3) to form (4) and (5). The (4) and (5) are vascularized by the (6) circulation; the (6) circulation supersedes the (7) circulation on about day 25. | 1. 22
2. chorion
3. amnion
4. allantochorion
5. allantoamnion
6. umbilical
7. vitelline |
| At partus, the allantoic fluid volume is ____ ml in the dog, but only about ____ ml in the cat; hippomanes do not occur in the carnivores. | 30-120
3 |
| Initially, simple ____ villi develop at the ____ pole of the blastocyst. These villi project into the uterine glands and are responsible for ____ the blastocyst and early ____ nutrition (day 17). Once the chorion and amnion have formed (day ___), the spherical chorionic sac gradually elongates until it forms a ____ with rounded ends (see Fig. 38). | trophoblastic
vegetal
anchoring
histotrophic
21
cylinder |
| Simple villi start forming over the central third of the chorionic sac such that they form a transverse belt incorporating the villi of the vitelline/choriovitelline placentae; this belt of villi is referred to as the __1__. On either side of the __1__, the cranial and caudal thirds of the chorionic sac remain free of villi (despite the fact that the __2__ grows into and vascularizes the ends of the chorionic sac); these smooth regions are referred to as the __3__. | 1. Chorion frondosum
2. allantois
3. Chorion laeve |
| The villi of the Chorion frondosum are vascularized by branches of the ____ arteries and become profusely branched. They then either erode the uterine epithelium and penetrate into the subepithelial ____ ____, or project into the openings of the ____ ____. | umbilical
connective tissue
uterine glands |
| Erosion of the uterine epithelium is initiated when the cells at the tips of the chorionic villi stimulate the maternal cells to become (1). The (1) cells then become (2) and are desquamated, together with some sub-epithelial (3). This erosion of the uterine epithelium also causes some damage to the maternal (4). The resulting hemorrhage adds blood cells to the mass of cellular debris that is beginning to form; however, most of the blood accumulates on the borders of the Chorion frondosum (i.e. between the Chorion frondosum and Chorion laeve). This accumulation forms two bands of clotted blood, which are referred to as (5). Together with the secretions of the uterine glands, the mass of cellular debris is absorbed as (6) by the cells at the tips of the chorionic villi. | 1. polyploid (state of a cell or organism having more than two paired sets of chromosomes)
2. pycnotic (condensation of chromatin in the nucleus of a cell undergoing necrosis)
3. connective tissue
4. capillaries
5. marginal hematomas
6. histotrophe |
| Apart from the initial minor damage, the maternal capillaries are not harmed by the penetrating chorionic villi; instead, the capillaries form labyrinthine networks between the villi. Each capillary network becomes surrounded by (1). The (1) is a fused mass of chorionic cells originating from the bases of the villi; the cells lose their internal walls and form a (2) (see Figs. 39 and 40). The (1) is particularly rich in mitochondria and is responsible for (3) nutrition. | 1. syntrophoblast
2. syncytium
3. hemotrophic |
| The capillary endothelium is separated from the syntrophoblast by an amorphous layer known as the (1) (see Fig. 40); it is thought that this layer is derived from the endothelial basal lamina. The (1) becomes more distinct (histologically) as gestation advances. Occasionally, maternal fibroblasts remain between the endothelium and the (1). These cells are known as (2) cells and are small and inconspicuous in the dog (see Fig. 40). However, in the cat, they are large, swollen polygonal cells containing (3). | 1. interstitial membrane
2. decidua
3. glycogen |
| Isolated single (lighter-staining) chorionic cells lie immediately peripheral to the syntrophoblast. These cells constitute the ____; they are reserve cells and can contribute to the syntrophoblast after mitotic division (see Fig. 40). | cytotrophoblast |
| The chorionic villi which project into the uterine glands effectively block their openings. Since the glands continue functioning, their ducts become filled with secretion and dilate. These enlarged ducts are referred to as the so-called (1) of the placenta (see Fig. 39). The obstructing chorionic villi absorb the accumulated secretion as (2). Adjacent (1) are separated by endometrial (3) (the maternal blood vessels en route to the syntrophoblast region run in these (3)). The uterine glands, which are greatly enlarged in the placental zone, are separated from the (1) by a layer of condensed connective tissue; this layer is known as the (4). | 1. gland rooms
2. histotrophe
3. septa
4. glandular covering layer |
| Name the 3 histological zones of the zonal placenta. | Compact Zone
Detritus Zone
Spongy Zone |
| Describe the Compact zone of the Zonal placenta. | Region of maternal capillaries, syntrophoblast and cytotrophoblast.
Has a relatively firm nature. |
| Describe the Detritus zone of the Zonal placenta. | Region where the tips of the chorionic villi are surrounded by cellular debris. |
| Describe the Spongy zone of the Zonal placenta. | Region of gland rooms and endometrial septa.
Has a relatively yielding nature. |
| The compact and spongy zones are functionally connected by the (1) that run through the detritus zone. As the pregnancy advances, the (2) zone expands at the expense of the (3) zone. In the cat, the (3) zone is not very well developed because the deeper parts of the gland rooms are not particularly dilated; the (4) is also less clearly defined. | 1. maternal blood vessels
2. compact
3. spongy
4. glandular covering layer |
| The marginal hematomas form two raised ridges on either side of the (1) (see Figs. 38/39). The clotted blood in the hematomas begins to degenerate and is absorbed by the overlying (2) as (3). The marginal hematomas usually have a greenish colour due to the presence of (4) pigment (a breakdown product of hemoglobin). In the cat, small marginal hematomas only form towards the end of pregnancy (from about day (5)) and are (6) in colour. The cat also has small hemorrhages (so-called (7) hematomas) scattered through-out the placental region; they are also (6) in colour and are absorbed as (3). | 1. Chorion frondosum
2. Chorion laeve
3. histotrophe
4. hemochlorin
5. 53
6. brownish/brown
7. labyrinthine |
| In both the dog and cat, areas for histotrophe absorption develop between the ____ and the ____; these areas resemble the ____ seen in the pig. | Chorion laeve
endometrium
areolae |
| At partus, the endometrial (1) degenerate just above the (2). The (3) of the placenta is thus desquamated and departs with the fetal membranes. The uterine epithelium then regenerates and replaces the lost tissue. The actual tissue loss at partus is relatively minor compared to that lost during placental development. | 1. septa
2. glandular covering layer
3. Pars uterina |
| The umbilical cord is relatively short: it is about one ___ and one ___ the neonatal body length in the dog and cat respectively. | 1/2
1/3 |
| What structures are present in the carnivore umbilical cord? | 1. paired vitelline arteries and veins
2. allantoic duct
3. paired umbilical arteries and veins (the latter fuse to form the left umbilical vein before reaching the umbilicus)
4. The vitelline duct may still be present but it usually closes early. |
| Does the carnivore umbilical cord have a natural point of rupture? | No, it must be bitten through by the mother |
| Classify the carnivore placenta. | 1. bi- and trilaminar vitelline (initially)
2. choriovitelline (later)
3. chorioallantoic (finally)
4. deciduate
5. zonary
6. endotheliochorial |
