Fertilization, MRP, Placentation

Question 1

__________ is the fertilization of an oocyte by more than one spermatozoon, resulting in embryo death

Answer 1

polyspermy

Question 2

T/F: Zygote is unicellular. Embryo is multicellular

Answer 2

True

Question 3

After hatching, the conceptus undergoes massive growth. For example, in the cow at day 13 the blastocyst is ~3 mm in diameter. During the next four days, the cow blastocyst will become 250 mm in length and will appear as a __________

Answer 3

filamentous thread

Question 4

Which fetal membrane is shown in the picture?

Answer 4

amnion

Question 5

Fusion of the male and female pronuclei is termed:

Answer 5

syngamy

This is the final setp of fertilization. Following syngamy, the zygote enters the first stages of embryogenesis.

Question 6

Endometrial Cups in the mare produce:

Answer 6

equine chorionic gonadotropic (eCG)

helps to luteinize secondary corpora lutea in the mare

Question 7

In all domestic animals, the __________ is the origin of the placenta

Answer 7

chorioallantois

Question 8

What is the most accurate blood test you can run in the bitch to detect pregnancy?

Answer 8

relaxin

Question 9

Which of the following structures found in the adult mammal do not originate from the embryological mesoderm layer?

• Gonads and cervix
• Accessory gland
• Clitoris and vestibule
• Ductus deferens

Answer 9

Clitoris and vestibule

originate from the ectoderm

Question 10

The functional unit of the placenta is the __________

Answer 10

chorionic villi

Villi may be grouped together into microscopic groups (microcotyledons) or macroscopic groups (cotyledons)

Question 11

A cotyledonary placenta is seen in which species?

Answer 11

ruminants

Multiple, discrete areas of attachment called cotyledons are formed by interaction of patches of allantochorion with endometrium. The fetal portions of this type of placenta are called cotyledons, the maternal contact sites caruncles and the cotyledon- caruncle complex a placentome. This type of placentation is seen in ruminants

Question 12

What classification of placenta has 5 layers (2 from the mother, 3 from the fetus)?

Answer 12

endotheliochorial

dog, cat, ferret

Question 13

What classification of placenta has 6 layers (3 from the mother, 3 from the fetus)?

Answer 13

epitheliochorial

cow, ewe, doe, deer

Question 14

In the preattachment development of the embryo, when a distinct cavity is recognizable, the embryo is called a blastocyst. The embryo becomes partitioned into two distinct cellular populations: the __________ and the __________

Answer 14

In the preattachment development of the embryo, when a distinct cavity is recognizable, the embryo is called a blastocyst. The embryo becomes partitioned into two distinct cellular populations: the inner cell mass and the trophoblast

Question 15

The process whereby spermatozoa acquire fertility in the female reproductive tract is termed:

Answer 15

capacitation

Question 16

What are the three ‘barriers to fertilization’?

Answer 16

• Cumulus cells
• Zona pellucida
• Oocyte membrane (oolemma)

Question 17

T/F: MRP in the mare is characterized by a spherical conceptus migrating throughout the uterus

Answer 17

True

In the mare, the presence of the conceptus prevents luteolysis. Also, in the presence of the conceptus, endometrial production of PGF_2a is significantly reduced. A unique feature of maternal recognition of pregnancy in the mare is that the conceptus inust migrate within the uterus from one uterine horn to the other.

Question 18

A zonary placenta is seen in which species?

Answer 18

dogs and cats (and seals, bears, and elephants)

The placenta takes the form of a complete or incomplete band of tissue surrounding the fetus. Seen in carnivores like dogs and cats, seals, bears and elephants.

Question 19

In the preattachment development of the embryo, when a solid ball of cells is formed and individual blastomeres can no longer be counted accurately, the early embryo is called a __________

Answer 19

morula

Question 20

A diffuse placenta is seen in which species?

Answer 20

horses, pigs, camelids

Question 21

T/F: Zygote is multicellular. Embryo is unicellular

Answer 21

False

Zygote is unicellular. Embryo is multicellular

Question 22

What is the mechanism for maternal recognition of pregnancy in the sow?

• INF-T synthesis
• Estrogen sulphate production
• Migration of embryo
• Only zygote enter the uterus

Answer 22

estrogen sulphate production

Question 23

Which one of the following animals is not an induced ovulator?

• Rabbit
• Camel
• Cat
• Dog

Answer 23

dog

Question 24

The conceptus of the pig produces __________ that serves as the signal for maternal recognition of pregnancy

Answer 24

estradiol

Question 25

The main driver for the onset of puberty in mammals is:

Answer 25

**ability of the hypothalamic neurons to produce sufficient GnRH**

Question 26

\_\_\_\_\_\_\_\_\_\_ is the ability of a single blastomere to develop into a fully formed individual animal

Answer 26

**totipotency**

Question 27

What happens if maternal recognition of pregnancy does not occur in a timely manner?

Answer 27

**termination of pregnancy** * In order for the events of early embryogenesis to continue into an established pregnancy, luteolysis must be prevented. Progesterone must be maintained at sufficiently high levels so that embryogenesis and attachment of the developing conceptus to the endometrium can take place.* * If an adequate signal is not delivered in a timely manner, the dam will experience luteolysis, progesterone concentrations will decline, and pregnancy will be terminated.*

Question 28

What four steps must be acheived before the embryo can attach to the uterus?

Answer 28

1. **Development within the confines of the zona pellucida** 2. **Hatching of the blastocyst from the zona pellucida** 3. **Maternal recognition of pregnancy** 4. **Formation of the extraembryonic membranes**

Question 29

In the preattachment development of the embryo, when a distinct cavity is recognizable, the embryo is called a blastocyst. The embryo becomes partitioned into two distinct cellular populations: the inner cell mass and the trophoblast. The inner cell mass will give rise to the:

Answer 29

**body of the embryo**

Question 30

A **discoid placenta** is seen in which species?

Answer 30

**primates and rodents** *A single placenta is formed and is discoid in shape*

Question 31

In the preattachment development of the embryo, when a distinct cavity is recognizable, the embryo is called a \_\_\_\_\_\_\_\_\_\_

Answer 31

**blastocyst**

Question 32

After membrane fusion, the oocyte undergoes a series of changes that prepare it for early embryogenesis. The most recognizable is the \_\_\_\_\_\_\_\_\_\_, which prevents penetration by additional spermatozoa

Answer 32

**cortical reaction**

Question 33

T/F: Maternal recognition of pregnancy in the dog and the cat does not necessarily require a signal from the conceptus

Answer 33

**True** * *The bitch CL has similar lifespan in pregnant and non-pregnant bitches* * *The queen has similar lifespan of CL in pregnant and induced ovulation*

Question 34

What protein is produced by the blastocyst in ruminants to signal for prevention of luteolysis?

Answer 34

**Interferon tau (IFN-T)** *IFN-T inhibits the formation of Oxytocin receptors so that Oxytocin can not signal PGF synthesis. IFN also promotes protein synthesis by uterine glands (believed to be critical to preimplantation embryonic survival)*

Question 35

In the preattachment development of the embryo, when a distinct cavity is recognizable, the embryo is called a blastocyst. The embryo becomes partitioned into two distinct cellular populations: the inner cell mass and the trophoblast. The trophoblastic cells will give rise to the:

Answer 35

**chorion** *The chorion will become the fetal component of the placenta*

Question 36

T/F: MRP in the sow is characterized by the presence of Interferon tau (IFN-T)

Answer 36

**False** ## Footnote *MRP in the sow is characterized by estradiol, re-routing of PGF_2a, embryo elongation, and 4 conceptuses (2 in each horn)*

Question 37

The dog and the cat have an endotheliochorial placenta. This placental classification involved complete erosion of the:

Answer 37

**endometrial epithelium**

Question 38

What type of placenta is shown here?

Answer 38

**Zonary**