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histo week 12 final
Terms in this set (61)
The primordial germ cells, which are destined to develop into gametes, are originated in the _________________, from where they migrate to get established in the developing gonad.
wall of the yolk sac
They go to the gonad (testes or ovary) and either enter gametogenesis or oogenesis (location of active division)
During spermiogenesis, what occurs to the following structures of the spermatid? (AKA what does each become?)
a. Chromatin content?
b. Golgi apparatus?
a. Chromatin content? Forms the bulk of the nucleus and concentrates at the HEAD of the sperm cell
b. Golgi apparatus? Concentrates and reorganizes to become the acrosomal CAP OVER THE HEAD
c. Centrioles? Moves away from the anterior and encircles the FLAGELLUM (this provides motility)
d. Mitochondria? Concentrates around the proximal part of the flagellum forming the MIDDLE PIECE
In most domestic animals what form of oocyte is released during ovulation?
a. What species are the exception?
a. Horses & Dogs: they release the primary oocyte (both meiotic divisions occur after stimulation of the penetrating sperm)
Which species contain the greatest number of chromosomes?
a. Which two species tie for the least number of chromosomes?
Dog (78 chromosomes/39 pairs)
a. Pig & Cat (38 chromosomes/19 pairs)
What two hormones control ovulation?
What structure has important endocrine function with its secretion of progesterone which functions to facilitate the implantation and maintenance of the conceptus?
What are the only 2 species that have non-spontaneous (induced) ovulation?
Rabbit & Cat:
this means the coitus stimulates the release of the oocyte! Ovulation is spontaneous in most other species.
What two domestic species are well known monotocous animals?
Horses & Cows (large ruminants)
(monotocous: release 1 oocyte each period)
In most species, sperm remains viable within the female genital tract for ____ days.
a. Which 2 domestic species are the exception?
b. Sperm may last up to 32 days in the fowl and 70 days in the turkey. What do birds contain that allows for this?
a. Horse/Dog: may survive up to 6-7 days
b. Sperm host glands which store and provide nutrients to the sperm
How long is the ovum viable after ovulation?
Where does fertilization normally occur in most species?
a. Which animals are the exception?
b. Where does fertilization occur for them?
Ampullary region of the uterine tube!
b. Where does fertilization occur for them? Infundibulum
_____________ involves removal of glycoprotein coat and seminal plasma protein from the plasma membranes that overlies the acrosomal region of the spermatozoa
Note that sperm must undergo this process in order to fertilize the ovum
Capacitation is followed by _____________________ which involves the release of ___________ which facilitate the penetration of the oocyte barriers.
acrosomal reaction enzymes
volves the release of enzymes which facilitate the penetration of the oocyte barriers. (Oocyte barriers: Corona radiata, zona pellucida and oocyte cell membrane). Enzymes: hyaluronidase and trypsin-like substance.
What occurs during the fertilization reaction?
a. What does this help prevent?
Fertilization membrane forms
a. Helps prevent further entry of the sperm into oocyte (polyspermy)
What occurs during the zona reaction?
a. What does this help to facilitate?
Chemical changes within the zona pellucida
a. Facilitates the fertilization reaction (prevention of polyspermy):
Zona pellucida changes structure and doesn't allow other sperm to enter
What form of twin results from one ovum being fertilized and subsequently dividing at the blastocyst stage into 2 generically identical masses?
a. Therefore, these twins are always of the same _____ and ___________
a. sex and blood group
What form of twin results from two separate ova being fertilized?
The result of a dizygotic pregnancy (one boy, one girl), in which the male sex hormone (testosterone) limits the sexual characteristics of the female fetus, leading to a sterile heifer
a. Ectopic pregnancy
What do we term the phenomenon in which more than one sperm penetrates the female germ cell?
d. Ectopic pregnancy
What term is defined as the impregnation by successive acts of coitus, of two or more ovum that were liberated at approximately the same time, by 2+ different males?
d. Dizygous twins
Typically, the bitch will be in heat for 6-7 days (in estrus), but fertilized by 2+ males in this time. In this case, we see ONE LITTER, but 2 DIFF MALES
What term is defined as the pregnant female ovulating, conceiving and producing a second younger fetus?
a. Monozygous twins
c. Dizygous twins
d. Ectopic pregnancy
usually ovulation does not occur during pregnancy, but in this case it does and mating takes place even though the female is already pregnant. In this case, you will have offspring from the previous estrus cycle and offspring from the second estrus cycle that took place during pregnancy. You will normally see some normal sized and some smaller sized babies.
In which species would you most likely see the following phenomenons?
a. Freemartin: cows
b. Polyspermy: pigs (&birds)
c. Superfecundation: dogs/cats
d. Superfetation: pigs
Match the species with the corresponding gestation period
1. Queen A. 335-345 days
2. Sow B. 60-65 days
3. Mare C. 60 days
4. Cow D. 114-120 days
5. Ewe E. 279-282 days
6. Bitch F. 148-150 days
1. Queen: 60 days (2 months) (C)
2. Sow: 114-120 days (4 months) (D)
3. Mare: 335-345 days (11 months) (A)
4. Cow: 279-282 days (9 months) (E)
5. Ewe: 148-150 days (5 months) (F)
6. Bitch: 60-65 days (2 months) (B)
Cleavage is the beginning of the _____________ of a multicellular organism. It is a serious of _______ cell divisions _________ overall increase in the size of the zygote, which is still enveloped by _______________. The first mitotic division occurs at the ___________ of the cytoplasm and the second division tends to be at the ______________ to the previous one.
Cleavage is the beginning of the development of a multicellular organism. It is a serious of mitotic cell divisions without overall increase in the size of the zygote, which is still enveloped by zona pellucida. The first mitotic division occurs at the long axis of the cytoplasm and the second division tends to be at the right angles(perpendicular) to the previous one.
No growth can occur if zona pellucida is still in tact!
T/F: the speed of division is directly proportional to the amount of yolk present
F: the speed of division is directly proportional to the amount of yolk present. Inversely proportional!
The more yolk there is the slower that region of the zygote takes to cleave. More yolk=Slower division
When cleavage results in the complete division of the zygote this is known as __________________
Are mammalian eggs holoblastic or meroblastic? What about bird eggs?
a. Mammalian eggs:
b. Bird eggs:
a. Holoblastic (total)
b. Meroblastic (partial)
What causes the incomplete partition of the zygote seen in meroblastic cleavage?
The abundance of yolk prevents complete division of the zygote
What is the name of the structure that results from 4-6 divisions of the zygote during cleavage?
Keep in mind that the zona pellucida must still be in tact in order to term it a morula! The zona pellucida is only in tact for 6 cell divisions.
What causes rupturing of the morula's zona pellucida?
Secretion from the blastomeres accumulate to cause the zona pellucida to rupture
Note that now that the zona pellucida is ruptured, growth can now occur.
What is the name of the fluid-filled cavity present within the blastula?
What is the name of the cells that lie at the periphery of the blastocyst and facilitate the absorption of nutrients early in development?
Describe the process of gastrulation: The _______________ becomes rearranged to form ___ separate layers called _____________
a. What are the germ layers from outermost to innermost?
embryonic disc (inner cell mass)
The cells that detach from the inner cell mass' inner surface generating a new continuous sheet that lines the interior of the blastocyst, forms what germ layer?
a. What is the name of it's enclosed cavity?
b. What is the name of the process by which cells detach from the inner cell mass?
Endoderm (innermost layer)
a. Primitive gut (archenteron)
The cells in the upper layer of the cell mass undergo considerable expansion and constitute what germ layer?
Ectoderm (outermost layer)
Formation of the mesoderm: What structures do the mesodermal cells in each of the following locations form?
a. Dorsal midline:
b. Parallel to central axis:
d. Between paraxial and lateral:
b. Paraxial mesoderm
c. Lateral mesoderm
d. Intermediate mesoderm
The notochord induces the ___________ to form the _________, which eventually gives rise to the ______________.
neural ectoderm (neural plate) neural tube
When the notochord regresses in the adult it persists as what structure?
Nucleus pulposus of the intervertebral disc
What two layers does the lateral mesoderm split into?
Somatic mesoderm & Splanchnic mesoderm
The somatic mesoderm is associated with the ________ to form the ______________.
The splanchnic mesoderm is associated with the __________ to form the ________________.
What mesodermal layer forms somites?
a. What are the 3 differentiations of somites? Give the respective tissue structures they form.
1. _____________, which forms:
2. _____________, which forms:
3. _____________, which forms:
1. Sclerotomeà - spinal cord
2. Myotomeàepimere -(epaxial)/hypomere (hypoaxial) muscles
3. Dermatomeà - dermis
Due to rapid growth of the __________________, it is transformed from ovoid into ______________ in shape, and then is transformed into a roughly _____________________ embryo during the establishment of the body form.
The part of the germ layer which underlies the embryonic disc is called ___________________________ whereas the cells lying peripherally under the trophoblast is called the __________________________.
intra-embryonic germ layer
extra-embryonic germ layer
What is the result of the folding of the following structures?
a. The intraembryonic somatopleure folds to form _______________________
b. The extraembryonic somatopleure folds to form _______________________
c. The intraembryonic splanchnopleure folds to form _____________________
d. The extraembryonic splanchnopleure folds to form _____________________
a. Lateral/Ventral body walls
d. Yolk sac/allantosis
What does the umbilical cord contain?
a. All fetal or extraembryonic membranes (amnion, chorion, yolk sac, allantois)
b. Yolk sac or vitelline blood vessels
c. Allantois or umbilical blood vessels
Limb buds appear as a single paddle-shaped outgrowth of the
What structure accumulated fluid to form a fluid-filled sac around the embryo?
c. Yolk sac
What is the name of the structure that forms from the temporary contact between the yolk sac and the chorion?
a. This structure typically regresses quickly, but will remain relatively active in what 2 species?
a. Dogs & Horses
What extraembryonic/fetal membrane develops from the extraembryonic splanchnopleure as a diverticulum of the hindgut?
b. Yolk sac
What structure is considered an excretory produce, described as a circular, flat, smooth body found in the allantoic fluid of mares and bovine? Hippomane
What are the 3 types of implantation?
a. ________________: embryonic sac lies in uterine lumen/cavity
i. Commonly seen in which species?
b. ________________: embryonic sac lies in a fold/pocket of uterine wall
c. ________________: embryonic sac penetrates & is embedded into uterine wall
i. Commonly seen in which species?
a. Superficial/Central: embryonic sac lies in uterine lumen/cavity
i. Commonly seen in which species? Ruminants, horse, pig
b. Eccentric: embryonic sac lies in a fold/pocket of uterine wall
c. Interstitial: embryonic sac penetrates & is embedded into uterine wall
i. Commonly seen in which species? Carnivores, guinea pigs, bats, humans
Which 2 species tie for the shortest time of implantation?
a. What species has the longest time till implantation?
Sow/Queen (pig/cat): 13-14d
a. Mare: 5 weeks
What are the 5 ways in which we classify the placenta?
a. Fetal membranes involved
b. Shape of placenta
c. Branching of chorionic villi
d. Loss of maternal tissues at parturition
e. Histological layers
What are the 2 classifications of placentation based on fetal membranes involved?
a. _______________________: yolk sac + chorion
b. _______________________: allantois + chorion
i. Ruminant, pig, Carnivore, horse
**Notice Horse/Dog have BOTH
What are the 4 classifications of placentation based on shape?
a. _______________________: uniformly distributed
b. _______________________: tufts of chorionic villi attach to caruncles
c. _______________________: chorionic villi form band around chorionic sac
d. _______________________: chorionic villi form 1-2 disc shaped area
i. Primates, rodents, bats
What are the 2 classifications of placentation based on branching of chorionic villi?
a. _______________________: simple branching
b. _______________________: complex anastomotic branching
i. Pig, horse, ruminant
i. Carnivores, primates
What are the 2 classifications of placentation based on maternal tissue loss at parturition?
a. _______________________: extensive loss
b. _______________________: little loss
i. Carnivores, primates
i. Pig, horse, ruminant
What are the 4 classifications of placentation based on histological relations? (May be helpful to answer #60/61 first)
a. _______________________: all 6 layers present
b. _______________________: 5 layers present
c. _______________________: 4 layers present
d. _______________________: 3 layers present
a. Epitheliochorial: chorionic epithelium makes contact with uterine epithelium
i. Pig, horse
b. Syndesmochorial: chorionic epithelium makes contact with uterine CT
b. Endotheliochorial: chorionic epithelium makes contact with endothelium of BV of uterus
c. Hemochorial: chorionic epithelium makes contact with uterine blood
c. "Epic Sports End Happily"
There are 6 layers separating the fetal blood from maternal blood:
What are the 3 histological layers found on the fetal side of the placenta?
a. Chorionic (villous) epithelium
b. Fetal (villous) CT
c. Endothelium of allantois BV
What are the 3 histological layers found on the maternal side of the placenta?
a. Uterine epithelium
b. Uterine CT
c. Endothelium of BV of uterus
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