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128 Cards in this Set
- Front
- Back
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What are the 3 periods of the Prenatal Period?
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1) Pre-embryonic
2) Embryonic 3) Fetal Peroid |
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Pre-embryonic period is?
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The period from development of the gametes (gametogenesis) up to implantation
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Embryonic Period is?
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The period of implantation to the origin of the primordia of the organs and the formation of the basic body form
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Fetal Period is?
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The period of growth and maturation of the organ-system to become competent to assume their specialized functions
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What is an embryo?
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The developing offspring during the embryonic period
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What is a fetus?
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The developing offspring during the fetal period
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What does the term conceptus describe?
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It is used to describe the embryo/fetus and its membranes
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What is fertilization?
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Fertilization is the fusion of the sperm and ovum to initiate the development of a new individual
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What is ovulation?
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Ovulation is the release of primary or secondary oocytes from the surface of the ovary. It precedes fertilization
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What is insemination?
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Insemination is the deposition of sperms into the female genital tract
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Where does fertilization occur?
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Fertilization occurs in the uterine tube
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What the two main hormones in ovulation?
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Follicle stimulating hormone (FSH) and Luteinizing Hormone (LH)
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What is the corpus luteum and what is its function?
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Corpus luteum is an important endocrine structure formed from the ruptured follicles.
It secretes progesterone which produces uterine changes that facilitate the implantation and maintenance of the conceptus |
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Ovulation occurs spontaneously in most mammals except in what two animals?
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The cat and rabbit ovulation is induced by coitus
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What is a polytocous animal and what give some examples.
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Polytocous animals release more than one oocyte during ovulation usually from separate follicles.
examples are: bitch, sow, cat, and small ruminants |
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What is a monotocous animal?
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An animal that releases only one oocyte during ovulation
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How long are sperm viable in the fowl and turkey?
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Sperm viability
Fowl: 32 Days Turkey: 70 Days |
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What is capacitation?
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The reaction that occurs in the sperm and removes the glycoprotein coat and seminal plasma protein from the plasma membranes that overlies the acrosomal region of the spermatozoa
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What is the acrosomal reaction?
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The acrosomal reaction occurs when the sperm releases enzymes (hyaluronidase and trypsin like substance) in the acrosome. The action of these enzymes facilitate the penetration of the oocyte barriers
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What is polyspermy and how is it usually prevented?
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Polyspermy is when more than one sperm enters the oocyte
It is prevented by the formation of the Fertilization Membrane from the Zona Reaction |
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What are the main events of fertilization?
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1) Capacitation of Sperm
2) Acrosome Reaction 3) Sperm Penetrates Oocyte 4) Pronuclei form 5) Duplication of DNA 6) Two Cell stage 7) Fusion |
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Describe monozygous twinning
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When one ovum is fertilized but subsequently divides at the blastocyst stage into two genetically identical mass, therefore always of the same sex and same blood group
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Describe dizygous twinning
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When two separate ova are fertilized
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What is freemartin?
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Occurs in dizygous twins (cattle) the development of a common circulation and the twins are opposite sex. The testosterone produced in the male retards the development of the female causing her to be infertile
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What is superfecundation?
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Impregnation by successive acts of coitus, of two or more ovum that were liberated at approximately the same time, by two or more different males (cats and dogs)
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What is superfetation?
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When a pregnant female ovulates, conceives and produce a second younger fetus (pigs)
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Gestation Period of each animals
Mare, Cow, Ewe, Sow, Bitch, Queen |
Mare: 335-345
Cow: 279-282 Ewe: 148-150 Sow: 114-120 Bitch: 60-65 Queen: 60 |
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What is cleavage?
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Cleavage is a series of mitotic cell divisions, without overall increase in the size of the zygote, which is still enveloped by zona pellucida. Results in many smaller cells called blastmomeres
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What is holoblastic cleavage?
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In mammals where a small amount of yolk is present (equally distributed) there is a complete division of zygote. Thus cleavage is total or holoblastic
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What is meroblastic cleavage?
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In birds, the massive amount of yolk prevent complete division of the zygote thus the cleavage is partial or meroblastic
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What is a morula?
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After 4 to 6 divisions, zygote results in the formation of a solid cluster of cells called a morula
- It consists of 16-64cells in most domestic animals |
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What is a blastocoel?
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The secretion from the blastomeres collected within a morula, cause a rupture of the zona pellucida and formation of fluid filled cavity called the blastocoel
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What is the inner cell mass?
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Also known as the blastodisc or embryonic disc, They are the small area of cells that become larger than the rest of teh cells from which the embryo will develop
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What is a trophoblast?
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The cells on the periphery of the blastocyst, they facilitate the absorption of nutrients early in development
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What is the result of gastrulation?
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The embryonic disc (inner cell mass) become rearranged to form three separate layers called the germ layers
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What are the three germ layers formed from gastrulation?
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The outermost layer - Ectoderm
The innermost layer - Endoderm The layer between them - Mesoderm |
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Describe the formation of the Endoderm.
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A group of inner cell mass cells delaminate from the inner surface to from a continuous sheet lining the interior of the blastocyst
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What is the primitive gut (archenteron)?
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The cavity that is enclosed by the formation of the endoderm
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Describe the formation of the ectoderm.
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The cells in the upper layer of the inner cell mass undergo expansion to form the ectoderm
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What is the notochord?
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The notochord is formed when some of the mesodermal cells are arranged on the dorsal midline of the body
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How is the Neural Plate (neural ectoderm) formed?
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The notochord inducces the ectoderm to form the neural ectoderm.
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What is the fate of the notochord in an adult?
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It persists as the nuclear propolsus in the intervertebral disc
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What is the somatopleure made of?
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Somatic Mesoderm + Ectoderm
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What is the splanchnopleure made of?
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Splanchnic Mesoderm + Endoderm
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What is the paraxial mesoderm?
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The dorsally proliferating mesodermal cells on either side of the notochord become thickened to form the paraxial mesoderm
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What does the paraxial mesoderm give rise to?
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Somites
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What are the two layers of the lateral mesoderm split into?
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The lateral mesoderm is split into the somatic mesoderm and splanchnic mesoderm.
The somatic mesoderm is associated with the ectoderm to form the Somatopleure The Splanchnic Mesoderm is associated with the Endoderm to form the Splanchnopleure |
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What does the Paraxial Mesoderm later form?
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Forms a series of mesodermal thickenings called somites
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What do the somites differentiate into?
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Myotomes - associated muscles
Sclerotomes - vertebral column Dermatome - Connective tissue |
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How does the flat disc transform into a roughly curved cylindrical disc?
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Longitudinal and Transverse (lateral) folding
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Describe Longitudinal folding.
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Occurs in the cephalo-caudal direction. This folding is more pronounced in the cranial caudal end of the embry and leads to head and tail fold formation
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Describe Transverse (lateral) folding
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The embryonic disc obtains a cylindrical appearance and lateral and ventral body wall of the embryo is established
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What does the extra-embryonic splanchnopleure form?
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The yolksac and the allantois
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What does the Intraembryonic splanchnopleure form?
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The Gut
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What does the extra-embryonic somatopleure form?
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The amnion and chorion
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What does the intra-embryonic somatopleure form?
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Lateral and ventral body walls
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What is the Vitellointestinal Duct (yolk stalk)
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A duct through which the yolk sca communicates with the gut
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What does the umbilical cord contain?
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1) Yolk Sac
2) Vitelline Vessels 3) Allantois 4) Umbilical Vessels |
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What membrane does the chorion and amnion arise from?
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Somatopleure, specifically the extra-embryonic somatopleure
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What membrane does the Yolk sac and allantois arise from?
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Splanchnopleure, specifically the extra-embryonic splanchnopleure
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What is Hydroamnion?
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An excess amount of amniotic fluid
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What is it called when the chorion and allantois fuse?
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The chorion and allantois fuse to form the chorio-allantoic placenta.
Most common domestic animals have this - Dogs and horses have both chorio-allantoic and choriovitelline placentas but the chorio-vitelline regresses and only remains functional for sometime (first quarter of pregnancy) in dog and horses -Chickens have no placenta at all |
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What is it called when the chorion and vitelline (yolksac) fuse?
What animal is this found in? |
Choriovitelline placenta is formed from the fusion of the chorion and the yolk sac.
it is found in the dog and horse |
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Do chickens have Chorio-vitelline placentas chorio-allantoic placentas or do they have both?
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They have neither, Chickens do not have placentas
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What is hydroallantois?
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A defective chorio-allantoic placenta charactized by rapid accumulation of watery clear fluid build up
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What is Superficial implantation?
What animals does this occur in? |
The embryonic sac lies in the uterine lumen or cavity
Occurs in - ruminants, equines, porcine (pigs) |
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What is Eccentric implantation?
What animals does this occur in? |
The embryonic sac lies in a fold or pocket of uterine wall.
Occurs in - rats and squirrels |
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What is interstitial implantation?
What animals does this occur in? |
The embryonic sac penetrates and embedded into the uterine wall
Occurs in - guinea pig, carnivores, bats, humans |
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What does histrotrophic nutrition refer to?
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nutrition from secretion of uterus (endometrial) glands
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What does hemotrophic nutrition refer to?
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nutrition from the maternal circulation
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What are the implantation times for the cow and mare?
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Cow 25-30 Days
Mare 35-40 Days |
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What are the functions of the placenta?
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Nutrition
Respiration exchange of gases Excretion Placental barrier synthesis of hormones (estrogen, progesterone, gonadotropins) |
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Describe the placenta of
Sow/Mare in terms of 1) Shape of Placenta 2) Branching of Chorionic Villi 3) Loss of maternal tissue at partuition 4) Histological Layers |
1) Diffuse Placenta
2) Villous (Simple Chorionic Branching) 3) Non-deciduate 4) Epithelialchorial |
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Describe the placenta of
Ruminants in terms of 1) Shape of Placenta 2) Branching of Chorionic Villi 3) Loss of maternal tissue at partuition 4) Histological Layers |
1) Cotyledon
2) Villous (Simple Chorionc Branching) 3) Non-deciduate 4)Syndesmochorial |
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Describe the placenta of
Carnivores (dog and cats) in terms of 1) Shape of Placenta 2) Branching of Chorionic Villi 3) Loss of maternal tissue at partuition 4) Histological Layers |
1) Zonary
2) Labyrinthe 3) Deciduate 4) Endotheliochorial |
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Describe the placenta of
Monkeys, rodents, and bats in terms of 1) Shape of Placenta 2) Branching of Chorionic Villi 3) Loss of maternal tissue at partuition 4) Histological Layers |
1) Discoidal
2) Labyrinthe 3) Deciduate 4) Hemochorial |
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The Majority of causes of abnormal developments is?
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of Unknown origin
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What are the periods of susceptibility for the pre-natal periods in order of highest susceptibility to lowest?
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1) Highest is Embryonic Period
2) Second Highest is Fetal Period 3) Last is Pre-differentiation Peroid |
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What germ layer gives rise to the cardiovascular system?
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The Mesoderm, specifically the splanchnic mesoderm
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What are blood islands?
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They are collections of splanchnic mesodermal cells
Peripheral cells - vascular endothelium Central Cells - hemocytoblasts - blood cells |
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What do lymphoid cells give rise to?
What do myeloid cells give rise to? |
Lymphoid cells give rise to lymphoytes
Myeloid cells - everything else |
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What do the sinus horns give rise to?
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Right horn - sinus venerum
Left Horn - coronary sinus |
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Embryonic to Adult structure
What does the Truncus Arteriosis give rise to? |
1) Aorta
2) Pulmonary Artery |
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Embryonic to Adult structure
What does the Bulbus Cordis give rise to? |
1) Aorta
2) Pulmonary Artery 3) Conus Arteriousus |
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Embryonic to Adult structure
What does the Primitive Ventricle give rise to? |
Left and Right Ventricles
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Embryonic to Adult structure
What does the Primitive Atrium give rise to? |
Left and Right Atrium
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Embryonic to Adult structure
What does the Sinus Venosus give rise to? |
Right Horn - Sinus Venerum of right atrium
Left Horn - Coronary Sinus of right atrium |
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Adult to Embryonic structure
What does the Aorta arise from? |
1) Truncus Arteriosus
2) Bulbus Cordis |
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Adult to Embryonic structure
What does the Pulmonary Artery arise from? |
1) Truncus Arteriosus
2) Bulbus Cordis |
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Adult to Embryonic structure
What does the conus arteriosus arise from? |
Bulbus Cordis
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Adult to Embryonic structure
What does the left ventricle arise from? |
Primitive Ventricle
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Adult to Embryonic structure
What does the right ventricle arise from? |
1) Primitive Atrium
2) Bulbus Cordis |
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Adult to Embryonic structure
What does the left atrium arise from? |
1) Primitive Atrium
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Adult to Embryonic structure
What does the left atrium arise from? |
Primitive Atrium
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Adult to Embryonic structure
What does the Sinus Venerum of the Right atrium arise from? |
Right Horn of the Sinus Venosus
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Adult to Embryonic structure
What does the Coronary Sinus arise from? |
The left horn of the sinus venosus
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What are the four conditions of Tetrology of Fallot?
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1) Pulmonary Stenosis
2) Interventricular Defect 3) Dextroaorta 4) Right Ventricular Hypertrophy |
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What are the three conditions of Eisenmenger?
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1) Interventricular Septal Defect
2) Dextroaorta 3) Right Ventricular Hypertrophy Eisenmenger = Tetrology of Fallot - Pulmonary stenosis |
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Derivatives of Aortic Arches
What does the 1st, 2nd, and 5th |
Gives rise to nothing
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Derivatives of the Aortic Arches
What does the 3rd give rise to? |
Common/internal Carotid Arteries
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Derivatives of the Aortic Arches
What does the 4th give rise to? |
Right: Right Subclavian Artery
Left: Continues as descending aorta |
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Derivatives of the Aortic Arches
What does the 6th give rise to? |
Right and Left pulmonary artery
the left sixth retain its connection to the aorta as ductus arteriosus |
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What is a persistent right aortic arch and what does it result in?
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Persistent right aortic is when the right arch persists and causes obstruction of the heart and its base
-Causes a vascular ring abnormality |
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Describe patent ductus arteriosus
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Neonate ductus arterisus fails to close
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Branches of Dorsal Aorta
Dorsal Intersegmental Arteries |
Arise bilaterally between the somites and form the intercostal and lumbar arteries
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Branches of the Dorsal Aorta
Lateral Aortic Branches |
Supply the derivatives of the intermediate mesoderm and form renal, testicular or ovarian arteries
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Branches of the Dorsal Aorta
Ventral Aortic Branches |
Supply the splanchnic mesodermal and endodermal tissues of the thoracic and abdominal cavities.
These develop into bronch-esophageal and celiac and caudal mesenteric arteries |
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Describe the path of the fetal circulation of Oxygenated blood from the mother
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Oxygenated blood --> umbilical vein --> bypasses the liver via ductus venosus --> caudal vena cava --> right atrium --> foramen ovale
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Fetal Circulation Changes after Birth
Foramen Ovale becomes the... |
Fossa Ovalis
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Fetal Circulation Changes after Birth
Ductus Venosus becomes the... |
Ligamentum Venosus
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Fetal Circulation Changes after Birth
Ductus Arteriosus becomes the.. |
Ligmentum Arteriosus
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Fetal Circulation Changes after Birth
Umbilical Vein becomes the.. |
Round ligament of the liver
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Fetal Circulation Changes after Birth
Umbilical Artery becomes the... |
Round ligament of the bladder
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Development of the veins
The Cranial Cardinal Vein gives rise to the.. |
1) Brachio-cephalic vein
2) Cranial Vena Cava |
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Development of the veins
The Subcardinal Vein gives rise to the... |
1) Caudal Vena Cava
2) Renal Vein |
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Development of the veins
The Supracardinal vein comes together with the caudal cardinal vein to form the... |
Azygos vein
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Development of the veins
What only has a right azygos |
Horse and dog
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Development of the veins
What only has left azygos |
Pig
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Development of the veins
What has both left and right azygos veins? |
Ruminants
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Early Embryonic Circulation
Left and Right Vitelline Arteries give rise to what? |
Left: regresses
Right: Cranial Mesenteric Artery |
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Early Embryonic Circulation
Proximal and Distal Umbilical Artery gives rise to what? |
Proximal: External and Internal Illiac Arteries
Distal: Round ligament of the urinary bladder |
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What is unique about osteoclast structure and what type of cells do they arise from?
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Osteoclasts are multi-nucleated and they arise from monocytes
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Annulus Fibrosus precursor is...
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Mesenchyme of the sclerotome
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The Nuclear propolsus dvelops from what?
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The notochord
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All muscles (smooth, cardiac, and skeletal) come from the mesoderm. What are the exceptions?
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The muscles of the iris (sphincter and dilator pupillae originate from the optic cup
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What is a limb bud?
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Localized poliferization of mesoderm covered by ectoderm
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What is a limb field?
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an area of somatopleure committed to forming a limb
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Development of the base of the skull
What are the 4 bones in the skull that are developed by endochondrial ossification? |
1) temporal bone
2) occipital bone 3) Ethmoid 4) Sphenoid |
