Embryology Flashcards

(68 cards)

1
Q

What are the four development periods?

A

Germinal
Embryonic
Fetal
Postnatal

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2
Q

What is the origin of gametes?

A

Primordial germ cells

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3
Q

What are the five phases of spermatogenesis?

A
Multiplication phase
Growth phase
Maturation phase
Transformation phase/ speriogenesis
Liberation phase/ spermiation
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4
Q

Describe the maturation phase in spermatogenesis

A

Spermatogonia (diploid) becomes primary spermatocyte (diploid) after undergoing meiosis 1 they become haploid cells called secundary spermatocytes. After mitosis 2 they become early spermatids

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5
Q

Describe the transformation phase

A
Formation of acrosome (golgi)
Condensation of nuclear chromatin
Mid piece (mitochondria)
Residual body (cytoplasm)
Growth of the tail (centrioles)
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6
Q

Describe the spermiation/liberation phase

A

The spermatozoa are released into the lumen of seminifourous tubules and move to the epididymis

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7
Q

Describe the structure and f the mature spermatozoa

A

Head- nucleus and acrosome
Neck- distal and axial centrioles
Middle piece- axial filament, mitochondrial sheath and Jensens ring
Flagellum- main portion and end piece

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8
Q

What does semen consist of?

A

Spermatozoa and seminal plasma

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9
Q

Is there any correlation between semen volume and sperm count?

A

No, the more ejaculated volume the less sperms
Pig has largest volume, less sperms 200/250’
Rooster small volume, highest sperms 1/3,500’

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10
Q

What are the different type of defects that spermatozoa can have?

A

Compensable- the sperm is still funtionable
Uncompensable- the sperm will not be functioning
Can affect head or tail

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11
Q

What are the phases of oogenesis?

A

Multiplication phase
Growth phase
Maturation phase

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12
Q

Describe the multiplication phase in oogenesis

A

Happens before birth
The stem cell called oogomium
Primary oocyte (diploid) in primordial follicle

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13
Q

Describe the growth phase in oogenesis

A

The primary oocyte is arrested in prophase 1 at birth, primordial follicle
In puberty the follicle grows, primary follicle with zona pellucida
Tertiary follicle (graafian)

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14
Q

Describe the maturation phase

A

Meiosis 1 completed, first polar body

Secondary oocyte arrested in metaphase 2

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15
Q

What does the Graafian follicle contain?

A
Theca interna and theca externa 
Basal membrane/laminae 
Granulosa cells
Follicular antrum 
Corona radiata 
Zona pellucida
Secondary oocyte
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16
Q

Describe the ovulation

A

The follicle ruptures, releases the ovum that contains corona radiata, zona pellucida and the nucleus
If fecundated corpus luteum persists
No fecundation = corpus albicans

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17
Q

Describe the different types of eggs

A

Alecithal
Oligoceithal
Telolecithal

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18
Q

What is a telolecithal egg

A

Found in birds, reptiles, fish

One large yolk at one pole of the egg

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19
Q

What are the different parts of avian eggs?

A
The oocyte (oolemma, formative cytop+ nucleus, white and yellow yolk)
Vitelline membrane
Tertiary membranes (albumen, chalazae, inner and outer shell membranes, shell)
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20
Q

What are the six main facts of fecundation?

A
Insemination
Approximation of gametes
Spermatozoa capacitation
Spermatozoa penetration
Fusion of cells
Fusion of pronuclei
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21
Q

Which species has the most or less chromosomes?

A

Dog has most-78
Equine and rum app- 60
Pig and cat has less- 38

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22
Q

How can insemination occur?

A

Natural

Artificial

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23
Q

Where does the sperm meet the egg for fecundation?

A

In the ampulla

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24
Q

What are the phases of spermatozoa activation?

A

Adherence to zona pellucida
Acrosome reaction
Acrosomal filament

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25
What are the phases of oocyte activation?
Fecundation cone Fusion of membranes Block to polyspermy (fecundation membrane)
26
Describe the spermatozoa activation
``` The sperm is activated by female reproduction tract Sperm binds to zona pellucida Acrosomal reaction Sperm lyses hole in zona pellucida Sperm and egg membrane fuses ```
27
Describe the oocyte activation
The adherence of the sperm to zona pellucida and the egg plasma membrane causes the membrane to release cortical granules and withdraw the microvilies. The membrane thickens and creates a hyaline layer in plasma membrane that blocks the entrance of more sperms
28
Describe the fusion of cells and joining of pronuclei
As the sperm is fused to the egg membrane it releases its nucleus into the egg cell, where it fuses with the egg nucleus and becomes a zygote nucleus
29
What are the consequences of fecundation?
It restores the diploid number of chromosome (n from sperm+n from egg) It determines the sex of the individual Initiates the further development
30
What are the factors affecting fecundation?
Number, concentration and vitality of sperm | Vitality of oocyte
31
Where does fecundation occur in birds?
Infundibulum
32
Which are the first divisions in the germinal period?
Segmentation/cleavage Morulation Blastulation
33
Describe the cleavage/segmentation in meroblastic division
In birds, reptiles and fish One large cell and further division creates smaller cells Partial cleavage, unequal blastomeres
34
Describe the holoblastic division in segmentation/cleavage
All cells are of same size Total cleavage, equally sized blastomeres In mammals, nematodes
35
What happens during cleavage?
The zygote divides into two blastomeres, which continue to divide until it creates a morula (16-32 cells)within the zona pellucida. This continues creating a hollow ball of cells, blastula/blastocyst. The inner cavity called blastocoele
36
Describe the first divisions in poultry
``` It is meroblastic, partial cleavage creating a subgerminal cavity Area pellucida (the outer layer, covering the subgerminal cavity) Area opaca (underneath the subgerminal cavity) ```
37
Describe the blastulation in poultry
Delamination/forming of hypoblast (the under most layer of cells) Creating a subgerminal cavity between epiblasts and zona opaca. Hypoblast cells migrate from the epiblasts posterity zona marginal to form a hypoblast layer now being the lower margin of the created blastocoele
38
Describe the blastulation of mammals
Formation/delamination of the hypoblast The blastocyst with its outer layer of zona pellucida and inner layer of trophoblasts creates a cavity/blastocele. Epiblasts create a inner cell mass, that are lines with hypoblast which continue to cover the outside of blastocele. The blastocyst then hatches from zona pellucida
39
Describe the gastrulation in poultry
``` Formation of the primitive streak where cells migrate to form an invard shape, the epiblast Forming the three blastodermic layers -endoderm -mesoderm -ectoderm ```
40
What are the three blastoderm layers?
Ectoderm Mesoderm Endoderm
41
What are the deratives from the ectodermic (outermost) layer?
Neural plate Neural groove Neural tube Neural crest
42
Describe the process of the folding of the ectoderm
The open neural plate has ectoderm, neural plate borders and a neural plate. The neural plate borders joins/folds to create a groove/crest that when fused is the neural tube Three layers are formed- ectoderm, neural crest and neural tube
43
Describe the different deratives of the ectoderm and what they give rise to
Neural tube- brain, spinal chord and deratives Neural crest- ganglia, adrenal marrow, Schwann cells, microclimate, meninges, cephalic connective tissue, odontoblasts Embryonary ectoderm- epidermis, hair, feathers, glands, sense organs Extraembryonary ectoderm- chorion and amnion
44
What are the deratives of the mesoderm?
``` Notochord Paraaxial mesoderm (somites) Intermediate mesoderm (kidneys, gonads) Lateral plate (splachnopleura, somatopleura) ```
45
What is the notocord?
Derives from mesoderm | Cartilaginous flexible rod in all chordate
46
What are the parts of the paraxial mesoderm and what does it give rise to?
``` The head The somites Sclerotome- axial skeleton Dermatome- dermis and subcutaneous conn. Tissue Myotome- skeletal muscle ```
47
What does the intermediate mesoderm give rise to?
Urogenital system
48
What does the lateral plates give rise to?
Somatopleura- lining of pleural, pericardial and peritoneal cavity, amnios and chorion Splachnopleura- lining of pleural peritoneal cavity, heart, blood and endothelial cells, adrenal cortex, connective tissue and gut smooth muscle Extraembryonic
49
What are the deratives of the endoderm?
Gastrointestinal tract and annex glands (liver, pancreas), respiratory system, allantios, vitelline vesicle, urinary bladder
50
What is the acquisition of the body shape?
``` Lengthening of body Body folding Embryo and annexes separation Tail formation Division into head and trunk Development of limbs ```
51
What are the three types of implantation?
Central (carnivore/ungulates, no covering of endometrium) Eccentric (rodents, partially covered) Interstitial (primes/human/guinea pigs, totally covered)
52
What is the vitelline vesicle and what gives rise to it?
The yolk | Endoderm (hypoblast) and splachneoplura
53
What is amnion and chorion in poultry and what gives rise to it?
Chorion is the outermost layer/membrane Amnion covers the fetus, a sac with fluid that fetus floats in Derives from ectoderm and somatopleura
54
What is the amnion and chorion in mammals and where does it derive from?
Amnion- the membrane that are closest to the fetus, derives from ectoderm and somatopleura Chorion- the outermost fetal membrane, derives from trophoblasts and somatopleura
55
Describe the allantois in poultry
Makes out the circulatory system driven by the embryo, finally completely surrounding the embryo
56
What is the allantois function in mammals?
Surrounding the fetus and connects to it via the umbilical chord, makes out the placenta
57
What is the uterine vs fetal placenta?
Uterine placenta- modified uterine mucosa | Fetal placenta- chorionic vili (leave=smooth, frondosum=rough)
58
What are the five classifications of placenta?
``` Complete diffuse (only frondosum) Incomplete diffuse (frondosum in distal parts, leave in middle) Cotyledonary (cotelydon+caruncle makes out placentoma) Zonary (leave in distal parts, frondosum in middle) Discoidal (one disc like placenta) ```
59
What are the layers separating fetal and maternal blood?
Fetus- chorionic epithelium, connective tissue, endothelium | Maternal- endometrial epithelium, connective tissue, endothelium
60
What are the layers of epitheliochorial?
Epithelium, connective tissue, endothelium in both fetus and mother 3+3 layers In equine, cow, pig Sheep and goat partially
61
What are the layers of syndesmochorial?
Fetus- epithelium, connective tissue, endothelium Mother- connective tissue, endothelium 3+2 layers In sheep and goat, partially
62
What is the layers of endotheliochorial?
Fetus- epithelial, connective tissue, endothelium Mother-endothelium 3+1 layers In carnivores
63
What are the layers of haemochorial?
Only fetal layers- epithelium, connective tissue, endothelium 3 layers In rodents, primates, human
64
What are the two types of uterine mucosa destruction?
Deciduate (endotheliochondral placentas) | Adeciduate (epitheliochondral placentas)
65
What mechanisms/processes can interfere with development?
``` Cellular differentiation Patterning Cell migration Growth Cell death ```
66
What are hox genes?
Related genes controlling development of body in embryo
67
What is teratology?
Study of abnormalities of physical development
68
What can cause congenital disorders?
Genetic/chromosomal origin | Environmental causes