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URO > Group 2 - Sperm to Establishment of Preg - COMPLETE*** > Flashcards

Group 2 - Sperm to Establishment of Preg - COMPLETE*** Flashcards

1
Q

What is Spermatogenesis?

A

a process where spermatozoa are formed

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2
Q

Spermatogenesis: How long generally does it take?
- Where does it take place?

A

5-9 weeks

in the seminiferous tubules

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3
Q

Spermatogenesis: State the names of the spermatozoa starting with the earliest one 7

A

A spermatogonia
Intermediate spermatogonia
B spermatogonia
primary spermatocytes
secondary spermatocytes
spermatids
spermatozoa

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4
Q

Spermatogenesis: State the 3 general stages and explain what happens in each

A

proliferation - A spermatogonia undergo mitotic divisions to produce B spermatogonia

meiosis - this produces haploid spermatids and crossing over ensures their genetic heterogeneity

differentiation - this forms a cell capable of fertilisation

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5
Q

Spermatogenesis: Where in the seminiferous tubules does it start?
- what happens first?
- What is maintained?
- What are the cells connected by and what does this enable them to do?

A

at the most lateral edge

A spermatogonia undergo mitosis

a pool of stem cells

intercellular bridges enabling them to divide in unison towards the lumen

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6
Q

Spermatogenesis: Why do some spermatogonia not have intercellular bridges?

A

to replenish the pool of germ cells so continuous sperm production can occur

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7
Q

Spermatogenesis: What do Primary spermatocytes undergo to give secondary spermatocytes?
- What about secondary spermatocytes to give spermatids?

A

meiosis 1

meiosis 2

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8
Q

Spermatogenesis: State the 4 phases of differentiation

A

Golgi phase
cap phase
acrosomal phase
maturation phase

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9
Q

Spermatogenesis: What happens in the Golgi phase? 6

A

vesicles inside Golgi apparatus fuse to form proacrosomal granules
these granules fuse to form an acromic vesicle
the acrostic vesicle contains an acrostic granule
centrioles move the the base of the nucleus
the proximal centriole anchors the tail to the nucleus
the distal centriole forms the central flagellum

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10
Q

Spermatogenesis: What happens in the Cap shape? 3

A

the acrostic vesicle forms a cap structure over the top of the nucleus
the Golgi apparatus migrate and disappear
the primitive flagellum forms

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11
Q

Spermatogenesis: What happens in the Acrosomal phase?

A

the acrosome spreads and the nucleus elongates
manchette tubules are formed
the neck and annulus are formed

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12
Q

Spermatogenesis: What happens during the Maturation phase?

A

the manchette form the post nuclear cap
the mitochondria form in a spiral assembly in the middle piece

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13
Q

Spermatogenesis:
- What is contained within there acrosome?
- What 4 sections is the tail composed of?

A

hydrolytic enzymes for penetrating the zona pellucida

capitum
middle piece
principle piece
terminal piece

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14
Q

Spermatogenesis: What is ‘one cycle of the seminiferous epithelium’?
- How long is it?

A

progression through a complete series of stages at one location along a seminiferous tubule

it varies between species

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15
Q

Spermatogenesis: How many different sections are there on the seminiferous epithelium?
- Do the intercellular bridges extend between sections?

A

8

no

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16
Q

Spermatogenesis: How many cycles does it take for spermiation to occur?

A

4.5 cycles

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17
Q

Spermatogenesis: How long does it take primary spermatocytes to become secondary spermatocytes?
- How long does it take secondary spermatocytes to become spermatids?

A

21 days

1.7 days

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18
Q

Spermatogenesis: What is a Spermatogenic wave?

A

the differences at any given instant in time along the seminiferous tubule

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19
Q

Spermatogenesis: What is spermatogenesis dependent on? 3

A

GnRH secretion from the hypothalamus
FSH and LH secretion from the anterior pituitary
Testosterone and Oestradiol secretion from the gonad

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20
Q

Spermatogenesis: What does LH do when released from the anterior pituitary?

A

it binds to receipts on Leydig cells
this stimulates Leydig cells to secrete testosterone

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21
Q

Spermatogenesis: What does FSH do when released? 4

A

it binds to receptors on Sertoli cells
this enables them to function
this stimulates Sertoli cells to convert testosterone to oestradiol
and they secrete inhibin

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22
Q

Spermatogenesis: After Leydig cells secrete testosterone, what happens to the testosterone?

A

some of the testosterone is converted in oestradiol by Sertoli cells under the influence of FSH
oestradiol has a negative feedback effect on the hypothalamus
some of the testosterone diffused into the seminiferous cords
it is converted into dihydrotestosterone
dihydrotestosterone has a negative feedback effect on the hypothalamus

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23
Q

Spermatogenesis: Which part of the Sperm contain the mitochondria needed to generate ATP for the flagellum to propel the sperm?

A

the middle piece

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24
Q

Spermatogenesis: Once the spermatids have differentiated into Spermatozoa, what happens?
- When in the head of the epididymis, explain whether or not they can fertilise an oocyte

A

spermatozoa are released into the seminiferous tubule lumen
they enter rete tubules
they travel through efferent ducts into the head of the epididymis

no they cannot as they are not fully mature or motile

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25
Spermatogenesis: how long does it take for sperm to progress through the head, body and tail of the epididymis to become fully mature? - What is happening to the sperm as they move further down the tubule? 2
2 weeks they become more mature and motile the cytoplasmic droplet is moving down the sperm
26
Spermatogenesis: - Is the time taken to travel through the head and body variable? - what about to go through the tail and why?
no it is fixed yes because the tail has limited storage capacity
27
What is the function of seminal plasma? 6
it provides a transport medium for sperm it contains fructose which provides nutritional support for sperm it has a buffering capacity to protect sperm against the acidic conditions in the vagina it contains antioxidants to get rid of free radicals formed by sperm during ATP production it contains proteins which bind to the sperms head prostaglandins produced from the prostate gland causes the muscles in the female tract to contract and helps sperm progress
28
Semen: Where is semen deposited in the cow? - How much is deposited? - how long is copulation?
in the cranial aspect of the vagina 1ml 1-3 seconds
29
Semen: Where is semen deposited in sheep? - How much is deposited? - how long is copulation?
in the vagina 8ml 1-2 seconds
30
Semen: Where is semen deposited in the sow? - How much is deposited? - how long is copulation?
in the cervix and leaks into uterus 250ml 5-20 minutes
31
Semen: Where is semen deposited in Camelids? - How much is deposited? - how long is copulation?
in the vagina and leaks into cervix and uterus 8ml 5-20 minutes
32
Semen: Where is semen deposited in the Horse? - How much is deposited? - how long is copulation?
in the cranial vagina and leaks into the cervix and vagina 100ml 60 seconds
33
Semen: Where is semen deposited in the dog? - How much is deposited? - how long is copulation?
in the vagina 3ml 5-45 minutes
34
Post Copulation: For species where sperm are not deposited in the cervix, the sperm need to cross the cervix to enter the uterus. - Which species form a vaginal plug? - What is it made from? - What is its purpose? 2
rodents coagulated semen to prevent further mating to prevent retrograde transport of sperm
35
Post Copulation: Why must fertilisation happen quickly after copulation?
because the sperm will be recognised as foreign by the immune system and destroyed
36
Post Copulation: when are sperm activated? - Describe how they move 3 - what assists the transport of sperm?
after ejaculation they swim in a straight line their head rotates their flagellum moves in a wave motion contractions of the female tract
37
Post Copulation: State some tail abnormalities in sperm that would result in abnormal movement and lead to lower fertility 4
coiled tail folded tail detached head double mid piece
38
Post Copulation: Cervix - Via which pathway do sperm cross the cervix? - Describe the journey of sperm across the cervix 2 - What is the purpose of the barrier this mucus presents? 2
the privilege pathway the cervix secretes sulphomucin which is a highly viscous mucus secretion which the sperm cannot swim through the cervix also secretes sialomucin which is a low viscosity mucus secretion which the sperm can swim through to slow down the sperm to ensure there is a sperm reservoir to remove any non-motile sperm
39
Post Copulation: Describe sperm transport through the uterus - why is this the case? 3
it is rapid due to elevated tone and motility of the muscular layers of the female tract this is stimulated by oestradiol and oxytocin at oestrus it is also stimulated by prostaglandins in the seminal fluid
40
Post Copulation: At the tip of the uterine horn, the sperm must cross which junction? - Describe the lumen for the uterine tube - What does passage through this tube require from sperm?
the uterine-tubal junction narrow lumen it requires vigorous sperm motility
41
Post Copulation: Uterine Tube (oviduct) - Describe what happens to sperm immediately after entering the uterine tube - what is the purpose of this? - When do the sperm become motile again? - What happens next?
sperm binds to epithelial cells via seminal proteins to render them immotile and prolong their lifespan around ovulation they swim towards the ampulla region
42
What does ovulation induce in the oocyte?
completion of meiosis 1
43
Capacitation: Where does this usually occur? - what happens? 5
in the uterine tube decapacitation factors are removes calcium and bicarbonate ions move into the sperm this causes membrane destabilisation the sperm detach from the oviduct epithelium and become hyperactive they begin swimming towards the ampulla
44
Post Copulation: After capacitation, how has the movement of the flagellum changed?
it is moving asymmetrically at a high amplitude
45
Sperm reaches Oocyte: What has to happen prior to the acrosome reaction once the sperm reaches the oocyte?
there must be specific alignment of the sperm and oocyte
46
Sperm reaches Oocyte: Describe the composition of the Zona pellucida 3
it consists of 3 layers of glycoproteins layer 3 expresses ZP3 receptors this is the specific binding region
47
Acrosome Reaction: What is it initiated by? - Describe what happens 7
the sperm binding to the zona pellucida the acrosome releases hydrolytic enzymes these digest the zona pellucida in a localised region the sperm head penetrates the zona pellucida this requires hyperactivity of the flagellum the plasma membrane of the sperm fuses with the plasma membrane of the oocyte the sperm nucleus enters the oocyte the nuclei fuse
48
What does the action of sperm binding to the oocyte trigger in the oocyte?
an influx of calcium ions which indices completion of meiosis 2
49
Describe the events of the cortical reaction 3 - what is the purpose of this reaction?
the oocyte contains cortical granules near its membrane their contents is released when the sperm binds to the oocyte this causes the zona pellucida to harden to destroy sperm receptors and prevent polyspermy
50
Ovulation: What is a spontaneous ovulator? - What is an Induced ovulator?
where ovulation is independent of mating where ovulation is stimulated by mating
51
Ovulation: Describe what happens at ovulation 4
the follicular wall bursts the oocyte is released the oocyte is carried with follicular fluid into the peritoneal cavity the oocyte is captured by fimbria of the infundibulum
52
Define Fertilisation period
the period of time when oocytes are available to be fertilised by sperm
53
Define fertile period
the period of time when mating could result in pregnancy
54
Ovulation: When does a dogs oocyte get ovulated? - How is this different from other species? - What does this mean for the dog?
during metaphase of meiosis 1 ovulation induces completion of meiosis 1 in other species completion of meiosis 2 and the formation of a second polar body occurs after fertilisation
55
State the fertilisation period for the Dog - State their fertile period
2-5 days after ovulation 5 days before and 5 days after ovulation
56
What is embryonic diapause? - Which species does this occur in?
temporary arrest of embryo development characterised by a delayed implantation in the uterus marsupials
57
What is it called, before fusion of the nuclei, when the 2 pro-nuclei can both be seen in the cell? - what is it called when the 2 nuclei fuse?
an ootid syngamy
58
Embryo Development: After the nuclei fuse - - what happens? - what name can be given to these cells?
the zygote undergoes cleavage divisions blastomeres
59
Embryo Development: What is different about cleavage divisions compared to other mitotic divisions? - Why can blastomeres be thought of as 'Totipotent' until the Morula stage? - After cleavage divisions have made 16 blastomeres, what is this 16 cell embryo called?
there is no cytoplasm synthesis so blastomere volume decreases because each blastomere has the ability to form all cells necessary for normal embryo devleopment a morula
60
Embryo Development: Describe the inner structure of the morula 3
the outer cells within the morula are more squashed than the inner cells the outer cells form tight junctions the inner cells form gap junctions
61
Embryo Development: What do the Outermost cells of the morula do? - What is the consequence of this? 3
they pump sodium ions into the morula this decreases the water potential inside the morula so water diffuses into the morula by osmosis fluid accumulates inside the morula
62
Embryo Development: What can be call the Morula once water influx has formed a distinct cavity inside?
a blastocyst
63
Blastocyst: What do the outer cells become? - What do the inner cells become?
the trophoblast the inner cell mass
64
Blastocyst: Why is pressure building inside the blastocyst? 3
because cells are still undergoing mitotic divisions and fluid is still diffusing into the cell and the hard zona pellucida provides a fixed volume
65
Blastocyst: The pressure inside the Blastocyst is high. - what do trophoblast cells do? - What consequence does this have?
they secrete proteolytic enzymes this weakens the zona pellucida it splits the blastocyst emerges
66
Conceptus Progression: After fertilisation, is the embryo continually progressing towards the uterus?
yes
67
Conceptus Progression: Describe the progression of the conceptus in the sow and rabbit
slow and continuous
68
Conceptus Progression: Describe the progression in the cow, ewe and human - What does this mean? - How does this occur? - Does this occur for non-fertilised oocytes too?
discontinuous progression there is a prolonged stay in the uterine tube anti peristaltic contractions maintain the conceptus in the uterine tube for 2-3 days then stronger peristaltic contractions progress the conceptus forward yes
69
Conceptus Progression: Describe the progression of the conceptus in the mare - What does this mean? - How does this work? 2
fertilised progression only fertilised embryos pass into the uterus the embryo secretes prostaglandins e and f these promote embryo migration through the uterine tube and into the uterus
70
After Blastocyst Hatching: what do endometrial glands do?
it secretes histotroph which provides nutritional support before the placenta is established
71
Membrane Formation: - What does the inner cell mass give rise to? - what will each layer form?
the epiblast and hypoblast the epiblast will form amniotic ectoderm so the amnion the hypoblast will form primitive endoderm so the yolk sac
72
Membrane Formation: What does the hypoblast do?
it grows down and forms a cavity within the trophoblast called the yolk sac
73
Membrane Formation: Extraembryonic mesoderm appears - What does it do? 3
it grows ventrally forming a sac surrounding the yolk sac it grows dorsally forming amniotic folds the mesoderm fuses with the trophoblast where they meet forming the chorion
74
Membrane Formation: - What is the Allantois? - Describe its growth 2
an out pouching of the hindgut it grows as the yolk sac regresses it fuses with the chorion where is meets forming the chorioallantoic membrane
75
Membrane Formation: Gastrulation - Where does it begin? - What happens
at the caudal end of the embryo where the node arises cells from the epiblast migrate through the primitive streak they differentiate into the ectoderm, mesoderm and endoderm
76
Establishing Pregnancy: In the absence of an Embryo, what happens? (excluding the bitch)
luteolysis is induced by prostaglandin f2 alpha this causes progesterone to decline the dam will return to oestrus within a few days
77
Establishing Pregnancy: Describe what happens in Ruminants if no embryo is present 5
oxytocin receptors are absent for most of the luteal phase oxytocin receptors eventually appear in the endometrium oxytocin produced from the corpus luteum binds to oxytocin receptors this stimulates prostaglandin release prostaglandin induces luteolysis
78
Establishing Pregnancy: Knowing how luteolysis is induced, what type of compound could delay luteolysis?
an oxytocin receptor antagonist
79
Establishing Pregnancy: Are oxytocin receptors present in the luminal epithelium throughout dioestrus? 2
no they are suppressed by progesterone they appear by an unknown mechanism jut before luteolysis
80
Establishing Pregnancy: After Oxytocin binds to the Oxytocin receptor in the endometrium, what happens? - In ruminants, how does this prostaglandin act directly on the ovary?
it stimulates pulsatile release of prostaglandin f2 alpha from the endometrium due to a counter current system
81
Establishing Pregnancy: Which hormone increases during luteolysis? - What effect does this have on luteolysis?
oestradiol it increases oxytocin receptor transmission so speeds up luteolysis
82
Establishing Pregnancy: Describe the positive feedback loop during Luteolysis 2
endometrial prostaglandin stimulates the corpus luteum to release more oxytocin oxytocin stimulate the production of more endometrial prostaglandin
83
Maternal Recognition: Why is maternal recognition of pregnancy required?
to avoid luteolysis and sustain the pregnancy
84
Maternal Recognition: What is the function of Prostaglandin in sustaining a pregnancy? 3
it maintains uterine gland secretion of histotroph it suppresses myometrial contractions and luteolysis it suppresses GnRH secretions to reduce follicular maturation to suppress ovulation
85
Maternal Recognition: What is the Embryonic Signal In Ruminants? - Describe how this is produced 3 - How long is it expressed for?
Interferon Tau the blastocyst starts expressing this protein during trophoblast elongation it is expressed by trophectoderm cells its expression is stimulated by growth factors secreted by the uterus between days 12-24 of pregnancy
86
Maternal Recognition: Do all embryos secrete the same amount? - Where does it remain after secretion? - What is a lack of Interferon Tau associated with?
no secretion is relative to embryo size in the lumen of the uterus where it exerts its action embryo mortality
87
Maternal Recognition: Ruminants and Interferon Tau - Where does IFT exert its action? - What does it do? 3
on the endometrium it suppresses oxytocin receptor expression it stimulates protein synthesis critical for embryo growth it has antiviral activity
88
Maternal Recognition: What is the conceptus signal in Pigs? - When is this secreted? - Is it detectable in plasma? - What does it do?
oestradiol just before implantation slightly it redirects the flow of prostaglandin away from the uterine vein
89
Maternal Recognition: What is the conceptus signal in horses? - What do we know? 2
it is unknown the embryo suppresses oxytocin receptors no blastocyst interferons are produced
90
Maternal Recognition: What is the conceptus signal in primates? - What is different about the luteolytic mechanism in primates? - Hence, what does the conceptus signal do?
chorionic gonadotrophin prostaglandin f2 alpha is secreted by the ovary it acts on LH receptors on the corpus luteum to suppress prostaglandin release form the ovary
91
Maternal Recognition: What is the Conceptus signal in dogs? - What does this mean?
there is no maternal recognition of pregnancy the non-pregnant female will enter pseudopregnancy
92
Timing of Maternal recognition of Pregnancy: - For which animals does it occur before implantation? - State the day it occurs for each
cow - day 16 ewe - day 13 sow - day 12
93
Timing of Maternal recognition of Pregnancy: - For which animals does it occur in Mid gestation?
rabbits and rodents
94
Timing of Maternal recognition of Pregnancy: - Which species dont have maternal recognition of pregnancy?
dogs and ferrets
95
Timing of Maternal recognition of Pregnancy: - When does Equine maternal recognition occur?
day 14
96
State the Gestation Lengths for the following species: - Dog - Cat - sheep - cow - horse - pig - rabbit
63-65 days 63 days 150 days 285 days 330 days 114 days 31 days

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