Embryology week 14 Flashcards
1
Q
What is the 2 periods human development is divided into
A
- Prenatal (before birth)
-Postnatal(after birth)
2
Q
The development of a human from fertilization of an oocyte to birth is divided into what types of periods
A
- Embryonic and fatal
3
Q
Explain the embryonic period:
-When it occurs
-And what it contains
A
- During week 3 -8
-Contains rapid visible development
4
Q
Explain what happens in the fetal period
A
-Differentiation,Organ growth, and accelerated body growth
5
Q
What does stage 1 of embryonic development begin as
A
- Fertilization
6
Q
When does embryonic development end
A
- At stage 23 , which is day 56
7
Q
When does critical development occur
A
- During the first trimester(13 weeks)
8
Q
What does the Prenatal period incude
A
Embryonic period
Fetal period
9
Q
What does the postnatal period contain
A
- Infancy, Childhood, Puberty and adulthood
10
Q
Explain infancy and what happens during infancy
A
- Body grows rapidly, weight triples, 6-8 teeth emerge by age 1
11
Q
What is an infant age 1 month or younger
A
neonate
12
Q
Explain when Childhood occurs
- What it contains
A
- Between infancy and puberty
-Activebone ossification , apperance of primary teeth - Growth slows
13
Q
When does puberty begin for males and females
A
- Around age 8 for females and age 9 males
14
Q
What does puberty mark
A
- Functional reproductive capability
15
Q
In adulthood when is full growth and maturity achieved
A
Ages 18-21
16
Q
What is the definition of gametogenesis
A
- It is the formation and development of specialised reproductive cells (gametes)
from biopotential precursor cells
17
Q
Name the types of gametogenesis and what it is
A
- Spermatogenesis( male gamete formation)
-Oogenesis(female gamete formation)
18
Q
What is the definition of Meiosis
A
-Cell division involving 2 meiotic divisions
19
Q
What is the purpose of meiosis
A
Converts diploid germ cells into haploid gametes
20
Q
Explain what happens in the first meiotic division to the :
1.Chromosomes
2.Homologous chromosomes in prophase and anaphase
3.What It results in
A
1.The chromosome number is reduced from from (diploid )46 to 23 (haploid)
2. Homologous chromosomes pair in prophase and seperate in anaphase
2. Haploid cells
21
Q
What does the second meiotic division occur without
A
DNA replication
22
Q
What happens in second Meiotic division
A
Double -Chromatid chromosome divide into single-chromatid chromosomes
23
Q
What does the Second Meiotic division start with
A
Haploid cells
24
Q
What is the purpose of spermatogenesis
A
- Transformation of spermatogonia into mature sperm
25
When does spermatogenesis begin and occur
- At puberty
- Occurs in the seminiferous tubules of the testes
26
Explain the stages of spermatogenesis
- Spermatogonia undergo mitotic divison
-Primary spermatocytes undergo first meiotic divison, producing secondary spermatocytes
- Secondary spermatocytes undergo second meiotic divison , forming 4 haploid spermatids
27
What is spermiogenesis
-How long does it take
When spermatids mature into functional sperm and takes 2 months
28
What is the role of sertoli cells
They support nurture and regulate spermatogenesis
29
Where is sperm stored,matured and gains motility
- In the epididymis
30
What does the sperm head contain
- Nucleus and acrosomes (enzymes for digestion)
31
What is the function of the tail of the sperm
-Enables movement , powered by mitochondria
32
What is Oogenesis
- Where oogonia transforms into mature ooctyes
33
When does oogonia become occytes
Before birth
34
When does oogenesis end/ continue to
- Until menopause
35
Explain what happens in Prenatal maturation of Oocytes:
starting with
-Oogonia
-Oogonia proliferates(increase in number) via mitosis during early fetal life
-They then enlarge and become primary occytes,surrounded by follicular cells, forming Primordial follicles
36
How are primordial follicles formed during prenatal maturation of occytes
- When the primary oocytes are surrounded by follicular cells, forming primordial follicles
37
When does postnatal maturation of Oocytes occur
- At puberty
38
Explain what happens in postnatal maturation after primary oocyte completes their first meiotic division
- Produce:
- Secondary oocyte
-First polar body
39
Explain what happens to secondary oocyte after formation in the postnatal maturation of oocytes
- Starts the second meiotic division but stops at metaphase
- It is fertilized by sperm and completes meiois to produce:
- Fertilized oocyte
-Second polar body
40
Describe the structure of the uterus
- Thick-walled, pear shaped muscular organ
41
Name the parts of the uterus
- Body
-Cervix
42
What does the body of the uterus contain
- Fundus and the isthmus
43
What does the cervix part of the uterus contain
- Internal os(opening)
-External os(opening)
44
Where do the uterine tubes extened from
Uterine horns to the peritoneal cavity
45
Name the 4 parts the Uterine tubes are divided into
- Infundibulum
-Ampulla
-Isthmus
-Uterine part
46
What is the function of uterine tubes
- Transport Oocytes from ovaries
-Carry sperm to fertilization sites
47
Explain the structure of Ovaries
- Almond-shaped reproductive glands
48
What is the function of the ovaries
- Produce oocytes
-Secret oestrogen and progesterone
49
Explain how Oocytes are transported starting with secondary oocytes
- The secondary oocyte is expelled from the ovarian follicle
-The fimbriae sweeps the oocyte into the infundibulum
-Then the oocyte travels to the ampulla via the peristalis
50
Explain how sperm is transported
- From the epididymis to the urethra by peristalis
51
Where is sperm deposited?
where do they pass through
Near the external os
Pass through the cervical canal using tail movements
52
What happens to the sperm that dont reach the fertilisation site
- Absorbed or degenerated
53
When can freshly ejaculated sperm fertilize an oocyte
- They must undergo capcitation
54
How long does capacitation take
7 hrs
55
What happens in capacitation
- It removes the glyvoprotein coat
-Increases sperm activity
-Alters the membrane components
56
Where does capacitation take place
- Uterus/uterine tubes
57
When does the acrosome reaction take place in relation to sperm maturation
After capacitation
58
What happens in the acrosome reaction
-What does it require
-Sperm binds to ZP3 glycoprotein on the zona pellucida
- Calcium ions,prostaglandins and progesterone
59
What is the function of Hyaluronidas and acrosin enzymes during sperm maturation
- Helps the sperm to penetrate the egg
60
What is capacitation and acrosome reaction regulated by
Tyrosine kinase
61
Name and Explain the first step of fertilisation with enzymes included
Passage of the sperm through the Cornoa Radiata
- Hyaluronidase enzymes ( from sperm acrosome) helps to disperse follicular cells
-
62
Name and explain the second step of Fertilization
- Penetration of the Zona pellucida
- Acrosomal enzymes break down the zona pellucida, allowing sper, entry
63
Explain the 3rd step of fertilization after sperm has entered the zona pellucida
- After sperm enters the zona pellucida, the zona pellucida undegoes changes to become impermeable to other sperms
-Lysosomal enzymes from cortical granules modify the zona and oocyte membrane
64
Explain the 4 step of fertilization (fusion)
- The head and tail of the sperm enter the oocyte, while the sperms plasma membrane and mitochondria remain outside
65
Expain what happens after the fusion of the Oocyte and sperm membrane ( Completion of Oocytes second meiosis division)
The oocyte completes meiosis 2, forming the female pro nucleus and second polar body
66
When and how is the male pronucles formed during fertilization
- After the oocyte completes meiosis 2
- When the sperm nucleus enlarges, forming the male pronucls
67
During fertilization what does the fusion of the male and female pro nuclei form
- Diploid zygote (46 chromosomes)
68
What is cleavage of zygote
It is a series of mitotic divisions that increase the number of cells - blastomeres without increasing the overall size
69
When does Clevage of zygote begin
30 hours after fertilization
70
When does clevage of zygote occcur
When the zygote moves through the uterine tubes toward the uterus
71
Name the 2 stages in the clevage of a zygote
- Compaction
- Morula Stage
72
Explain what happens in the compaction stage in cleavge of zygotes
+ what it is mediated by
-Blastomeres chnage shape and tighlty align into a compact ball
- Mediated by cell surface adhesion glycoproteins
73
What is the compaction stage necessary for forming
- The embryoblast of the blastocyst
74
What is morula in the cleavge of a zygote
- Developing human
75
When does a morula form in the Cleavage of a zygote and how many days after fertilization does it form
- when there are 12-32 blastomeres
- 3 days after fertilization
76
In morula stage of clevage of zygotes what does the internal cells and outer cells become
internal cells: embryoblasts
outer cells: trophoblast
77
Explain the first step of Blastocyst formation
+ What day does this occur
-The morula enters the uterus, and a blastocystic cavity forms.
-Fluid passes through the zona pellucida, separating blastomeres into:
Trophoblast:
Embryoblast
- 4 days after fertilization
78
What happens in the second step of blastocyst development on day 6
- The embryoblasts projects into the blastocystic cavity
- The trophoblast forms the blastocyst wall
- The zone pellucida degenerates
79
Explain the 3 step of blastocyst formation dat 6-7
- The blastocyst attches to the endometrial epithelium
- The trophoblast proliferates and differntiates into
- Cytotrophoblast
-Syncytiotophoblasts
80
What happens by the end of the 1 week during blastocyst formatioj
- The blastocyst
is implanted in the compact layer
