Lecture 3 - Gametogenesis Flashcards
1
Q
gametes
A
- ova
- spermatozoa
2
Q
germ cells
A
germ plasm
3
Q
somatic cells
A
somatoplasm
4
Q
two types of gametogenesis
A
- oogenesis
- spermatogenesis
5
Q
Phases of Gametogenesis
A
- Origin of germ cells and migration to gonads
- multiplication of germ cells via mitosis
- reduction of no. of chromosomes by 1/2 via meiosis
- final stages of maturation and differentiation of gametes into spermatozoa or ova
6
Q
maturation of spermatids to spermatozoa
A
spermiogenesis
7
Q
recognized early in life as regions in the vegetal pole cytoplasm of the zygote or as specific cells during cleavage stage
A
germplasm (frogs and invertebrates)
8
Q
can be traced through cleavage and into the endodermal floor of the primitive gut
A
germ-cell lineage
9
Q
origin of germ cells in birds, reptiles, and mammals
A
primordial germ cells (PGC) in epiblast of early embryo
10
Q
origin of germ cells in birds
A
germinal crescent locaated beyond the head region of embryo
11
Q
origin of germ cells in mammals
A
posterior wall of yolk sac near region of allantois
12
Q
origin of germ cells in urodele amphibians
A
through influence of venral endodermal yolk mass different from Anurans
13
Q
recognizable due to large size and clear cytoplasm
A
primordial germ cell (PGC)
14
Q
histochemical characteristics of primordial germ cell
A
- high alkaline phosphatase activity (mammals)
- high glycogen content (birds)
- monoclonal Ab’s (birds and mammals)
15
Q
clones of your body’s antibodies that are made in a laboratory, meant to stimulate your immune system
A
Monoclonal antibodies
16
Q
in vertebrates, where do PGC migrate to
A
gonads
17
Q
Two principal mechanisms on how PGC migrate to gonads
A
- pass through walls of blood vessels and enter circulation. Penetrate blood vessels and settle down in gonads (birds and reptiles)
- reach gonads by migration around wall of posterior gut and then through dorsal mesentery
18
Q
extracellular matrix molecules that guide the PGC to gonads within the mesentery
A
- laminin
- fibronectin
19
Q
migration of primordial germ cell to gonads in mouse
A
- PGCs established in epiblast migrate to definitive endoderm
- migrate through gut and, dorsally, into genital ridges
- enters genital ridges around embryonic day 11
20
Q
what happens to PGC once it settled in the gonads
A
enter proliferative phase; increase number via mitosis
21
Q
active germ cells mitotically in females
A
oogonia
22
Q
active germ cells mitotically in males
A
spermatogonia
23
Q
in female humans, when does intense mitotic activity happen
A
between 2nd-5th mos of pregnancy
24
Q
no. of initial oogonia
A
7 million
25
why do oogonia number fall sharply
atresia (natural degeneration)
26
7th month of pregnancy
oogonia entered prophase of 1st meiotic division
27
oogonia after 1st meiotic division
primary oocytes
28
oogonia of nonmammalian vertebrates
capable of dividing throughout reproductive cycle
29
mitosis of germ cells in rodents
continues in gonad of early embryo; ceases during later days of pregnancy; resume after birth
30
mitosis of germ cells in male humans
beggining at puberty; produces spermatocytes that enter meiosis; continues as long as male is capable of reproduction
31
reproductive role of human male
produce sperm and deliver them to vagina of female
32
deposists semen in the vagina during sexual intercourse
penis
33
produce fluid called semen for carrying sperm to te penis
accessory glands
34
produce sperm and male sex hormone, testosterone
testes
35
seminiferous tubules
36
sperm structures
1. head
2. midpiece
3. tail
37
parts of the female reproductive system
1. ovaries
2. uterine tubes/oviduct
3. vagina
4. external genitalia
38
produce milk for newborn baby
mammary glands
39
branched vaginas
marsupials
40
uterus has body and horn
dogs, cats, rabbit
41
Human Female Uterus
1. uterine tube
2. round ligament
3. perimetrium
4. myometrium
5. endometrium
6. internal os
7. cervical canal
8. external os
9. fornix
10. cervix
11. vagina
42
propels egg cells
cilia
43
production of gametes
gametogenesis
44
- formation of sperm
- continuou and prolific
spermatogenesis
45
how long do each sperm takes to develop
7 weeks
46
different stages of sperm
1. primordial germ cell
2. spermatogonial stem cell
3. spermatogonium
4. primary spermatocyte
5. secondary spermatocyte
6. early spermatid
7. sperm cell
47
under mitotic divisions
1. spermatogonial stem cell
2. spermatogonium
3. primary spermatocyte
48
after meiosis I (male)
secondary spermatocyte
49
after meiosis II (male)
early spermatid
50
after differentiation (male)
sperm cell
51
where do germ cells progress toward as they mature
lumen of seminiferous tubule
52
enzyme in sperm cell
acrosome
53
how many seminiferous tubules do testes contain
1-3 coiled seminiferous tubules
54
how many sperms does one normal human ejaculate contain
several hundred million sperm
55
- development of a mature egg
- prolonged process
oogenesis
56
under mitotic divisions (female)
- oogonium
- primary oocyte
57
when is the primary oocyte arrested
prophase of meiosis I
58
under meiosis (female)
- secondary oocyte
- fertilized egg
59
when is the secondary oocyte arrested
metaphase of meiosis II
60
when is meiosis II competed
after sperm entry
61
formed after the rupture of follicle
corpus luteum
62
when does the completion of meiosis I and onset of meiosis II happen
start at puberty
63
stages of oocyte
in embryo
1. primary oocyte within follicle
2. growing follicle
start at puberty
3. mature follicle
4. ruptured follicle (ovulated secondary oocyte)
5. corpus luteum
6. degenerating corpus luteum
64
spermatogenesis:
after meiosis I and II
4 functional spermatozoa
65
spermatogenesis:
start of development
- dont begin until puberty
- continues throughout life
66
spermatogenesis:
meiotic arrest
- no prolonged meiotic arrest
- entire process completed in more than 2 months
67
spermatogenesis:
size
mature sperms smaller than spermatogonia
68
spermatogenesis:
nutrition
contribution by Sertoli cells
69
spermatogenesis:
energy source
- rely on seminal fluid
- little or no RNA synthesis occurs
70
oogenesis:
after meiosis I and II
- ooctye + 1st polar body
- oocyte + 2nd polar body
71
oogenesis:
start of development
meiosis I begins in embryo and not completed until onset of puberty
72
oogenesis:
meiotic arrest
- prolonged arrest in prophase I diploete stage for 40 yrs
- 2nd arrest occurs in metaphase II
73
oogenesis:
size
mature ova larger than oogonia
74
oogenesis:
nutrition
eggs take up large quantities of materials produced by liver
75
oogenesis:
energy source
- stores both energy sources and precursos of proteins and nucleic acids
- produces and stores up much RNA
76
coordinates human reproduction
hormones from hypothalamus, anterior pituitary, and gonads
77
secreted by the hypothalamus that directs the release of FSH and LH from the anterior pituitary
Gonadotrpin-releasing hormone (GnRH)
78
what does GnRH direct the release of
- FSH
- LH
79
FSH
follicle-stimulating hormone
80
LH
luteinizing hormone
81
where is FSH and Lh from
anterior pituitary
82
what are the main sex hormones
steroid hormones
83
main androgen
testosterone
84
what does estrogen consist mainly of
- estradiol
- progesterone
85
other function of sex horones asside from gamete production
- sexual behavior
- development of primary and secondary sex characteristics
86
FSH effect
Sertoli cells release inhibin
87
LH effect
Leydig cells secrete testosterone
88
negative feedback of inhibin
anterior pituitary
89
negative feedback of testosterone
- anterior pituitary
- hypothalamus
90
nourish developing sperm
Sertoli cells
91
secrete testosterone and other androgens which promote spermatogenesis
Leydig cells
92
what does testosterone regulate
production of GnRH, FSH, and LH
93
reduces FSH secretion fro the atnerior pituitary
Inhibin (from Sertoli cells)
94
where is FSH produced from
pituitary gland
95
- aids sperm maturation
- increases testosterone production
FSH (follicle-stimulating hormone)
96
controls pituitary secretion
GnRH (gonadotropin-releasing hormone)
97
source of GnRH
hypothalamus
98
inhibits FSH secretion n
inhibin
99
source of inhibin
sustentacular cells
100
stimulates testosterone secretion
LH or ICSH
101
ICSH
interstitial cell-stimulating hormone
102
source of LH or ICSH
pituitary gland
103
- increases sperm production
- stimulates development of male primary and secondary sexual characteristics
- inhibits LH secretion
testosterone
104
source of testosteron
interstitial cells in testes
105
shedding of endometrium
menstruation
106
changes in the uterus
define menstrual or uterine cycle
107
changes in ovaries
define ovarian cycle
108
where is the pattern of hormone secretion intricately related to
cyclical release of secondary oocyte from the ovary
109
- stimulates thickening of uternine wall, maturation of oocyte, and development of female sexual characteristics
- inhibits FSH secretion
- increases LH secretion
estrogen (estradiol)
110
source of estrogen in female
ovarian follicle, corpus luteum
111
- causes immature oocyte and follicle to develop
- increases estrogen secretion
- stimulates new gamete formation and development of uterine wall after menstruation
FSH (follicle-stimulating hormone)
112
controls pituitary secretion
GnRH (gonadotrpin-releasing horomone)
113
inhibits secretion of FSH from the anterior pituitary gland
inhibin
114
source of inhibin in female
ovaries
115
- prevents corpus luteum from disintegrating
- stimulates corpus luteum to secrete estrgen and progesterone
hCG (human chorionic gonadotropin)
116
source of hCG
embryonic membranes and placenta
117
- stimulates further development of oocyte and follicle
- stimulates ovulation
- increases progesteron secretion
- aids in development of corpus luteum
LH (luteinizing hormone)
118
soruce of LH
pituitary gland
119
stimulates uterine contraction during labor and milk release during nursing
oxytocin
120
source of oxytocin
pituitary gland
121
promotes milk secretion by mammary glands after childbirth
prolactin
122
source of prolactin
pituitary gland
123
stimulates thickening of uterine wall
progesterone
124
source of progesteron
corpus luteum
125
increases flexibility of pubic symphysis during pregnancy and helps dilate uterine cervix during labor and delivery
relaxin
126
source of relaxin
placenta and ovaries
127
characterize the follicular phase of teh ovarian cycle
- follicle growth
- increase in estradiol
128
thickening of the endometrium during the poliferative phase
coordinates with the follicular phase
129
secretion of nutrients during the secretory phase
coordinates with luteal phase
130
shedding of the endometrium furing teh menstural flow phase
coordinates with the growth of new ovarian follicles
131
- follicle matures in the ovary
- menstruation
- endometrium rebuilds
follicular phase (1-5 days)
132
ovary releases secondary oocyte
ovulation (6-24 days)
133
- corpus luteum forms
- endometrium thickens and becomes glandular
luteal phase (15-28 days)
134
pregnancy outside the uterus
ectopic pregnancy
135
swelling of endometrium
endometriosis
136
cessation of ovulation and menstruation
menopause
137
menopause happens after about how many cycles
500 cycles
138
how might menopause evolved
allow a mother to provide better care for her children and grandchildren
139
- endometrium is reabsorbed by the uterus
- sexual receptivity is limited to a "heat" period
- length and frequency vary
estrous cycle
140
heat period
estrus
