module 4- male reproduction, sex determination, mating Flashcards
1
Q
sexual dimorphism & example
A
distinguishes members of same species by sex
- size
2
Q
T or F: sexual dimorphic traits are low in numbers
A
T
3
Q
sex differences & example
A
differences in average of a phenotype between males & females
- height
4
Q
T or F: females & males have same hormones but produced in diff amounts
A
T
5
Q
sex of an animal
A
the ability to produce a particular type of gamete along with any associated phenotypic traits
6
Q
intersex individuals
A
animals born with varying presentations of male & female genitalia
7
Q
example of intersex animal
A
honeycreeper
8
Q
sex determination
A
process of development of ovaries or testes from embryonic gonad
9
Q
why can you have sex reversal?
A
b/c the integration of community cell fates are not set in stone
10
Q
GSD vs ESD
A
GSD- genetic sex determination, depends on sex chromosomes, most common way
ESD-environmental sex determination, no sex chromosomes, depends on external factors
11
Q
mammals/frogs, birds/amphibians & insects genotype for males vs females
A
mammals/frogs: XY = male
amphibians/birds: ZZ male
insects: XO = male
12
Q
what is the oldest known animal for sex chromosomes
A
octopus (XX=male)
13
Q
1st, 2nd & 3rd trimester major events
A
1) fertilization
2) sex determination
3) testicular descent
14
Q
primordial germ cells
A
stem cells that are capable of becoming egg or sperm
15
Q
T or F: yolk sac is for blood cell development
A
T
16
Q
what occurs when yolk sac is abolished?
A
primordial germ cells move back into the embyro
17
Q
how do primordial germ cells move?
A
migrate as a group from allantois -> hindgut
18
Q
what 2 things do somatic cells around primordial germ cells secrete?
A
chemoattractants - help PGCs induce migration and survival factors
19
Q
teratomas
A
tumours that form when PCGs grow outside genital ridge = can grow teeth & hair b/c these cells have potential for development
20
Q
what is the genital ridge & where does it form?
A
where gonads develop, forms near embryonic kidneys
21
Q
bipotential gonad
A
development is unknown but can become ovary or testes later
22
Q
primitive sex cords
A
compact strands of tissue that incorporate PGCs & allow formation of gonad
23
Q
paramesonephric duct
A
mullerian duct
24
Q
T or F: no single factor is responsible for activation of ovary or testes development in ALL vertebrates
A
T
25
SRY gene
stimulates production of a protein called TDF, females lack this gene
26
phenotypic sex
visual anatomic sex of an individual, depends on presence or absence of testes
27
what do wolffian ducts develop into?
the male reproductive tract
28
anti-mullerian hormone function
inhibits female duct system
29
testosterone is reduced to what?
DHT- dihydrotestosterone
30
FOXI2 vs SOX9 gene function
FOX-drives development of ovaries
SOX-produces antimullerian hormone
31
T or F: social stress from lack of male = cause female to form into male to fertilize the females egg
T
32
epigenic regulation
altering gene expression & phenotype without changing DNA sequence- genes get methylated (respressed)
33
how does sex determination work in turtle eggs in sand?
higher temperature forms females = demethylation (activation) of FOXI2
34
STAT-3 function
roles in temp & stress responses that lead to sex determination
35
cumulative process
long developmental window so changing fertilized eggs between temperatures can switch sexual development until specific development of gonads
36
why do gonads need a tightly regulated network of transcription factors & cell signalling molecules?
b/c disorders of sex development (DSDs) can occur
- infertility & dysfunction
37
polled intersex syndrome
a deletion in chromosome 1 that effects polled gene & FOXI2
- FOXI2: need 2 copies for effects
- polled: only need 1 copy
38
polled intersex goat phenotype for heterozygous male, infertile phenotypic male & phenotypic male
heterozygous male- polled & 1 FOXI2 gene
infertile phenotypic male- no FOXI2 gene, polled
phenotypic female: polled, 1 copy of FOXI2
39
turners syndrome
only 1 chromosome is present
40
hypoplastic ovary
underdeveloped ovary & small uterus
41
gonadal dysgenesis
lack of proper genes occurs when 1 X chromosome is present
42
infantile result from
lack of gonadal hormones
43
klinefelters syndrome
occurs from non-disjunction during meiosis
XXX female infertile
44
true parthenogenesis occurs in
females
45
how many species use parthenogenesis
80
46
obligate vs facultative parthenogenesis
obligate: only asexual reproduction
facultative: only sometimes uses sexual if stressed
47
why do mammals not use facultative parthenogenesis
mammals use genomic imprinting and require maternal genes & specific male genes at specific times
48
T or F: stingray can use parthenogenesis
T
49
obligate parthenogenesis
doubling of chromosomes in diploid state so they can replicate or fuse = creates diploid cell when normally a haploid would be formed
50
facultative parthenogenesis
diploid chromosome is restored by failure of 2nd meiotic division
51
what occurs if meiosis 2 division does occur in facultative parthenogenesis
polar body will fuse back with haploid & produce diploid
52
what structure allows germ cells to get incorporated into testes
from seminiferous tubules
53
how do testes develop
PCGs become incorporated in epithelial sex cords and driven by the presence of the Y chromosome
54
what is the mesonephros
transient form of the embryonic kidney that will not become the adult kidney
- it is used to produce the reproductive system when the adult kidney comes in
55
where is the anti-mullerian hormone secreted from?
sertoli cells
56
rete testis
network connecting cords so sperm can move into urethra
57
seminiferous cords
solid tubules that contain the germ cells - each one contains approx. 4 germ cells
58
what do interstitial cells produce
testosterone
59
excurrent extrgonadal duct system
direct tubular connection from place where sperm are produced to urethra, fluid is there to allow sperm to be flushed towards urethra as needed
60
what are seminiferous tubules developed from? what does it connect
developed from seminiferous cords, connects rete testis & efferent ducts
61
what indicates puberty
age
62
what animal reaches puberty earliest vs latest
earliest-sheep
latest-humans
63
what temp do testes require for spermatogenesis to occur
2-4 C below body temp
64
cryptorchidism
undescended testes, cannot modulate temp properly for spermatogenesis
65
where does spermatogenesis take place
seminiferous tubules
66
T or F: more mature sperm move slowly
T
67
gubernaculum
retracts to pull testes into scrotal sacs
68
how do aquatic animals with fins modulate testes temp?
fins have vascular supply that is cooled in flipper region & goes to testes first before rest of body so it doesn't warm up- no scrotal sac
69
T or F: elephants do not have testicular descent
T
70
unilateral vs bilateral cryptorchidism
unilateral-failure of 1 testes to descend, low fertility, most common
bilateral- failure of both testes to descend, infertile
71
disadvantage of cryptorchidism
testosterone is still produced so can have intact male behaviour but actual spermatogenesis does not occur
72
2 ways cryptorchidism can be diganosed
ultrasound or radiograph
73
what is the most common disorder of sexual differentiation in humans
cryptorchidism
74
why should undescended testes be removed?
b/c they can develop into tumours & still produce testosterone = intact male behaviours
75
effects of testosterone before & after birth
before: masculinizes reproductive tract & descent of testes
after: growth & maturation of reproductive system & spermatogenesis
76
2 other effects of testosterone
develops sex drive & controls gonadotropic hormone secretion
77
secondary sexual characteristics of testosterone
deepening of voice, hair growth, muscle growth
78
3 non-reproductive actions of testosterone
bone growth at puberty, aggressive behaviour & protein anabolic effects
79
puberty
achievement by the gonads of their complete hormonal & gametogenic capacity
80
how is puberty signalled?
increase & frequency of secretion of GnRH from hypothalamus
81
what does puberty activate
HPG axis- produce androgens to help with adolescent growth
82
what does puberty do to LH & FSH
stimulates their increased pulses in pituitary gland
83
T or F: LH & FSH is in males & females
T
84
what does LH & FSH activate?
steroidgenesis & gametogenesis
85
most of the time, puberty is
gradual
86
T or F: in female domestic animals, puberty occurs before physical maturity
T
87
LH vs FSH pulsability
LH- pulsatile
FSH- not puslatile
88
spermatozoa
mature male gametes
89
3 parts of a sperm
1) head: acrosome that penetrates the egg
2) midpiece: contain mitochondria for energy to swim
3) tail: motility
90
where are germ cells located
periphery of seminiferous tubule
91
as you move toward the lumen, you get
more mature sperm
92
why does spermatogenesis duration vary?
they are at different stages so they can take over & not have to wait another 64 days
93
mitotic proliferation
spermatogonia divide & form primary spermatocytes
94
meiosis in relation to sperm
1st division- primary spermatocyte divides into 2 secondary spermatocytes
2nd division- forms four spermatids
95
spermiogenesis
spermatids are packaged into spermatozoa
96
3 stages to spermatogenesis
1) mitotic proliferation
2) meiosis
3) spermiogenesis
97
T or F: mitotic proliferation of spermatogonia allows continual supply of new diploid germ cells
T
98
why is duplication in meiosis 1 required
each strand becomes a chromosome itself b/c it was a copy of the original chromosome so we maintain the haploid state
99
cytoplasmic bridging
important in males, allows cytoplasm to exchange key proteins between these cells that are attached by cytoplasmic bridges
100
why are sertoli cells important
they are tightly bound to each other & they surround the developing sperm until they are released into the lumen
they attach via gap junctions to allow passage from blood plasma
101
what is produced as a source of energy for the sperm
lactate
102
5 functions of sertoli cells
1) nourish developing sperm with lactate
2) eat cytoplasm
3) destroy defective germ cells
4) secrete tubule fluid
5) produce androgen-binding protein
103
androgen binding protein
acts like a sink & binds testosterone so its levels are kept at a higher level around the sperm to drive spermatogenesis
104
how is testicular function regulated?
LH- acts on interstitial cells to regulate testosterone secretion
FSH- acts on sertoli cells to stimulate spermatogenesis
their secretions are stimulated or inhibited by GnRH
105
aromatase activity has function in
mammal brain
106
how sperm that are ready for ejaculation transported?
efferent ducts -> epididymis -> ductus deferens -> ejaculatory duct -> urethra
107
T or F: sperm can fertilize as they move through the epididymis
T
108
how are sperm pushed through the reproductive tract
peristaltic contractions
109
ductus deferens
muscular tube that passes out of scrotum & into pelvic cavity
- sperm storage
- muscular contractions push sperm into urethra
110
ampulla
enlarged portion of ductus deferens just before entrance to urethra
111
ejaculatory duct
thick smooth muscle layers that push sperm towards urethra for sperm ejaculation
112
where is seminal fluid most secreted from
male accessory sex glands
113
what male accessory sex glands are not found in dogs
bulbourethral gland
seminal vesicles - cats & dogs
114
3 seminal vesicles secretions
1) secrete fructose for sperm energy
2) secrete prostagandins - stimulate smooth muscle contractions
3) secrete fibrinogen- form clots
115
what does prostaglandins do
stimulate smooth muscle contractions in male & female reproductive tracts
116
prostate gland functions (3)
1) secretes alkaline function to neutralize acidic vaginal secretions
2) provides clotting enzymes to reduce semen loss
3) releases prostate-specific antigen
117
prostate specific antigen
breaks down seminal clot after entering female tract so sperm can move to oocyte
118
bulbourethral gland function
secrete mucous for lubrication & to neutralize acidic pH of urethra
119
3 parts of the penis
1) root
2) body/shaft- erectile tissue
3) glans-supplied with nerves to respond to erectile tissues
120
T or F: penis extends, not in size or diameter much
T
121
fibroelastic penis
contains lots of connective tissues
122
musculocavernous penis & what species
large cavernous spaces of erectile tissue - horse
123
what penis do snakes have
hemipenis
124
what penis type do dogs have
osteomusculocavernous- bony
125
when does mating occur
at peak of fertility (estrus)
126
perineal region
pelvic floor that emits odours smelt by both sexes for mating
127
flehmen reaction
raised upper lip & raised head from vomeronasal organ
128
vomeronasal organ
found in platate between nasal & organ cavities b/c duct sample the air for phermones & determine if this female is enough for mating
129
3 signals that females are receptive
1) squatting
2) moving tail side to side
3) remaining stationary
130
lordosis
behaviour of remaining stationary
131
erection
straightening & hardening of penis for entry into vagina
132
ejaculation
forceful explusion of semen into urethra & out of penis
133
sexual response cycle stages (5)
1) excitement phase- heightened sexual awareness
2) plateau phase-increased heart rate, blood pressure, respiratory rate & muscle tension
3) orgasmic phase-ejaculation & stimulation of pleasure centers in brain
4) resolution phase- genitalia & body systems return to pre-arousal state
134
body of penis has ( ) columns of spongelike vascular spaces
3
135
what 3 things occurs during sexual arousal
arterioles dilate & erectile tissue fills with blood = erection & venous outflow is reduced for penetration
136
erection reflex
spinal reflex in PNS triggered by mechanoreceotors in glans penis, mediated by nitric oxide
- inhibits SNS b/c ensures arterioles are closed
137
how is erectile dysfunction treated?
stimulate nitric oxide production
138
where is erection generating centre found
sacral region of spinal cord from S2-S4
139
how do mechanoreceptors work in erection generating centre
mechanoreceptors stimulate sacral region & inhibits SNS & promotes PNS pathway to get vasodilation = increased bloodflow to penis
140
PNS vasodilation causes
relaxation of penile arteriole smooth muscle by production of nitric oxide
141
what does nitric oxide activate?
sGC - takes GTP & converts it to cGMP = allows relaxation of smooth muscle
142
SNS causes
vas deferns contraction & delivery of semen into urethra = triggers nerve impulses
143
what stops semen from entering urine & vice versa?
sphincter at neck of bladder
144
whatis released from a male orgasm
oxytocin release from pituitary gland
145
resolution of male
pathway gets sensitized & can only last for a short period of time so as it becomes sensitized the SNS system begins to take control again = slower blood flow into penis = erection decreases = returns to pre-arousal state
146
tactile stimulation of female erectile tissue is
clitoris- generates spinal reflex
147
why can females have multiple orgasms
pathway is not as easily sensitized
148
ART
assisted reproduction technologies
149
energy input for food production from animal sources is decreased by
the number of offspring per unit of time the breeding female can produce in the herd
150
why use ART
genetic selection & save rare species
151
what is the 1st way of doing ART
hormone therapy
152
what is most common ART
AI, relies on cryopreservation
153
extenders
reagents to extend protection/life of semen
154
what temp of semen is best for AI in cattle
frozen semen
155
why must extenders be iso-osmotic
avoid water flow in/out of sperm
156
what is a good buffer for extenders
hepes, pH of 7-7
157
why do we add casein & egg yolks to sperm in AI?
casein- coats the sperm & protects them from dilation shock
yolk-cold shock protection - has lots of lypoprotein
158
what 2 antibiotics are used in AI extenders
gentamycin & pencillin
159
cryopreservation
semen is placed in straws, cooled to 4 degrees C, frozen & stored in liquid nitrogen
160
where must semen be deposited directly into for AI
uterus
161
3 types of AI techniques
1) conventional- semen injected into cervix using corkscrew pipette
2) tubular extension- into uterus
3) 2 prong approach-double insemination -uterine horn & cervix
162
sexed semen sorting uses
flow cytometry
163
flow cytometry
visible sperm & cells to separate X & Y chromosome, stain X chromosome
- creates droplets of sperm & UV laser is used to detect stained chromosomes & then analyzed by computer
164
T or F: X chromosome is larger than Y
T
165
sexed semen is used mostly by which industry & why?
dairy b/c we want female cows for milking & to avoid slaughter or males = animal welfare issues
166
monotocous vs polytomous species
m=gives 1 offspring (cow)
p=multiple offspring (pigs)
167
2 advantages of embryo transfer
1) increased production of offspring
2) enhance genetic diversity across the globe by shipping embryos
168
5 steps for embryo transfer
1) synchronize cycles of donor & recipient
2) superovulation of donor
3) inseminate into both uterine horns with pipette
4) collect embryos using folly catheter
5) transfer embryos
169
folly catheter
flush out embryos & collect them in a tube with filter
170
3 disadvantages of embryo transfer
1) less offspring produced
2) superovulation response can be poor
3) recovery of embryos is invasive
171
ultrasound guided ovum pick up
more invasive, in vitro fertilization, culture embryos & then put into recipients
172
bison use ( ) for ultrasound guided ovum pick up b/c wild animals are dangerous
electroejaculation
173
somatic cell nuclear transfer / cloning
donor provides cells -> nuclei get removed -> collect oocyte & remove that nuclei & replace with donor nuclei = can be fertilized & used to create new individuals
174
what was first somatic cell nuclear transfer animal
dolly the sheep, had abnormalities
175
1 advantage & 1 disadvantage to somatic cell nuclear transfer
enables preservation & rederivation of elite animals or endangered species
low efficiency & abnormalities
176
3 functions of male reproductive system
1) spermatogenesis
2) delivery of sperm
3) produce androgens
177
vans deferns
tubes that bring sperm to penis
178
T or F: birds lack male accessory sex glands
T
179
what does the tonic center regulate
basal pulse frequency
180
how does testosterone inhibit LH secretion
negative feedback
181
where is inhibin secreted from
sertoli cells
182
what does inhibin act on
anterior pit to inhibit FSH secretion
183
what does an increase in LH cause in feedback loop
increase in leydig cells
184
what does an increase in testosterone cause in feedback loop
inhibits LH secretion
185
what does an increase in GnRh cause in feedback loop
increase in LH & FSH
186
what does an increase in FSH cause in feedback loop
spermatogenesis & inhibin increase
187
what does an increase in inhibin cause in feedback loop
decrease in FSH
188
HGP axis function
produce androgens to help with adolescent growth
