The Making of the Male Flashcards
(131 cards)
1
Q
where do the testicles form?
A
in the gonadal ridge of the foetus
2
Q
when do the testicles descend to scrotum?
A
before puberty
For many species - should be before or shortly after birth in most species
3
Q
What is anorchidism?
A
failure of testicular development (rare)
4
Q
cryptorchidism?
A
temporary of permanent failure to descend (testicles)
5
Q
retained testis?
A
normal steroidogenesis but no spermatogenesis. prone neoplasia
6
Q
what is scrotal positioning essential for?
A
for fertility
7
Q
structure of the testes?
A
usually symmetrically-paired ovoid structures
8
Q
where are the testes housed? what are the different types?
A
housed in scrotum
- pendulous
- non-pendulous
- intermediate
9
Q
pendulous scrotum?
A
e.g. bull and ram
they protrude (hang down) ventrally in inguinal region
10
Q
non-pendulous scrotum?
A
e.g. tom cat and boar
protrude caudally in perineal region
higher up closer to anus
close to the body wall
11
Q
intermediate scrotum?
A
e.g. stallion and dog
protrude into caudal inguinal region
between the two (non-pendulous and pendulous)
12
Q
when does fertile semen production begin?
A
at puberty
13
Q
what type of glands are the testes?
A
they are both exocrine and endocrine glands
14
Q
rete testes in stallion?
A
it is central in stallion and non-central in other species
- serves as a collcting reservoir for sperm
15
Q
two components of the testes?
A
interstitium
seminiferous tubules
16
Q
what does the interstitium component contain?
A
leydig cells for androgen synthesis
blood and lymphatic vessels
fibroblasts and connective tissue
17
Q
what does the seminiferous tubule component contain?
A
spermatogenesis
18
Q
how are the interstitium and seminiferous tubules components of the testes structurally and physiologically distinct?
A
cellular barriers form at puberty to limit movement of hydrophilic substances between compartments
19
Q
testicular parenchyma?
A
interstitial tissue and seminiferous tubules
20
Q
when does spermatogenesis begin?
A
at puberty
21
Q
DSO?
A
Daily sperm output
22
Q
describe the DSO?
A
increases from puberty and remains relatively constant through life
23
Q
how can DSO be estimated?
A
from scrotal dimensions
24
Q
what happens to DSO with old age?
A
decreases but doesn’t cease with old age
25
ideal scrotal circumference for bull and ram?
bull: >36cm
ram: >34cm
26
How do spermatocytes form spermatids?
1y spermatocytes (2n) > leptotene > zygotene > pachytene > diplotene > 2y spermatocytes > round spermatids (n)
27
round spermatids are hap/diploid?
haploid after spermeogenesis
28
what is spermiogenesis?
round > elongated > mature
29
what is spermination?
when the mature sperm is released
30
what happens to excess cytoplasm?
chromatin condensed
flagellum and midpiece form
acrosome formed
cytoplasm shed
31
spermatogenic cycles?
stage of spermatogenic cycle differs in adjacent regions of tubules
finite region of tubules releasing sperm at a given time
ordered progression
32
time for completion of spermatogenesis to occur - man? and duration of epithelial cycle?
64 days
16 days
33
time for completion of spermatogenesis to occur - bull? and duration of epithelial cycle?
54 days
13.5 days
34
time for completion of spermatogenesis to occur - ram? and duration of epithelial cycle?
49 days
12.25 days
35
time for completion of spermatogenesis to occur - boar? and duration of epithelial cycle?
34 days
8.5 days
36
time for completion of spermatogenesis to occur - stallion?
58 days
12.2 days
37
testosterone travels to sertoli cells, what does this do>
stimulate production of sperm
38
inihibin?????????????????/
it creates a negative feedback loop which keeps the production of semen under control and fairly constant - limits the reaction to the sertoli cells
39
increase in day length?
increase in LH pulses (LH pulses = an increase in LH levels)
40
if an animal has anorchidism - why should you remove the testes?
because the testes will be at a higher temp than they should be (at body temp) - they are more likely to develop cancer
41
if an animal has anorchidism - they are likely to be...
infertile
42
why do you wait until 18 months to castrate a dachshund?
it massively reduces the risk of them getting spinal issues later in life
43
why would you do a chemical castration?
possibly to an anxious animal - sometimes castrating them may make them worse so do a chemical castration and see how the animal responds - then make decision
44
how do you give a chemical castration?
give the animal an implant
45
what do testes hang from?
a vascular cone
46
apart from the vascular cone - what also holds up the testes?
connective tissue
47
why is it important to make sure that the ratio of males to females copulating is kept appropriate?
after a certain amount of females the semen will be immature - so they can have a drop in fertility after mating with so many females as the semen is not as likely to survive
48
what is the process of sperm production?
spermatogenesis
49
what do the seminiferous tubules of the testes do?
they produce sperm via spermatogenesis
50
what do the seminiferous tubules essentially act like?
a gland - in producing sperm
51
what is the male steroid hormone from the reproductive tract?
androgen
52
what cells are responsible for the synthesis of androgens?
Leydig cells
53
where are Leydig cells found?
in the interstitium of the testes
54
apart from the synthesis of androgen - what other functions does the interstitium of the testes have?
needs to provide all of the support for the development of sperm SO the blood + lymphatic vessels are found here AND fibroblasts and connective tissue
55
is the sperm haploid or diploid?
haploid
56
what is the need for the blood testis barrier?
to protect the sperm from the immune system attacking it and killing it off --> infertile
57
in order to prevent infertility - where does the development of spermatogenesis have to occur?
an immunologically privileged site and this is called the blood testis barrier
58
what do the sertoli cells do for the testes?
they control the environment and provide nutrition
59
where are the sertoli cells found?
in the seminiferous tubule itself
60
what cells is the blood testis barrier formed by?
the sertoli cells which are sitting in the seminiferous tubule and these are joined together using tight junctions
61
the sertoli cells being joined together with the seminiferous tubules by tight junctions ensures what?
it enables them to control the environment that the sperm are developing within
62
what happens when spermatogonia develops into spermatozoa?
it multiplies up and forms - primary spermatocytes, secondary spermatocytes then these develop into spermatids which then develop into spermatozoa
63
why do the spermatogonia need to multiply up?
so they can produce large numbers of sperm
64
if there is trauma to the testes - how can infertility happen?
it can compromise the blood testes barrier which can lead to infertility
65
where are the heads of the spermatozoa which are found within the lumen of the seminiferous tubule?
heads buried inside the sertoli cells because the sertoli cells are still controlling their differentiation and development
66
when does spermatogenesis begin?
at puberty
67
to reduce the chance of having a drop in fertility - what do males do as they approach breeding season?
they increase their sperm output
68
how can we tell if the males are increasing their sperm output?
the size of their scrotum will increase
69
breeding soundness exam of ram/bull?
measure the scrotal circumference
you cradle the scrotum - measure around the widest part
70
ideal size of the scrotum for a bull for breeding season?
36cm or over
71
ideal size of the scrotum for a ram for breeding season?
34cm or over
72
spermatogonia are?
germ cells
73
where are the spermatogonia sitting?
they are sitting by the basal lamina and they will go through mitosis every so often
74
why do spermatogonia go through mitosis?
partly to maintain their own numbers but also to multiply up
75
if the spermatogonia are multiplying up - what does this mean?
they are embarking on a wave of spermatogenesis
76
spermatogonia will produce...
spermatocytes
77
what do spermatocytes multiply by?
meiosis
78
what do spermatids differentiate into?
spermatozoa
79
where are the spermatagonia sitting?
in the basal compartment next to the basal lamina
80
sperm-testis barrier is created by what?
by the sertoli cells - the sperm cells have to pass through as they differentiate
81
at the spermatocyte stage, haploid or diploid?
diploid - as they pass through but then go through meiosis and later become haploid once safely past blood-testis barrier
82
how can primary spermatocytes and spermatogonia synchronise their activity?
the cytokinesis phase of mitosis is incomplete so they are all interconnected via their cell membranes
83
how can pyrexia make a male less fertile?
the increased body temperature - has acted as an insult to the sperm
84
round elongated mature sperm is part of what stage?
spermiogenesis
85
what stage is it where sperm are released?
spermiation
86
what are the changes that occur during spermiogenesis? (when the sperm is round, elongated and matured)
the chromatin will condense
flagellum + midpiece form
Acrosome formed
Cytoplasm shed
87
what is the point of the midpiece of the sperm?
it contains essentially all of the mitochondria - essentially a motor for the cell
88
what is the acrosome important for?
for fertilisation
89
what are the sub components of the flagellum?
principal piece and endpiece
90
to avoid all of the mature sperm being ready at the same time - what does the body?
it takes the seminiferous tubule network and has sections: day 1, one section starts developing, day 2, second section starts developing, day 3, third section starts developing etc. so there is continuous production of sperm
91
where has the spermatogonia been reproducing?
on the basal lamina
92
spermatogonia produces... resulting in formation of spermatozoa
primary spermatocytes, several days of changes before forming a secondary spermatocyte, atp they move up slightly from the basal lamina, then form spermatids and then go through several days then they form spermatozoa
93
once the spermatozoa are ready, what happens?
spermatozoa can travel off to the epididymis, mature and then be ejaculated
94
spermatogenic wave?
how far along the seminiferous tubule you go before you find the same thing again
95
spermatogenic cycle?
time to get from a germ cell to a spermatozoa
96
order: spermatids, primary/secondary spermatocytes, spermatozoa
primary spermatocytes, secondary spermatocytes, spermatids, spermatozoa (atp they are released)
97
days it takes for spermatogenesis to occur in bulls?
54
98
days it takes for spermatogenesis to occur in rams?
49
99
days it takes for spermatogenesis to occur in boar?
34
100
days it takes for spermatogenesis to occur in stallion?
58
101
duration of the spermatogenic wave in bulls?
13.5 days
102
duration of the spermatogenic wave in rams?
12.25 days
103
duration of the spermatogenic wave in boar?
8.5 days
104
duration of the spermatogenic wave in stallion?
12.2 days
105
semen from one day is different to semen from another day, how?
Semen from one day will have come from one lot of stem cells whereas semen from another day will have come from another lot of stem cells
106
spermatozoa = hap/dip?
haploid
107
LH?
luteinising hormone
108
what produces LH?
the anterior pituitary
109
which cells are very sensitive to LH?
leydig cells
110
what do the leydig cells produce?
testosterone
111
what functions does testosterone have?
reduces amount of GnRH produced
keeps sperm output constant
also stimulates the development of sperm
112
what does the testosterone do?
it travels in the blood to the hypothalamus and anterior pituitary and have a negative feedback effect
reduces amount of GnRH being produced
keeps sperm output roughly constant
113
apart from to the anterior pituitary and hypothalamus, where else does testosterone travel to?
the sertoli cells
114
what happens when the testosterone travels to the sertoli cells?
it stimulates the development of sperm
115
what is also travelling to the sertoli cells at the same time as testosterone?
follicle stimulating hormone (FSH)
116
what happens as a result of FSH going to the sertoli cells?
leads to development of sperm
and production of inhibin by sertoli cells
117
what effect does inhibin have?
negative feedback on the anterior pituitary - need to regulate this production so we don't get a positive feedback loop and keep production fairly constant
118
why is the negative feedback (caused by testosterone) of endocrine function partially lost during breeding season?
because the male is going to want to produce more semen at these points so you have a higher sperm output
119
what is the mechanism for their breeding season linked to?
day length
120
how is the mechanism for the males breeding season linked to day length?
presence of light affects the conversion of serotonin to melatonin within the pineal gland --> this affects the RFP neurons which then affect the respective neurones
121
as day length increases - what can you expect to see an increase in also?
LH pulses
122
what leads to males moving out of their breeding season? (for short day breeders)
a decrease in LH pulses
(opposite occurs for long day breeders)
123
once the spermatozoa has been produced, where do they travel?
to the epididymis -
124
what distinct parts is the epididymis divided into?
the head, body and tail
125
where is the spermatozoa produced?
in the seminiferous tubules
of the testes - then has to mature in epididymis where it can be stored
126
vas deferens?
the tube that the spermatozoa are going to trave along as they travel to the urethra to be ejaculated
127
what do the accessory sex organs do?
they add various substances to the sperm which get it ready for better survival in the female
128
where do the spermatozoa encounter the accessory sex organs?
as they travel along the vas deferens to the urethra
129
when does it become semen?
when the spermatozoa is mixed with all the substances from the accessory sex organs
130
where does the epididymis lie?
along the body of the testis and is attached with connective issue
131
