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Unit 12 – Assignment 4 – P6
Male primary and secondary sex organs:
Secondary:

Penis

http://www
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edu/~jfasick/docs/Spring%20Semester%20Lectures%20Chapt
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pdf

Primary:

Testes - The two testes are contained in a bag of skin called the scrotum
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One of them is to produce millions of male sex cells called sperm
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The hormones affect the way a man's body will develop
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The fluids provide the sperm cells with nutrients
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Penis and urethra - The penis has two functions
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Another one is to pass semen into the vagina of a woman during sexual intercourse
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A ring of muscle ensures there is no chance
of urine and semen getting mixed up
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Each month an egg or
ovum ripens and breaks out of its sac, a process called ovulation
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This is called an oviduct or
Fallopian tube
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Every month, an egg will develop and
become mature
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The cilia waft the egg along inside the egg tube
and into the uterus
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It is a muscular bag with a soft lining
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The cervix is a ring of muscle at the lower end of
the uterus
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Vagina - The vagina is a muscular tube that goes from the cervix to the outside of the woman's body
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The opening to the vagina
has folds of skin called labia that meet to form a vulva
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It is also used for passing urine from the body

How sperm and ova are produced
Sperm:
Spermatogenesis is the process whereby sperm are made
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The first divisions are
mitotic and produce many genetically identical cells called spermatogonia
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The primary spermatocytes then divide
by meiosis, The first meiotic division produces secondary spermatocytes, two from each primary
spermatocyte
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The final stage of spermatogenesis is differentiation of spermatozoa from the
spermatids
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A mature spermatozoon has a head which contains a
nucleus
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at the base of the tail where it joins
the sperm head, there are many mitochondria
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It provides for the propulsive force for
spermatozoa to swim
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Spermatogenesis is inhibited by
heat
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Ova:
Oogenesis is the production of the ova (the female equivalent to spermatogenesis)
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Primordial germ cells divide by mitosis
to produce many oogonia
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The follicle cells and the enclosed oogonia are called the
primary follicles
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At birth, there are up to 400,000
primary follicles in an ovary where they remain dormant until puberty
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Only about 400 primary follicles will mature over
the reproductive lifespan of the woman, the end of which is called menopause
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Ova usually develop only one at a
time
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Follicular liquid appears in cavities between the dividing follicle cells
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The mature follicle is called a
Graafian follicle and can be seen bulging at the surface of the ovary
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the first meiotic division occurs just before ovulation
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Ovulation is the release of the

secondary oocyte from the ovary into the abdominal cavity, where it is drawn into the oviduct
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The result is an ovum and another small polar body
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The polar bodies have no known function (other
than as means by which surplus genetic material can be deposited)
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e
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Her
oestrogen levels also remain high; this stops the pituitary gland from releasing more FHS ( so no new
eggs are developed and released during pregnancy)
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Question 2:
What is the structure of the ovaries and oogenesis?
Spermatogenesis in the testes is paralleled in the ovaries by oogenesis, the production of ova
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Ovarian
germinal epithelium is on the outside of the ovaries
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The oogonia become surrounded by follicle cells, also
derives by mitosis from the germinal epithelium
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They migrate to the centre of the ovary
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Hormones from the pituitary
gland then start the process of oogenesis
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The end of this period, when follicle
development stops, is called the menopause
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Ova usually develop on at a time
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Between the dividing follicle cells, cavities appear, filled with follicular liquid
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An outer fibrous theca externa
enclosed an inner vascular
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During development, a follicle grows from about 0
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The primary oocyte inside the follicle now divides by meiosis
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Ovulation is the release of the secondary oocyte from the ovary into
the abdominal cavity from where it is drawn into the oviduct
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The secondary then
produces the ovum and another small polar body
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The polar bodies have no
known function
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Question 3:
What is the structure of the testes?
As they mature the testes decent from the abdomen into two sacs of skin called scrotal sacs
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The seminiferous tubules are continuous with other tubules
called the casa differentia, epididymis and vasa differentia
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Cutting the vasa differentia prevents the passage of sperm to the outside
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Sperm at different stages of development are found inside the seminiferous tubules
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The tubules are held
together by connective tissue which contains interstitial cells, nerve fibres, blood and lymphatic
capillaries
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There are many
reasons why a person may struggle to have children e
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they may have problems with their organs,
they may be in a homosexual relationship or they may have passed the 'child-bearing' age
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The egg and sperm are put
together in a test tube with the hope of new life starting
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Artificial insemination is when the sperm is collected and places into the mothers uterus using
artificial methods
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Artificial insemination take place in two ways:
1
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If the partner has unhealthy sperm, or the woman does not have a male partner, then the
sperm will come from an anonymous donor
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LH
and FSH directly stimulate your ovaries to produce and ripen eggs
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"
Reference: www
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co
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It has been argued that it was often necessary to sit with a
patient to say they had come to the end of the line
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Preventing Birth Defects - An important scientific argument for IVF was that by studying
fertilization and early embryonic development outside the womb, scientists might learn
more about how to prevent certain birth defects
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Arguments against fertility treatment:
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Creating Sick or Malformed Babies - For the people who opposed IVF, there were a number
of reasons not to proceed
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It was feared that this would result in deformed babies with
terminal illnesses
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Unit 12 – Assignment 4- D4
Menstrual cycle
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Hormones from the pituitary gland, the adrenal cortex and the gonads are all required for the
regulation of the reproductive system
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Follicle
stimulating hormone stimulates gamete production, and luteinizing hormone stimulates the
production of hormones by the gonads (this occurs in both men and women)
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The processes are controlled by the size and frequency of gonadotropin-releasing hormone
pulses, as well as by feedback from androgens and oestrogens
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In males, follicle-stimulating hormone stimulates the primary
spermatocytes to go through the first stage of meiosis, to form secondary spermatocytes
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Follicle-stimulating hormone also enhances the production of
androgen-binding protein by the Sertoli cells of the testes
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The FSH production of folliclestimulating hormone is inhibited by the hormone inhibin; this is released by the testes
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The
most known androgen in males is testosterone (this is produced by the adrenal cortex); this
promotes the production of sperm and male characteristics
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Follicle cells produce inhibin; this inhibits the production of follicle-stimulating
hormone in the female reproductive system
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Progesterone and estradiol both prepare the body for pregnancy
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In females, after childbirth, the anterior part of the pituitary gland produces prolactin,
which stimulated the milk production by the mammary glands
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Dopamine inhibits the release of prolactin
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The
uterine smooth muscles are not sensitive to oxytocin until late in pregnancy, when there is a peak in
the number of oxytocin receptors in the uterus
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Until the birth is complete,
contractions increase in intensity as blood levels of oxytocin rise through a positive feedback
mechanism
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As the cells contract, milk is forced from the secretory alveoli into milk
ducts
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The suckling of an infant
stimulated the release of oxytocin; this triggers the synthesis of oxytocin in the hypothalamus and its
release into circulation at the posterior pituitary
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The following table provides some information regarding the parameters of what constitutes normal
seminal fluid:

Volume
pH
Sperm density
Total number of sperm
Motility
Morphology
Vitality
White blood cells

2
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2 – 8
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For the following statements, indicate whether they would be classed as normal using the
above parameters as a guide:

Parameter
Sperm density
pH
Motility
Morphology
pH
Total number of sperm
Vitality

Value
25000000 cm3
7
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9
5300000
59 out of 64 alive

Yes/No
yes
yes
yes
yes
no
no
yes

2
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He is
considering starting a regime of taking regular injections of testosterone (an anabolic steroid)
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Leydig cells in the testicles are 'activated' to produce
testosterone
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Anabolic steroids trick the
body into thinking that the testes do not have to produce testosterone
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When this happens, follicle stimulating hormone is not released
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This condition is reversible,
however, the longer a person uses anabolic steroids and the higher the dosage used, the more likely
this problem will become irreversible

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