Week 1 - H - Spermatogenesis and male infertility (and intersex) Flashcards
What determines whether a person will be male or female sex? (sex is the biological factor)
The Y chromosome is what determines whether a person will be male or female
What does having a Y chromosome cause the development of? What does this produce?
The sex determining region of the Y chromosome (SRY)
This region of the Y chromosome causes the development of the testis
The testsis produce testosterone and anti-Mullerian factor
What is another name for the sex determining region of the Y chromosome? What are the two primitive genital tracts (Ducts)?
Another name is the testis determining factor
2 repro tracts:
Wollfian duct - male
Mullerian duct - female
What does the wolffian and mullerian ducts form?
Wolffian duct - male - forms the epididymis, vas deferens and seminal vesicles
Mullerian duct - female - becomes the fallopian tubes, uterus and upper 1/3rd of the vagina
Which cells in the testis produce tesosterone and anti-mullerian hormone?
Tetsis
Sertoli cells produce Anti-mullerian hormone
Leydig cells - produce tesosterone
What primitive genital tract does tesosterone and the anti-mullerian hormone promote the formation of?
The Wolffian duct
Without stimulus of male testicular hormones, fetus will develop female internal genital tract
What hormone is tesosterone converted to peripherally to cause the formation of male external genitalia?
testosterone is converted to dihydrotesosterone to cause this
Intersex people are born with any of several variations in sex characteristics including chromosomes, gonads, sex hormones, or genitals that, according to the UN Office of the High Commissioner for Human Rights, “do not fit the typical definitions for male or female bodies” What are two common conditions that cause intersex presentations?
Congenital adrenal hyperplasia
Androgen insensitivity syndrome
What sex (karatypically) does androgen insensitivity syndrome affect? What is it also known as?
Androgen insensitivty affects male sex babies (46 XY)
It is also known as testicular feminisation
What is the cause of androgen insensitivity syndrome (AIS)?
It is caused by there being a congenital insensitivity to androgens and therefore the undifferenitated external genitialia do not develop along male lines and instead develop along female lines
Androgen induction of Wolffian duct does not occur, Mullerian inhibition does occur As the induction of the wollfian duct does not occur (due to the andorgen receptors (testosterone is an androgen) dysfunctioning, some internal genitalia features are absent in males), as the mullerian inhibition occurs in AIS, what structures are not formed? Are testicles present in AIS?
Mullerian inhibition occurs as anti-mullerian hormone still works - therefore no uterus, upper 1/3rd of vaginaor uterine tubes
- Ovaries are also absent
Testicles are present but do not descend - typically found in the abdomen or inguinal canal
When does androgen insensitivity syndrome typically present and what are the symptoms?
Typically presents in puberty with primary amenorrhea and lack of pubic hair
In AIS, born external genitalia phenotypically female but chrososome wise you are male
People born with androgen insensitivity syndrome are sterile and therefore are unable to have children WHat is the mode of inheritance? If a female has it what is the likelihood of male child being affected by the condition? If a male has it what is the likelihood of passing it on?
It is an X-linked recessive disorder
Female carrier has it - 50% chance of male child being affected by the condition - this is becuase males only have one x chromosome and will therefore still be affected
Male has it - already affected and sterile so unable to pass the condition on
Will a child with congenital adrenal hyerplasia present as intersex in male or female?
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In utero, testes develop in abdominal cavity of fetus and drop into scrotal sac before birth (androgen-dependent) Why is it important that the testis descend?
This is because there is a lower outside body temperature and this will facilitate spermatogenesis
Temperature has to be lower than normal in order for spermatogenesis (sperm production) to take place. What are the two muscles that lower and raise the testis according to external temperature and therefore regulate the temp of the testes?
This is the dartos and cremaster muscle - contraction in these muscles rises/lowers the testis
What are undescended testis known as? WHat is the operation to surgically correct this known as? What happens to fertility?
Cryptorchidism - undescended testis
Orchidopexy - the surgical operation to move an undescended testi into the scrotum
Usually there is a reduced sperm count but the patient remains fertile if it is unilateral
If a child is born with undescended testes, when should an orchidopexy be performed by to reduce the risk of testicular germ cell cancer?
Should be performed before the child reaches 14 years of age
Where is sperm produced? What lies posterosuperiorly to the testis? What happens here? Where does the vas deferens lie in relation to the testes?
Sperm is produced in the seminiferous tubules of the testis
The epididymis is located at the posterosuperior aspect of the testis becoming the vas deferens inferiorly which runs superiroly on the posterior aspect of the testes
What innervation causes the penis to become erect and to ejaculate?
What are the three expandable erectile tissues along the length of the penis, which fill with blood during penile erection?
What tube does the urethra travel within in the penis?
Which tube gives rise to the glans of the penis?
- Parasympatehtic innervation - erection (point)
- Sympathetic innervation - ejaculation (shoot)
Corupus cavernosum x2 & the corpus spongiosum
Urethra travels within the coprus spongiosum
The corpus spongiosum gives rise to the glans of the penis
Sperm only becomes mature after the second meitoic devision Are spermatazoa or spermatids used for assisted conception treatment (ICSI) and why?
Mature spermatazoa is used for ACT as spermatids have a higher chance of mutation occurring
What is the name of the organelle that develops over the anterior half of the spermatozoa and contains the enzymes that breakdown the outer area of the ovum (the zona pellucida)? What provides the sperm with the energy for movement?
This is the acrosome - These enzymes break down the outer membrane of the ovum, called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum.
The mitochondria provide the sperm with ATP
LH and FSH are glycoproteins secreted by the anterior pituitarty What cells do they act upon? What does tesosterone have a negative feedback on?
LH acts on the leydig cells to cause testosterone production
FSH acts on the sertoli cells to aid in spermatogenesisi and produce inhibin/activin
Testpsterone has a negative feedback on the pituitary gland and the hypothalamus
What is the functions of the prostoglandins secreted in the fluid by the seminal gland? What is the joining of the seminal gland and the vas deferens known as?
The prostoglandins secreted stimulate sperm motility
Seminal gland duct + vas deferens = ejaculatory duct which enters the prostate gland
Describe the pathway from production of sperm to ejcaculation?
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