Male Reproductive Physiology Flashcards
What is included in the male reproductive organs?
Testes, epididymis, ductus deferens, prostate gland, bulbourethral gland and penis
Describe the normal process of ejaculation
Sperm are created in testes
Sperm travels through vas deferens to urethra
Seminal vesicles and prostate crate semen - carried along with sperm in urethra
Describe the structure of the testes
Tunica albuginea - fibrous capsule
Seminiferous tubules - lobules
Head, body and tail of epididymis
Vas deferens
What are the three types of cells within the seminiferous tubules?
Germ cells
Sertoli/ sustentacular cells
Interstitial (Leydig) cells
What do germ cells produce in males?
Sperm
What do sertoli/ sustentacular cells produce?
Support sperm producing cells
Produce inhibin
What do interstitial (Leydig) cells produce?
Testosterone
What are the function of testes?
Sperm production
Testosterone production
What is the average time from production of sperm to ejaculation?
64 days - average cycle is 3 months
Millions of viable sperm are produced per day
What does testosterone production control?
Spermatogenesis
What are the reproductive hormones involved in the endocrine control of testicular function?
GnRH produced from hypothalamus
Gonadotrophins - FSH and LH from anterior pituitary
Testosterone from testes
What is the role of FSH on the testes?
Sperm cells facilitate spermatogenesis
What is the role of LH on the testes?
Leydig cells to produce testosterone
Describe the negative feedback effects in endocrine control of testes
Testosterone and inhibin inhibit secretion of GnRH by the hypothalamus
LH and FSH inhibits by the pituitary
What are the 2 stages of spermatogenesis?
Spermatocytogenesis
Spermiogenesis
When does the process of spermatogenesis start?
Starts at puberty and is lifelong
Describe spermatocytogenesis
Clonal expansion and maturation through mitotic and meiotic process
Describe spermiogenesis
Differentiation into mature sperm cells
What processes are involved in the clonal expansion and maturation of spermatocytogenesis?
1 mitotic and 2 meiotic divisions
Leads to spermatids being produced
What is the end result of spermiogenesis?
Sperm which is capable for fertilisation as has acquired functional capacity
Describe the first mitotic division during spermatogenesis
Spermatogonium to primary spermatocyte which has diploid chromosome number - 46
Describe the first meiotic division during spermatogenesis
Primary spermatocyte to secondary spermatocyte - 2 cells with haploid chromosome number - 23
Describe the second meiotic division during spermatogenesis
Secondary spermatocyte to spermatid, 2 cells with haploid chromosome number - 23
What are the factors affecting spermatogenesis?
Medical, lifestyle or both can lead to male infertility
What are the 2 types of medical factors affecting spermatogenesis?
Pretesticular - problem with the hormonal control
Testicular - problem at the site of production
What can cause pretesticular medical factors affecting spermatogenesis?
Functional - weight loss or gain
Intracranial tumours, cysts or bleeds
Prolactinoma
Medications - opiates, external testosterone and steroids
Genetic - Kallmann’s syndrome
What can cause testicular medical factors affecting spermatogenesis?
Surgery - orchidectomy and orchidopexy
STI
Mumps orchitis
Testicular trauma or torsion
RT or chemo
Genetic - Klinefelter’s and Y chromosome microdeletion
What are some environmental/ lifestyle factors affecting spermatogenesis?
Traffic/ diesel exhaust
Occupational and chemical exposures
Sedentary position
Reduced testosterone and increased oestradiol
Obesity and smoking
What are maternal factors affecting spermatogenesis?
Mother factors are irreversible
Obesity, persistent organic pollutants, diesel, smoking, use of cosmetics
What are some steps to recue the impact of factors affecting fertility?
Improve lifestyle - BMI, smoking, alcohol, diet, occupation
Optimise underlying medical condition
Stop medications
Reduce STI risk
Fertility preservation
What is the normal sperm count?
More than 15 million/ ml
Motility is more than 32% of sample
What are clues for pretesticular causes affecting spermatogenesis?
Systemic illness, chemo, prolactinoma, Kallmann’s, medication/ steroid use, extreme exercise and weight gain/ loss
What are clues for testicular causes affecting spermatogenesis?
STI, testes trauma or torsion, surgery, varicocele and genetic
What are clues for lifestyle affecting spermatogenesis?
Heat, smoking, BMI, excessive alcohol, recreational drug use, occupation exposure to chemical, heavy metal and radiation
What are some investigations used for male infertility?
BMI, genetic exam, USS testes, hormonal profile and genetic test
What can be seen in examination for male infertility?
High BMI
Small testes, varicocele, surgical scar
Absence of vas deferens in CF
What can be seen in hormonal profile for male infertility?
Low FSH, LH, prolactin and testosterone from hypothalamus or pituitary cause - hypogonadotropic hypogonadism
High prolactin
Testicular cause - high FSH, LH but low testosterone
What can genetic tests show in male infertility?
Abnormal karyotype, CF and microdeletion
What can be shown on USS testes in male infertility?
Testicular volume, hydrocele, varicocele and cancer
