Physiology - Basic Reproductive System (Male) Flashcards
What kind of cells are sperm cells produced from?
Primordial germ cells
What is the length of the average spermatogenesis cycle?
64 days
What are the 2 distinct phases in sperm development (spermatogenesis)?
- Spermatocytogenesis - Clonal expansion and maturation through mitotic and meiotic process
- Spermiogenesis - Differentiation into mature sperm cells
What does the process of sperm production begin and end?
Process starts at puberty and continues lifelong
What are the names used to describe the cells at each stage of production?
- Spermatogonia A
- Spermatogonia B
- Spermatocyte I
- Spermatocye II
- Spermatid
- Sperm
What are the names used to describe the cells at each stage of production?
- Spermatogonia A
- Spermatogonia B
- Spermatocyte I
- Spermatocye II
- Spermatid
- Sperm
How many mitotic divisions are there in sperm production?
1
What occurs in the mitotic division stage?
Spermatogonium to primary spermatocyte-duplication, diploid chromosomes number
How many meiotic divisions are there in sperm production?
2
What occurs in the first meiotic division?
Primary spermatocyte to secondary spermatocyte, two cells with haploid chromosome number
What occurs in the second meiotic division?
Secondary spermatocyte to spermatid, two cells with haploid chromosome number
What is spermatogenesis?
Maturation of spermatids into functional sperm
What factors can affect spermatogenesis?
- Medical
- Lifestyle
- Combination
What are the 2 kinds of medical factors affecting spermatogenesis?
- Pretesticular - Problem with the hormonal control
* Testicular - Problem at the site of production
What are pretesticular medical factors affecting spermatogenesis?
- Functional - excessive weight loss, gain
- Intracranial tumours, cysts, bleed
- Prolactinoma
- Medications - opiates, external testosterone, steroids (body building)
- Genetic - Kallmann’s syndrome
What are testicular medical factors affecting spermatogenesis?
- Surgery - orchidectomy, orchidopexy
- STI
- Mumps orchitis
- Testicular trauma or torsion
- Radiotherapy or chemotherapy
- Genetic - Klinefelter’s (46 XXY), Y-chromosome microdeletion
What are the lifestyle/environmental factors affecting spermatogenesis?
THESE ARE REVERSIBLE IN MEN •Smoking •Obesity •Traffic/diesel exhaust •Chemical exposure •Sedentary position - heat exposure
What are some steps to reduce the impact of factors affecting fertility?
- Improve lifestyle- normal BMI, stop smoking, alcohol in recommended limits, healthy diet, exercise, adjustments to occupational exposure
- Optimise underlying medical condition
- Stop medications or switch to alternative pregnancy compatible medications
- Reduce STI risk and treat promptly if diagnosed.
- Fertility preservation - sperm freezing prior to surgery or cancer treatment
What are the 3 types of cells present in the seminiferous tubules?
- Germ cells - produce sperm
- Sertoli/sustentacular cells - support sperm producing cell, PRODUCE INHIBIN
- Interstitial (Leydig) cells - produce testosterone
What are the 2 main functions of the testes?
- Sperm production
* Testosterone production
What is the role of testosterone?
- Male secondary sexual characters
* Controls spermatogenesis
Which reproduction hormones are involved in the control of testicular function and where are they released from?
- GnRH - Gonadotrophin releasing hormone, produced from hypothalamus
- Gonadotrophins - FSH and LH, released from anterior pituitary
- Testosterone - released from testicles
How do LH and FSH from the pituitary affect the testes?
They stimulate spermatogenesis and testosterone secretion by the testes
INTERACTION OF HORMONES
What is the action of testosterone and inhibin on other hormones?
They inhibit the secretion of GnRH by th hypothalamus and LH & FSH by the pituitary
