Spermatogenesis part 1 and 2 (draft)

Question 1

Explain how mature sperm are continuously produced from a stem cell niche by spermatogenesis

Answer 1

Step 1
Mitosis
Spermatogonia undergo this = lots of identical 2n cells and creates a stem cell niche
note - there is some loss via apoptosis

Step 2
meiosis (past the blood testis barrier)
Spermataocytes
Creates genetically diverse , haploid cells
(Primary spermatocytes —> meiosis I to add more here)

Step 3
- spermatogenesis ( the process of moving from round spermatids to elongated spermatids)
Starts as round Spermatids to long spermatids
Initial product = round spermatids

Question 2

Describe the structure and role of the blood-testis barrier

Answer 2

Sertolis cells line up with tight junctions between each other = blood testis barrier
IMPORTANT
Purpose is to stop the immune cells from attacking the haploid cells
as the haploid sperm cell do not look normal as they are haploid

Question 3

Describe the basic sperm structure

Answer 3

Question 4

Epigenetic silencing

Answer 4

During spermatogenesis, cells undergo the histone to protamine transition = very tightly packed DNA within the nucleus = chromatin condensation = transcriptional silent = cannot make new proteins

thus are on a timer and cannot repair itself

Question 5

part 1 take home points

Answer 5

Question 6

Explain independent regions during spermatogenesis

Answer 6

Initiate spermatogonia division at different time

Different systems, most common is 8. Referred to roman numerals

this means that there is always sperm being produced

Question 7

Differentiate between the spermatogenic cycle

Answer 7

• how long it takes for one sperm to develop start from.

Question 8

Seminiferous epithelium cycle

Answer 8

When this times by 4.5x is always the amount of time it takes one cell to fully develop

4. 5 is the co-efficient across all different species
   - eg 13.5 for the 8 stages, the time by 4.5 = 60 days ( this is now how long it takes for one sperm to develop)

Question 9

Generations in the epithelium***

Answer 9

Length of epithelium cycle = times between generations

Question 10

Generations in the epithelium

Answer 10

“Intracellular bridges” - where cytoplasms are joined, this allows synchronised development of 50ish sperms together as one generation to develop together as one.

Question 11

Difference between seminiferous epithelium cycle and spermatogenic cycle

Answer 11

Question 12

Stages and spermatic waves

Answer 12

Think of it as different time zone, each time zone, or Mexican wave.

Question 13

Describe factors which can impact the efficiency of spermatogenesis

Answer 13

1. Breakdown of BTB (blood testis barrier)
   a) severe physical trauma
   b) environmental toxicants
   c) heat stress
   d) pathological inflammation
2. diet deficiency
   - Vit A
   - Essential fatty acids
   - some AAs
   - Zinc, selenium, folate

Irradation
eg cancer treatment which attacks cells that a
Cause arrest in spermatogenesis in low levels
High level = permanent infertility

Excess heat
why? - 4-6 degrees below body heat.
Causes - high environmental temp, fever, crytorchidms

Toxic.drug
as it is a dividing cell it is more affected by these things

Spermatogenesis disease

Spermatogenesis endocrine disruption
HPG axis distruptio
No testosterone= no spermatogenesis
Endocrine