Spermiogenesis Flashcards
What is the role of the bulbourethral gland?
Produces mucus and fluid of the semen. Formerly known as Cowper’s gland
What does the seminal vesicle release?
Fructose to provide energy for sperm, prostaglandins for recognition by ovum and alkaline pH to combat the acidic environment of the vagina.
What are the components of the sperm?
Consists of acrosome, mitochondria, centriole and majorly, the nucleus.
What is the role of the acrosome?
Contains the proteolytic enzymes to digest the ovum
What are the features of spermatic mitochondria?
Elongated and span the length of the sperm, excluding the head
How do the lobes of the testis form?
From the congregation of the seminiferous tubules.
What is the rete testis?
The confluence of multiple seminiferous tubules which connect the testis to the epididymis.
What connects the testes lobes to the rete testis?
Straight seminiferous tubes
What is the outer covering of the testes?
Tunica vaginalis, which overlies the inner membrane of the tunica albuginea.
What is the tunica albuginea?
Fibrous tough membrane lining of the testis
Where are Ledwig cells found?
Septa of testis which are fibrous partitions between the seminiferous tubules
What are the walls of the testis composed of?
Myoid cells’
What is the epithelia of the testis?
Germinal epithelia which has tight and occluding junctions in between to regulate entry of epithelia
Where does spermatogenesis occur?
In the seminferous tubules in the gaps between the sertoli cells which make it up
What is mitosis?
Cell division from 2n -> 4n -> 2n and produces 2 identical daughter cells.
What is meiosis?
.
Cell division to produce gametes. 2n -> 4n -> 2n.
Eggs will have unequal cell divison of cyptoplasm so it produces 2 polar bodies. These undergo non DNA division and form the second polar body and 2n -> n.
Sperm will have unequal cell division and form two sperm with linked cyptoplasm. From 2n -> n, it separates the linkage to form 4 gametes
How does proliferation of sperm occur?
Occurs in the gaps between sertoli cells in the seminiferous tubules in the basolateral compartment. Begins from a diploid proliferative spermatogonia stem cell and meiosis I-> in the form of Spermatogonia Type B, leaves the basolateral to enter adluminal compartment and undergo two rounds of Meiosis and form a spermatozoa.
What is the process of spermatogenesis?
2n Proliferative spermatogenetic stem cell-> 16 spermatogenic A1 cells.
1 Spermatogonium cell A1 divides= 2 A2 spermatogonim -> 4 A3 spermatogonium cell -> 16 Spermatogonium A4 cell. This forms 32 daughter cells which is the intermediate resting spermatocyte cells. Divides to form 64 Spermatogonium B cells. These leave the adluminal compartment of the cell and begin the process of meiosis. In meiosis I, spermatogonium -> early spermatocyte. In Meiosis II early spermatocyte -> late spermatocyte. Late spermatocyte undergoes cytodifferentiation where the cytoplasmic chain is broken to form 4 unique spermatoza.
What determines number of cells from spermatogenic stem cell?
Number of mitotic cell division
What is a Sustencular cell nucleus?
Nucleus of supporting cells such as Sertoli. Sertoli cells are columnar and attached to epithelia of basement membrane via hemidesmosomes.
When does it change from diploid to haploid in spermatogenesis?
Resting primary spermatocyte divides into a secondary spermatophore which enters the adluminal compartment.
Are clones made from the spermatogonia?
No- different due to meiotic recombination at the chiasmata.
What is cytodifferentiation?
The process where the cytoplasmic tail is broken between the linked spermatids to form the protozoa
What is spermiogenesis?
Process of forming round spermatid -> streamlined spermatoza. This is via the goli apparatus forming vesicle around acrosome and centriole moving to opposite pole of the sperm. Microtubules form the flagella and mitochondria coalesces around the microtubules to form a midpole. The excess cytoplasm is removed by sertoli cells and this forms the characteristic protozoa.
What is sperm cycle?
Proliferation through mitosis -> meiosis I -> meiosis II -> spermiogenesis. At the end of each stage, as the cell gets closer th the lumen, the cell is replaced to ensure that the production of sperm is continuous.
What is the time cycle for spermiogenesis?
16 days for each stage and 4 stages = 64 days.
What happens at the end of each division stage?
Cell is replaced by its progenitor.
What is the spermatogenic wave?
Specific regions of the seminiferous tubules has specific phases of spermatogenesis as the cells leave to move to the next phase and are replaced by its progenitor.
