Spermatogenesis Flashcards
Cells of the Tubular Compartment
- Sertoli Cells (Somatic cells)
- Germ cells
- Peritubular myoid cells (PTM)
They are the nurse cells, produces proteins and help in hormone regulation
Sertoli cells
These are the precursor cells of the spermatozoa
Germ cells
These are smooth muscle cells surrounding the basal lamina, part of the blood-testis barrier (BTB)
Peritubular myoid cells (PTM)
Cells of the Interstitial compartment
- Leydig cells
- Blood vessels
- Lymphatics
Testosterone transport protein
Androgen binding proteins (ABP)
Provides detergent effect that allows cells and fluid to move through the tubular network of the testes
Sulfated glycoproteins (SGP1 and 2)
Iron transport protein
Transferrin
FSH suppressor
Inhibin
Modulates libido, erectile function, and spermatogenesis
Estrogen
Spermatogenesis significance
- provide continual supply of male gametes
- provide genetic diversity
- provide billions of sperm each day to maximize reproduction
- provide an immunologically privileged site where germ cells are not destroyed by male’s immune system
It is between the basement membrane and junctional complexes, spermatogonia are also present
Basal compartment
It is the compartment from junctional complexes to the lumen
Adluminal compartment
Deep = ? Peripheral = ?
Spermatocytes ; Spermatids
Phases of Spermatogenesis
Proliferation (Mitotic) Phase -> Meiotic Phase -> Differentiation phase (Spermiogenesis)
Proliferation (Mitotic) Phase contain?
Spermatogonia -> Primary spermatocytes
Also stem cell renewal and apoptosis
Meiotic phase contain?
Primary spermatocytes -> Secondary spermatocytes -> Spermatids
Differentiation phase (Spermiogenesis) contains?
Spermatids -> Spermatozoa
The initial stage of spermatocytogenesis and takes place in the basal compartment of seminiferous tubule
Proliferation Phase
What triggers spermatogonia to undergo several mitotic divisions?
Retinoic acid pulses
Three types of spermatogonia found in the basal compartment
- Type A spermatogonia
- Type I (intermediate) spermatogonia
- Type B spermatogonia
How does the process Type B spermatogonia -> Primary spermatocytes occur?
Passes through the tight Sertoli cell junctions (part of BTB)
It is the final stage of spermatocytogenesis and occurs in the adluminal compartment of seminiferous tubules
Meiotic phase
These spermatocytes have the longest lifespan of all cell types
Primary lifespan
- Bull (18 - 19 days)
- Stallion (19 - 20 days)
These spermatocytes are short-lived
Secondary spermatocytes (1.1 - 1.7 days)
It is also called spermiogenesis and takes place in peripheral adluminal compartment
Differentiation Phase
What hormones govern the differentiation phase?
FSH and Testosterone
These are non-motile, round, and non-specialized
Spermatids
These are motile, elongate, specialized components, and special surface molecules
Spermatozoa
Phases of spermiogenesis
- Golgi phase
- Cap phase
- Acrosomal phase
- Maturation phase
Acrosomic vesicle formation in this phase
Golgi phase
Acrosomic vesicle spreads over the nucleus of the round spermatid and the flagellum starts to form
Cap phase
The spermatid nucleus and cytoplasm elongates, acrosome covers the majority of the anterior nucleus
Acrosomal phase
Mitochondria are assembled around the flagellum and the flagellumi is completely formed
Maturation phase
Parts of the spermatozoon’s head
- Nucleus
- Acrosome
- Post nuclear cap
It contains the genetic material
Nucleus
It is a bag of enzymes used to help the sperm enter the egg
Acrosome
It is located below the acrosome and is lateral to the nucleus
Post nuclear cap
These are parts of the Tail
- Capitulum
- Middle piece
- Principal piece
- Terminal piece
It is the attachment of the head to the tail, also known as the neck
Capitulum
Part of the middle piece; it gives the neck region motility
Laminated columns
Part of the middle piece; it provides energy
Mitochondrial helix
Part of the middle piece; junction of the middle piece and principal piece
Annulus
It makes up majority of the tail and is made up of microtubules, it also provides motility
Principal piece
It contains only the axoneme
Terminal piece
A cohort of cells that develop as a synchronous group
Cellular generations
Differences at any given instant time along the length of the seminiferous tubules
Spermatogenic wave
Sperm Ejaculation Pathway
Seminiferous tubules
Rete testis
Efferent ducts
Epididymal duct (Caput, Corpus, Cauda)
Deferent ducts
Ampulla (in Bull, Stallion, Ram)
Pelvic Urethra
Penile Urethra
Urethral Meatus
(Bull)
Total days required for 1 cycle of the seminiferous epithelium
Approximate days to complete spermatogenesis
13.5
61
(Ram)
Total days required for 1 cycle of the seminiferous epithelium
Approximate days to complete spermatogenesis
10.1
47
(Boar)
Total days required for 1 cycle of the seminiferous epithelium
Approximate days to complete spermatogenesis
8.3
39
(Stallion)
Total days required for 1 cycle of the seminiferous epithelium
Approximate days to complete spermatogenesis
12.2
55
