Repro 4 - Male Reproductive Tract Flashcards
The scrotum should have a well-defined
Scrotal neck
What does the scrotal neck allow the scrotum to do
Move away from the abdomen (to keep them cooler than body temperature)
What scrotum types can you have (ew)
Straight-sided (more fat around neck), normal, short scrotal neck (normal for cold temps, but not for permanent configuration)
Testis are maintained 4-6°C lower than core body temperature to ensure
Normal spermatogenesis
The testis maintained at a lower temperature is accomplished by
The countercurrent heat exchange mechanism existing between the testicular artery and pampinoform plexus of the testicular vascular cone
Testicular vascular cone is made up of
Venous network + artery
Countercurrent heat exchange mechanism in testis functions:
Regulates testicular temperature
reduces pulse pressure
maintains high concentration of testosterone
Interstitium (Leydig cells) work with Sertoli cells to make
Testosterone
Seminiferous (SNF) tubules are made up of
Sertoli cells and germ cells
Where are germ cells located in
Sit on basement membrane
Leydig cells are similar to what cell in females
Theca interna
Sertoli cells are equivalent to what cells in females
Granulosa cells
Leydig cells have receptors for
LH
Sertoli cells have receptors for
FSH
Leydig cells secrete
Testosterone
Sertoli cells convert testosterone to
Estrogen
Sertoli cells secrete
Antigen Binding Protein, inhibit, activin, estrogens, lactate, pyruvate, and tubal fluid (metabolic agents needed for Sertoli cell function)
What makes up the blood-testis barrier
Sertoli cells are joined by specialized tight junctions forming basal and adluminal compartments
What does the blood-testis barrier protect
Immunologically privileged site for haploid cells (helps to hide sperm cells from body because they’re haploid, so considered foreign)
In the male, are hormone releases episodic or cyclic?
Episodic - which is why male sexual activity stays constant compared to females
2 prominent regions of sperm:
1) head
2) tail
Sperm structure: listed from head to tail
Acrosome, nucleus, plasma membrane, neck, middle piece, principal piece, then end piece
What is the longest part of the sperm
Principal piece
Acrosome integrity is essential for
Normal fertilization purposes
What does the outer dense fibre provide?
Structural stability
Where do sperm have mitochondria?
Only in midpiece
In principal piece, mitochondria are replaced by the
Fibrous sheath
In the tail of sperm, what is the arrangement of the cytoskeleton?
9+2 microtubule arrangement
3 stages of spermatogenesis
Proliferation, meiosis, and differentiation
Primary spermatocytes converting to secondary spermatocytes is which meiotic division?
1st
Going from secondary spermatocytes to spermatids is which meiosis division?
2nd meiotic division
Sperm precursor cells undergoing meiotic division are protected from the immune system by the formation of tight junctions between
Sertoli cells
Spherical spermatids differentiate into sperm through 4 phases:
Sperm DNA condensation, acrosome formation, formation of sperm tail for motility6, and formation of a metabolic “powerplant” (mitochondrial sheath)
Spermiogenesis (differentiation) is accomplished through 4 phases:
Golgi phase, cap phase, acrosomal phase, and maturation phase
The Golgi phase =
Acrosomal vesicle formation
During the Golgi phase, what shape is the spermatid
Spherical spermatic with a well developed Golgi apparatus
During the Golgi phase, what does the Golgi apparatus give rise to?
Golgi apparatus gives rise to proacrosomic granules which then fuse together to form acrosomal granule
What contains the acrosomic granule
Acrosomic vesicle
Which centrioles appear during the Golgi phase
Proximal and distal centrioles. They appear beneath the nucleus opposite to the acrosomal vesicle
What does the distal centriole become
The sperm tubule - becomes 9+2 microtubule
What is the cap phase
Spreading of the acrosomic vesicle over the nucleus
What is the shape of the spermatid during the cap phase
Cap-like formation of acrosome at the anterior portion of the nucleus
During the cap phase, what happens to the Golgi apparatus
It disappears
What does the distal centriole give rise to
The developing axoneme, which begins to project toward the lumen of the seminiferous tubule
Does tail formation happen during the cap phase?
Yes! It begins in this phase
What happens during the acrosomal phase
Nuclear and cytoplasmic elongation
During the acrosomal phase, the acrosome continues to spread and nucleus begins to ______
Elongate
What phase does the Manchette start to form?
Acrosomal phase
What is the manchette?
Microtubule based sleeve-like structure
Which direction does the manchette form
On the caudal half of the nucleus, and continues growing caudally
Are all components of developing spermatid enclosed by a plasma membrane?
Yes
How does the nucleus elongate?
Manchette wraps around middle of nucleus, then contracts and pulls down. By this process, the nucleus gets pulled down as well, leading to elongation
What happens if the manchette messes up
One cause of morphologically bad sperm
What is the maturation phase of sperm development
Final assembly
What happens to the manchette during the maturation phase
It disappears
What happens to mitochondria during the maturation phase
Mitochondria cluster around the anterior portion of the flagellum
Which section of the sperm contain mitochondria?
Midpiece
How do the mitochondria move to the midpiece of sperm?
Mitochondria contain proteins that are attracted to midpiece of sperm
During the maturation phase, what absorbs the extra cytoplasm?
Sertoli cells
What is spermiation?
Release of sperm into the lumen of the seminiferous tubules
What is the duration of spermatogenesis in bulls?
61 days (time to release of fully formed sperm into lumen of seminiferous tubules)
Spermatid journey from lumen of seminiferous tubules
Rete testis —> efferent ducts —> head of epididymus —> body of epididymus —> tail of epididymus —> ductus deferents
What is the rete testis?
Tubular network carrying sperm form SNF tubules to efferent ducts
What is the mediastinum?
Holds the rete testis in place
Sperm in the head of epididymus takes ___________ days to reach the tail of epididymus
8-11 days - also called epididymal transport
Are the 3 regions of the epididymus functionally distinct?
Yes! Sperm goes through different modifications in each of the 3 regions
What region of the epididymus are fully functional sperm stored?
Tail of epididymus
Does T4 influence epididymal function?
Yes
What is sperm DNA condensation?
Sperm cells have protamines instead of histones - DNA condensation during spermatogenesis in epididymus
Transport of proximal cytoplasmic droplet (PD) to a distal location (DD) happens in the
Body to Tail of epididymus
Transport of proximal cytoplasmic droplet (PD) to a distal location (DD) happens in the
Body to tail of epididymus. By the time sperm get to the tail of the epididymus, all sperm will have the distal droplet between their end piece and tail
During resorption of fluid, what gets resorbed?
Distal droplet
What happens to abnormal sperm?
Phagocytosis
Tail of epididymus stores _____________
Mature sperm with the capacity for motility
In yearlings during puberty, you may see what kind of sperm in tail of epididymus?
Cells with proximal cytoplasmic droplet
Which accessory sex glands do bulls, stallions, and boars all have?
Vesicular glands, prostate, and bulbourethral gland (BUG)
in the boar, the BUG (bulbourethral gland) secretes a ____________, which causes ____________
Viscous fluid, which causes coagulation of seminal plasma following an ejaculation
Which accessory glands do a dog have?
Prostate
Which accessory glands do a cat have?
Bulbourethral and prostate
What does semen comprise
Sperm and seminal plasma
Seminal plasma is made up of
Fluids from the testis, epididymus, and accessory sex glands
What is seminal plasma rich in
Electrolytes, fructose, ascorbic acid, enzymes, vitamins, hormones, growth factors, and various proteins
What does seminal plasma do
Nourish sperm, cleans urethra, and serves as a vehicle for the delivery of sperm
