Lecture 2: Male Reproductive Physiology Flashcards
What four things are evaluated in a breeding soundness exam
- Bull fitness
- Semen quality
- Libido
- Ability to copulate
How is the bull fitness evaluated
Look at phenotypic presentation of hoofs, eyes, penis, seminal vesicles (purple)
What determines semen quality
Sperm motility, sperm morphology, scrotal circumference
There is relationship between teste size and ____
Timing of puberty in bulls daughter
How do you evaluate libido in breeding soundness exam
Arousal involves a cascade of endocrine and neural events that result in erection of the penis, mounting of the sexually responsive female, intromission and ejaculation
What are the 2 compartments and 3 cell types of testes
Compartments: seminiferous tubules and interstitial connective tissue
Cells: germ, sertoli, leydig
Where is the site of spermatogenesis
Seminiferous tubules
What cells eventually become sperm
Germ cells
What cells are involved in anti-mullerian hormone, androgen binding protein and inhibin
Sertoli cells
Testes produce two essential products:
Sperm and testosterone
Seminiferous tubules are encased by
Tunisia albuginea
Where is the site of sperm production
Seminiferous tubules
Sperm move through the ___ and into the ___ for storage and further maturation
Rete testes and epididymis
Upon emission sperm moves out through ____
Vas deferens
What is spermatogensis
Process by which Spermatogonia (germ cells) are converted to spermatozoa (sperms)
What is spermogenesis
Packaging and maturation of spermatozoa
Spermiation
Release of spermatozoa from Sertoli cells into lumen of the seminiferous tubules
What are the 3 steps of spermatogenesis
- Proliferation and differentiation of the Spermatogonia
- Meiosis of spermatocytes
- Spermatogenesis of spermatozoa
What are the steps in mitosis
- Spermatogonium (1 cell) to two daughter cells
- Spermatognia 2 daughter cells
- Generation of diploid primary spermatocytes
- Results in primary spermatocytes- double stranded DNA
What are the steps of meiosis
- First meiotic division which takes undifferentiated diploid germ cells to haploid spermatocytes- secondary spermatocytes
- Second meiotic division takes secondary spermatocytes and converts to 16 spermatids
- Results in spermatozoa, single strand of one chromosome
During embryonic development germ line cells help form the gonad and become ___
Spermatogonia
At puberty Spermatogonia undergo mitosis divisions to become _____
Primary spermatocytes
Each primary spermatocytes then enters the first meiotic division to become _____
Secondary spermatocytes
Each secondary spermatocytes enters the second round of meiosis producing two ____
Spermatids
Developing sperm cells do not complete cytokinesis during meiosis, therefore the four daughter cells remain connected forming a ___
Syncytium
The syncytium ensures that the haploid cells contain either a ___ or ____ and have access to all gene products available in a complete diploid genome
X or Y chromosome
Further maturation in the seminiferous tubule lumen create the ___
Spermatozoa
What is the purpose of temporal organization of the Spermatogenic cycle
Continuous production of sperm
The spermatogenic wave rate is set constant by ___
Retinoic acid within Sertoli cells
T or F: testosterone accelerates rate of the spermatogenic wave
False
A new cycle of spermatogenic wave begins every ___ days
12-14 days
How many days does it take to make sperm
63 days
How many days does it take to migrate to epididymis
14 days
What happens to the head of the spermatozoa when it converts from spermatids to spermatozoa
- Head elongates, most cytoplasm is lost
- Nucleus remodels- chromatic condensation
- Transcription ceases 2 weeks prior to sperm maturation
- ;lysosomes aggregate to form acrosome
What is the acrosome
Lysosomes at head of spermatozoa to break into oocyte
What is an important component of midpiece in spermatozoa
Mitochondria to power sperm
What is the purpose of the tail in spermatozoa
Microtubules move the flagellum tail
What forms the blood testes barrier between sertoli cells
Tight junctions
Developing sperm move between ___ between Sertoli cells to lumen
Tight junctions
What are two important functions for the tight junctions between sertoli cells
- Prevents immune cells from accessing genetically variant spermatozoa
- Required for fertility