spermatogenesis Flashcards
(17 cards)
What is the primary aim of spermatogenesis?
To produce spermatozoa and provide a continual supply of male gametes through stem cell renewal
Additional aims include providing genetic diversity and maximizing reproduction through the production of billions of sperm each day.
Where does spermatogenesis occur?
In the seminiferous tubules, beginning near the basement membrane and moving towards the lumen as they mature
The process involves developing germ cells that are connected by intercellular bridges.
What are the three phases of spermatogenesis?
Proliferation, meiosis, and differentiation
Each phase has distinct roles in the development of spermatozoa.
What occurs during the proliferation phase of spermatogenesis?
All mitotic divisions of spermatogonia (diploid cells) occur, including A spermatogonia, I spermatogonia, and B spermatogonia
Stem cell renewal is crucial in this phase, allowing some cells to revert to their primitive state.
What is the outcome of the meiosis phase in spermatogenesis?
It guarantees genetic diversity and produces haploid spermatids
The second meiotic division reduces the chromosome number by half.
What is the differentiation phase in spermatogenesis?
Spermatids undergo differentiation into spermatozoa, developing a head, flagellum, mid piece, and principal piece
This phase includes several sub-phases: Golgi phase, Cap phase, Acrosomal phase, and Maturation phase.
What happens during the Golgi phase of sperm differentiation?
Formation of the acrosomal vesicle and migration of the proximal centriole
The acrosomal vesicle contains dense acrosomal granules necessary for penetration.
What occurs in the Cap phase of sperm differentiation?
Acrosomic vesicles spread along the nucleus forming a cap
This is essential for the subsequent acrosomal phase.
What is characterized by the Acrosomal phase in sperm differentiation?
Nuclear and cytoplasmic elongation, and formation of the neck and annulus
The manchette forms on the nucleus, extending down the developing flagellum.
What occurs during the maturation phase of sperm differentiation?
The manchette splits, mitochondria migrate to the flagellum, and the sperm is released from Sertoli cells into the lumen (spermiation)
The postnuclear cap forms at the top of the sperm.
What is the spermatogenic wave?
The variation along the seminiferous tubule showing generational differences in developing sperm cells
The outer cells are the least developed, while the inner ones are the most developed.
What is a key difference between spermatogenesis and oogenesis?
Spermatogenesis produces gametes continuously, while oogenesis produces a complete supply of gametes after birth and undergoes meiosis and ovulation in a pulsatile manner
Oocytes begin to undergo meiosis and ovulation every 3-4 weeks after puberty.
What are the main structural components of a spermatozoon?
Head and tail
The head contains the nucleus, acrosome, and postnuclear cap; the tail consists of the capitulum, middle piece, principal piece, and terminal piece.
What is the function of the acrosome in spermatozoa?
Contains enzymes needed for penetration, such as acrosin and hyaluronidase
The acrosome is a membrane-bound lysosome located at the anterior 2/3rds of the nucleus.
Fill in the blank: The _______ is made from highly keratinized keratinoid proteins making it insoluble.
Chromatin
What is the role of the mitochondrial sheath in spermatozoa?
Surrounds the coarse fibers of the tail in the middle piece and is arranged helically for movement
This arrangement is crucial for the motility of the sperm.
