Spermatozoa
Male gametes
Haploid cells
Spermatogenesis
Production and development of spermatozoa
Where does spermatogenesis occur?
Within the testes
Why are testes located on the external part of the body?
Because the internal body temperature is too high to support the development of spermatozoa
What houses the testes?
The scrotum
What happens to the scrotum when it is cold?
WIll contract and constrict
Causes the testes to be pulled closer to the body
Where is spermatogenesis initiated/synthesized?
Seminiferous Tubules
Seminiferous Tubules
Make up the central bulk of the testes
Are convoluted and divide into different lobules
What happens to spermatozoa as they develop?
They move towards the lumen of the seminiferous tubules and detach when they are ready to move to the next step of development
What are Leydig cells?
Specialized cells found in the interstitial space of the testes
What do Leydig cells secrete?
Androgens
What are androgens?
growth hormones
estrogen and testosterone
What are androgens necessary for?
The development of male gametes
What is the testes’ second major function?
Hormonal production
What conducts the testes’ second major function?
Leydig cells
What occurs during Spermatogenesis?
Spermatozoa start along the basal layer and divide so that each daughter cell contains the same amount of chromosomes as the parent cell (mitosis/diploid)
What happens after division in spermatogenesis?
One daughter cell remains towards the basal surface where it can further divide to form more daughter cells
The other daughter cell will move towards the apical surface where it will begin to divide more
What is another name for Type B spermatozoa?
Primary spermatocytes
What do primary spermatocytes undergo to become a secondary spermatocyte?
Meiosis
Secondary spermatocytes will undergo _____ once more to become ______
Meiosis; Spermatids
When does mitosis only occur?
When a spermatogonia becomes a primary spermatocyte
Daughter A and B cells
When does meiosis occur?
When a primary spermatocyte becomes a secondary spermatocyte
What does the division of mitosis and meiosis mean for the primary and secondary spermatocyte?
A primary spermatocyte will still have the same amount of chromosomes as the parent cell
The amount will only half when it divides into secondary spermatocytes
What chromosomes do male cells contain
X and Y
What chromosomes do female cells contain
X
What determines the genetic sex of the offspring?
Spermatozoa
What happens to the spermatids once they reach the lumen surface?
They undergo spermiogenesis
What happens during the spermiogenesis stage?
The cells will grow a single flagellate
What does the flagellate do?
It propels the cell through fluid as it reaches its destination
What happens if the cell does not grow a flagellate?
The efficiency of fertilization will be very low
Where does the final stage of maturity begin?
The epididymis
What do the seminiferous tubules conduct to move the immature spermatozoa to the epididymis?
Peristalsis
What do the spermatozoa gain when they enter the epididymis
Large amounts of mitochondria
What is the epididymis lined with that help move the immature sperm throughout the tubule?
Stereocilia
What else do the stereocilia aid in?
Reabsorb excess fluids
What are the functions of the Epididymis?
A storage site for spermatozoa
Maturity of spermatozoa until expulsion
Where do the spermatozoa enter upon release?
The Vas Deferens
What do the spermatozoa join up with?
The ejaculatory duct
What does the Vas Deferens travel within
The spermatic cord
What does the spermatic cord also contain?
The testes’ blood vessels and nerves
During development, what two organs descend through the inguinal ring of the peritoneal wall?
The testes and the spermatic cord
What organ does the ejaculatory duct pass through and what organ does it join with?
The prostate gland and the urethra
What do the urethra and the ejaculatory duct travel within?
The prostate
What is the function of the seminal vesicle?
To secrete fluid that makes up the seminal fluid (semen)
What is the function of the prostate gland?
Secrete substances that nourish spermatozoa
What species DO NOT have a seminal vesicle?
Dogs and cats
What species DO have a seminal vesicle?
Humans, cows, horses
What contains the penis?
The prepuce
What organ is located near the prostate and seminal vesicles?
The Bulbourethral Gland
What is the function of the bulbourethral gland?
Secrete a mucous fluid prior to the expulsion of spermatozoa to allow lubrication of the urethra
What species DOES NOT have a bulbourethral gland
Canines
What species DOES have a bulbourethral gland?
Cats and cows
What organ is located along the ventral caudal aspect of the penis?
The Bulb of Glans
What is the function of the bulb of glans
It swells with blood during copulation, making it larger than the vaginal opening
What does the swelling of the bulb of glans cause?
The male dog to become stuck to the female dog
What organ is found in bulls?
The sigmoid flexures
What is the sigmoid flexures?
An “S” shaped structure created by the urethra
What is the function of the sigmoid flexures?
To extend the penis past the prepuce
What are the penises of cats covered in?
Tiny barbs
What is the function of the tiny barbs?
To help keep male cats attached to female cats
True or False: Cats are induced ovulators
True