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Spermatogenesis and Oogenesis (lecture 5 Smith)

Terms in this set (35)

Process of the formation of sperm/spermatozoa
spermatogenesis
Spermatogenesis

-site of formation is _____ _____ of the testicle

-regulated by _____

-begins at ____

-rarely totally ceases
1. seminiferous tubules

2. Testosterone

3. puberty
______ ________ allows testosterone to stay high in testicle
pampiniform plexus
Hormone Regulation

-Testosterone secreted by _____ cells has a negative feedback
1. Leydig
Hormone Regulation

-_____ stim ____ cells to secrete testosterone

-____ stim _____ cells to produce inhibin and covert testosterone to estrogen
-This helps with spermiogenesis
1. LH, leydig
2. FSH, Sertoli
Hormone involved

-____ released in pulsatile fashion from anterior pituitary. Prevents ______ to sustained ____

-This results in _____ secretion is short and pulsatile

-What helps maintain high levels of testosterone in the testis
1. LH, refractoriness, LH

2. Testosterone

3. pampiniform plexus
Elevated Testosterone in testis is essential for ______

-What would you give for increased testosterone and libido
1. spermatogenesis

2. GnRH
GnRH to LH to Testosterone
...
Spermatogenesis

-What are the three biological events involved?
1. Mitosis
2. Meiosis
3. Spermiogenesis
Proliferation phases which allow for continual supply of germ cells
mitosis
Meiosis

-cells go _____ to _____
- allow for _____ ____
-ensures _____ _____
1. diploid to haploid
2. crossing over
3. genetic diversity
1 spermatocyte lead to how many spermatids?
4
Spermiogenesis

- dramatic morphological changes from ______ to _______
1. spermatids to spermatozoa
Spermatogenesis

-Spermatogonia migrate along _____ cells toward ____ of the tubule

-spermatogonia undergo maturation and become what?
-What occurs here?
1. Sertoli, lumen

2. primary spermatocytes
-mitosis
spermatogenesis

-This process is very ____ sensitive and can be impacted greatly by ____ changes in scrotum.
Impact today won't be seen till months later
1. heat, temperature
Meiosis

-Each _____ _____ undergoes meiosis and forms 2 ______ ____ with haploid (meiosis 1)

-Each ______ ______ also undergos meiosis and become ______ (meiosis 2)

-_____ eventually mature into ________ during spermiogenesis
1. primary spermatocytes, secondary spermatocytes

2. secondary spermatocyte, spermatids

3. spermatids, spermatozoa (sperm)
Want to be haploid cause don't want to many genes
...
Meiosis

-allows for _____ chromosome number to be reduced to the _____ number

-allow each sperm to have a ____ number of chromosomes. Oocyte would be the same

-At fertilization the two gametes will unite to form a ____ with a diploid chromosome count
1. diploid, haploid

2. haploid

3. zygote
Cycle of Seminiferous Tubule

-The progression through all stage at one location along a siminiferous tubule

-equals one "cycle"
...
cycle length is unique to each species

-Bull
-Stallion

Approximate days to complete spermatogenesis

-bull
-stallion
1. 13.5
2. 12.2

1. 61
2. 55
Stages of Cycle

-Arbitrarily defined cellular associations that transition one to the next at predictable intervals

-How many stages in the bull?

-how long does it take to transition through all stage or one cycle?

-complete spermatogenisis takes how many cycles? How many days is this?
1. 8

2. 13.5

3. 4.5
61
Importance of Temperature

-Spermatogenesis must occur how many degrees celcius cooler than body temperature?

-Must be able to efficiently thermoreg the testicles. What are some ways of doing this (5)

-associated _____ problems
1. 3-7

2. Scrotal sweating
-tunica dartos muscle
-cremaster muscle
-pampiniform plexus (counter
current flow)
-Position of testicles in scrotum

3. fertility
Blood Testis Barrier

-____ cells are joined by tight junctions which effectively create a barrier from immune system

-Serves to allow _____ of dev sperm to occur in a controlled env

-developing sperm are not allowed access to the _____ _____ where the immune system will recognize them as foreign
1. Sertoli

2. metabolism

3. interstitial space
Sex Determination

-one pair of chromosomes determines the sex of the animal

-Females only contribute ___

-males contribute ____ and _____

-sex of offspring is determined by whether an ____ or ____ bearing sperm fertilizes the oocyte (chromosomal sex)
1. X

2. X and Y

3. X or Y
Determined at time of fertilization

This leads to what?
chromosomal sex

gonadal sex
Sperm Anatomy

What are the three parts?
1. Head
2. Midpiece
3. Tail
Head

-contains ____
-____ _____ contains enzymes which aid in fertilization
1. dna
2. acrosome cap
Midpiece

-contain _____ which provide power for the tail action
1. mitochondria
Tail

-_____ like action provides movement
Flagellum
What is the name given for sperm and associated fluids which are ejaculated?
Semen
What contribute to this fluid volume with their secretions
Acessory sex glands
What are the 4 acessory sex glands?
1. Ampulla
2. Prostate
3. Seminal vesicles
4. Bulbourethral
What is the development of the oocyte
Oogenesis
Oogenesis

-During prenatal growth ____ which are germ cells undergo ____

-These ____ enter meiosis near the time of birth but remain resting in _____ until puberty when meiosis resumes in a few cells each cycle

-Similar to spermatogenesis but following oogenesis what is produced?
1. oogonia, mitosis

2. oogonia, prophase

3. 1 ovum and 3 polar bodies
Differences in Germ Cell Production

-Males constantly replenish germ cells through ongoing mitosis

-Females are born with all they will ever have and slowly deplete their supply

-great increase in number of sperm by mitosis in male

-oogenesis involves only a limited number of oogonia each cycle
...
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