Spermatogenesis and oogenesis Flashcards
How many chromosomes does Primary spermatocyte has
46 (2n)
Definition of spermatogenesis
Is the process by which the seminferous tubule of the testes produce haploid sperm.
Begins at puberty
Takes 65-75 days
How many chromosomes does secondary spermatocyte has
23 (n), haploid
how many chromosome a spermatid has
23 (n) haploid
How many chromosomes a spermatogonium has
46 (2n) Diploid.
What differentiates into spermatogonium
Primordial germ cell
When and where Primordial germ cell migrate from yolk sac?
To testes at 5 th week of fetal development
When spermatogonium wakes up?
Puberty
Process of spermiogenesis
-Spherical spermids transform into elongated, slender sperm
- Sertoli cells dispose of excess cytoplasm
- sperm are released from the Sertoli cells, a process known as spermiation
sperm (not able to swim yet) are released into the lumen of the semiferous tubles and are pushed through the tubules by fluid produced by Sertoli cells
What is called when sperm are released from the Sertoli cells
Spermiation
What does the head of sperm contain
Acrosome
What is in Acrosome
Enzyme (hyalurondinase and proteases) that help the sperm penetrate the 2nd oocyte
What does the tail of sperm contain
Flagellum used for locomotion
Mitochondria that form ATP for locomotion
how many sperm are produced a day and how long can it live after being ejaculated?
300 million per day, once ejaculated, 48 hours within the female reproductive tract
what is the secondary male sex characteristics
Sexual behavior and libido Male metabolism (bone and muscle mass heavier) Deepening of the voice
Definition of oogenesis
formation of gametes on the ovaries
Begins in females BEFORE birth
What migrate from yolk sac to ovaries
Primordial germ cells
What primordial germ cells differentiate
into oogonia/oogonium (singular) (Diploid 2n)
produce millions of germ cells mitotically
most degenerate by Atresia before birth
What is the degenerating process of primary oocyte and germ cells
Atresia
At birth 200,000-2,000,000 primary oocytes in each ovary,
at puberty 40,000
mature and ovulate 400
What is surrounding single layer of follicular cells
Primordial follicles
what surrounds primordial follicle and what does it contain
Ovarian cortex and contains collagen and fibres and stromal cells (fibroblast - like)
what does Sertoli cell sdo
Form blood testis barrier
support developing sperm cells
produce fluid and control release of sperm into lumen
Secrete inhibin which slows sperm production by inhibiting FSH
what leydig cells secrete
testosterone in between tubles
sequence of spermatogenesis
Primordial germ cells -> spermatogonia - (mitosis) -> primary spermatocytes -(meiosis I) at puberty -> secondary spermatocytes -(meiosis II) -> spermatids - (Spermiogenesis) -> Sperm (spermatozoon)
Gonadotropin releasing hormone stimulate what to secrete what
Anterior pituitary gland to secretion follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)
What does Luteinizing hormone do
Assists permatogenesis and stimulates leydig cells to production of testosterone
What does Follicle stimulating hormone do
with testosterone, stimulates Sertoli cell to secrete Androgen binding protein to keep hormones level high for spermatogenesis
Which hormone stimulates final steps of spermatogenesis
Testosterone
Testosterone is produced by
Leydig cells
Too much testosterone will inhibit LH to self regulate
Inhibin is secreted by
Sustentacular (Sertoli) cell
Inhibit FSH
Reproductive system ducts in Testes
Seminiferous tubules - > straight tubules -> rete testis -> efferent ducts -> ductus epididymis
Histology of a Graafian Follicle
What is clear area between oocyte and granulosa cells
Zona pellucida
What is granulosa cells attached to zona pellucida
Corona radiata
Formed by granulosa cells secreting follicular fluid
Antrum
What stage oocyte has reached before secondary oocyte
Metaphase of meiosis II and stops
what Theca interna cells secrete
estrogen
What is the theca externa
Outer layer of stromal cells and collagen fibers
What does FSH in female initiate
Growth of follicles
What secretes estrogen
Follicles
What does Luteinizing hormone in female initiate
Ovulation and promotes formation of the corpus luteum
What does corpus luteum secrete
Estrogen, progesterone, relaxin and inhibin
What does Estrogen do
Promote development and maintenance of female reproductive structures, female secondary sex characteristics and breasts
Increase protein anabolism
Lower blood cholesterol
Moderate levels inhibit release of GnRH, FSH and LH (Follicular phase)
High level will promote GnRH and LH to trigger ovulation (Luteal phase)
What does Progesterone do
Works with estrogens to prepare endometrium for implantation
prepares mammary glands to secrete milk
Inhibits release of GnRH and LH
What does relaxin do
Inhibits contractions of uterine smooth muscles
During labor, increases flexibility of pubic symphysis and dilates uterine cervix
What does inhibin do
Inhibits release of FSH and to a lesser extent LH
