Repro Study Guide

Question 1

What does an ovarian follicle consist of

Answer 1

an oocyte surrounded by follicle cells (or granulosa cells) which support the oocyte

Question 2

What are the different type of ovarian follicles that form in the ovary?

Answer 2

• Primordial Follicle
• Primary Follicle
• Secondary Follicle
• Vesicular Follicle

Question 3

Primordial Follicle

Answer 3

• Most primitive type of ovarian Follicle
• Primary oocyte and single flattened layer of follicle cells
• Primary oocytes is arrested in meiotic prophase
• 1.5 million present at birth

Question 4

Primary Follcile

Answer 4

• primary oocyte with layers of follicular cells
• granulosa cells secrete estrogen which stimulates changes in the uterine lining
• thecal cells on periphery follicle which control follicle development
• thecal cells secrete androgen which is converted to estrogen by granulosa cells.

Question 5

Secondary Follicle

Answer 5

• Primary oocytes with multiple layers of granulosa cells
• forced to one side of the follicle by fluid space called antrum
• the antrum increases in size as ovulation nears.
• the oocyte is forced toward one side of the follicle where it is surround by a cluster of follicle cells termed the cumulus oophorus
• Surrounding the primary oocyte are two protective structures, the zone pellucida and the corona radiata

Question 6

zona pellucida

Answer 6

the translucient structure that contains glycoproteins

Question 7

corona radiata

Answer 7

innermost layer of the cumulus oophorus cells

Question 8

Vesicular follicle

Answer 8

(mature follicle) -contains secondary oocyte

• arrested in metaphase II
• surrounded by zone pellucida and corona radiata, granulosa cells, and the fluid-filled antrum
• usually one formed per month

Question 9

Overview of ovulation

Answer 9

• the mature follicle ruptures and an oocyte (in metaphase II) is expelled
• the remnants of the follicle in the overy turn into the corpus luteum
• the corpus luteum secretes the sex hormones progesterone and estrogen
• these stimulate the buildup of the uterine lining and prepare the uterus for possible implanation of a fertilized oocyte
• when the corpeus luteum undergoes regression it turns into a white connective tissue scar called the corpeus albicans

Question 10

Oogenesis

Answer 10

• the formation of an ovum

Question 11

Oogenesis before birth

Answer 11

• Oogonia divide by mitosis to produce primary oocytes
• Primary Oocytes start meiosis but stop in prophase I
• The primary oocyte in the primordial follicle remains arrested in prophase I until after puberty

Question 12

Oogenesis during childhood

Answer 12

• A female’s ovaries are inactive and no follicles develop
• atresia occurs

Question 13

atresia

Answer 13

some primordial follicles regress

Question 14

Oogenesis from puberty to menopause

Answer 14

• up to 20 primordial follicles mature into primary follicles every month.
• Some mature into secondary follicles.
• Those that do not mature go through atresia
• One secondary follicle matures into a vesicular follicle, the primary oocytes completes the first meiotic division to produce a polar body and a secondary oocyte (haploid cell) that is arrested in the second meiotic metaphase
• if the secondary oocyte is fertilized - it will complete the second meiotic division and becomes an ovum. If it is not fertilized it will degenerate

Question 15

Myometrium

Answer 15

formed from three layers of smooth muscle

Question 16

Endometrium

Answer 16

• Simple columnar epithelium and underlying lamina propina
• lamina propina- filled with uterine glands which enlarge during the cycle
• deeper basal layer immediately adjacent to myometrium, contains stem cells
• superficial functinoal layer begins monthly growth under influence of estrogen and progesterone.
• shed as menses

Question 17

What are the phases of the ovarian cycle?

Answer 17

Follicular Phase

Ovulation

Luteal Phase

Question 18

Follicular phase of the ovarian cycle

Answer 18

• occurs during days 1-13
• 20 primordial follicles are stimulated to mature into primary follicles by LH and FSH
• as the follicle develops, their follicular cells release the hormone INHIBIN which helps to inhibit FSH production
• thus preventing excess ovarian follicle development and allowing the current primary follicles to mature
• A few mature in vesicular follicles, while the others undergo atresia
• Usually only one vesicular follicle will mature into a mature follicle under the influence of estrogen
• As the secondary follicle matures into a mature follicle, its primary oocyte finishes meiosis I and two cells form

Question 19

The two cells that form

Answer 19

• one of these receives a minimal amount of cytoplasm and forms a polar body, which is a nonfunctional cell that later regresses
• the other cell receives the bulk of the cytoplasm and becomes the secondary oocyte, which continues to develop and reach metaphase II of meoisis before it is arrested again.
• doesn’t complete meiosis II until it is fertilized by a sperm
• if not fertilized it breaks down and regresses about 24 hours laer

Question 20

Ovulation phase of ovarian cycle

Answer 20

Occurs on day 14

• release of secondary oocyte from vesicular follicle due to peak in LH secretion
• as the time of ovulation approaches, the follicle cells in the mature follicle increase their rate of fluid secretion, forming a larger antrum and causing further swelling within the follicle
• The edge of the follicle that continues to expand at the ovarian surface becomes quite thin and eventually ruptures, expelling the secondary oocyte

Question 21

Luteal phase of ovarian cycle

Answer 21

Days 15-28

• the remaining follicle cells become corpus luteum due to LH. Secretes progesterone and estrogen that stabilze and buildup the uterine lining, and prepare for possible implanation of a fertilized oocyte
• also secretes inhibin, which will inhibit the hypothalamus and anterior pituitary from secreting their reproductive hormones.
• the corpus luteum has a life span of about 10 to 13 days if the secondary oocyte is not fertilized
• After this time, the corpus luteum regresses and becomes a corpus albicans
• as the corpus luteum regresses, its levels of secreted progesterone and estrogen drop
• causing the uterine lining to be shed in a process called MENSTRUATION
• the shed lining is called menses or a period

Question 22

What are the phases of the uterine cycle

Answer 22

Menstrual phase

Proliferative phase

Secretory Phase

Question 23

Menstrual phase of the uterine cycle

Answer 23

Days 1-5

Sloughing of functional layer and lasts through the period of menstrual bleeding

Question 24

Proliferative phase of the uterine cycle

Answer 24

Days 6-14

Development of new functional layer of endometrium overlaps the time of follicle growth and estrogen secretin by the ovary

Question 25

Secretory Phase of the uterine cycle

Answer 25

Days 15-28

-results in increased vascularization and uterine gland development occurs primarily in response to progesterone secretion from the corpus luteum

Question 26

if fertilization does not occur

Answer 26

the corpus luteum will degenerate and the progesterone level will drop dramatically. Without significant levels of progesterone, the functions layer slough off and the next uterine cycle will begin with the menstrual phase.

Question 27

Spermatogenesis

Answer 27

• The process of sperm development that occurs within the seminiferous tubule of the testis.
• Does not begin until puberty
• when GnRH secreted by the hypothalamus stimulates the anterior pituitary to secrete significant levels of FSH and LH stimulate the testes to begin gamete development
• Spermatogonia undergo mitotic divisions to produce a new germ cell and a committed cell (primary spermatocyte)
• Meiosis I begins in the diploid primary spermatocytes. The haploid cells produced during meiosis I are called secondary spermatocytes
• Meiosis II originates with the secondary spermatocytes and produces haploid spermatids

Question 28

Spermiogenesis

Answer 28

• begins with spermatids and results in morphologic changes needed to form sperm that will be motile -produces 4 sperm
• Final stage of spermatogenesis
• Spermatid becomes mature spermatozoa (sperm)
• The spermatid sheds excess cytoplasm and its nucleus elongates
• A structure called the acrosome cap from over the nucleus. This structure contains digestive enzymes that help penetrate the secondary oocyte for fertilization
• As the spermatid elongates, a tail forms called a flagellum-forms from the microtubules within the cell
• Tail is attached to a midpiece or neck region containing mitochondria and a centriole
• Stay in epididymis for a period to become fully motile

Question 29

Sustentacular cells

Answer 29

• nondividing support cells that surround dividing germ cells continuously producing sperm
• Helps nourish developing sperm
• Secretes androgen binding protein in response to FSH which keeps testosterone levels high in testes
• Rising sperm count levels cause release of the hormone inhibin when sperm count high, which inhibits FSH secretion

Question 30

Interstitial Cells

Answer 30

• produce angrogens (Testosterone) under LH stimulation
• Testosterone stimulates spermatogenesis but inhibits GnRH secretion and reduces the anterior pituitary’s sensitivity to GnRH
• Testosterone also stimulates libido and development of secondary sex characteristics.