Reproductive System

Where does mitosis occur?

Somatic cells

Function of mitosis

growth and repair

Mitosis starts with _________ → ends with _______________

one cell (2n), 2 identical daughter cells (2n)

Where does meiosis occur?

gametes (ova and sperm)

Function of meiosis

reproduction

Meiosis starts with _______________ → _____________ after one meiosis I → ____________ after meiosis II

one diploid germ cell (2n), 2 haploid cells (n), 4 haploid cells (n)

2 reasons why the 4 daughter cells of meiosis are distinct

1. Crossing over

2. Random assortment

Crossing over

allows for small pieces of one chromosome to switch with another chromosome during prophase I

Random assortment

many assortments that the chromosomes could line up in during metaphase I

Where does male gamete production take place?

Takes place inside of the seminiferous tubules of the testes

3 types of cells in the seminiferous tubules

1. Spermatogenic cells

2. Sertoli cells (sustentacular cells)

3. Leydig cells (interstitial cells)

Sertoli cells

cells that provide nutrients and protection for the formation of sperm; form tight junctions to form the blood-testes barrier

Blood-testes barrier function

Blood-testes barrier ensures that developing sperm are not recognized as pathogens

Leydig cells

located just outside the seminiferous tubules and is involved in the secretion of testosterone

Spermatogenesis

Creation of spermatids from spermatogonia

In what direction does spermatogenesis move?

Spermatogenesis moves from the basement membrane towards the lumen of the seminiferous tubule

Spermatogenesis process

spermatogonia (2n) → primary spermatocyte (2n) → secondary spermatocyte (n) → spermatid (n)

Spermatogonia

stem cells that lead to the formation of sperm cells that differentiate into a primary spermatocyte

Are spermatogonia diploid or haploid?

Diploid

Primary spermatocytes

goes through meiosis I to produce 2 secondary spermatocytes

Are primary spermatocytes diploid or haploid?

Diploid

Secondary spermatocytes

undergoes meiosis II to produce 4 spermatids

Are secondary spermatocytes diploid or haploid?

Diploid

Are spermatids diploid or haploid?

Haploid

How are spermatids connected?

Cytoplasmic bridge

Spermiogenesis

formation of mature sperm (spermatozoa) near the lumen of the seminiferous tubule

2 spermatozoa structures

1. Head with acrosome that contains enzymes that allow the sperm to pierce through and fertilize the egg

2. Tail

Oogenesis process

oogonium (2n) → primary oocyte (2n) → secondary oocyte (n) and polar body → ovum (n) and polar body

Where does oogenesis take place?

Ovaries

Ovarian follicle

contains the oocyte that will go through various stages of development

Oogonia

stem cells that lead to the formation of ova cells that differentiate into a primary oocytes (2n)

When do oogonia differentiate?

During fetal development

What occurs to primary oocytes during fetal development

primary oocytes (2n) start meiosis I and arrest in prophase I until puberty

What happens to primary oocytes during puberty?

 primary oocytes (2n) will resume and complete meiosis I to produce a secondary oocyte (n) and a polar body

What occurs to the polar body after it is formed?

The polar body disintegrates after it is formed

What occurs to the secondary oocyte during puberty?

Secondary oocyte undergoes meiosis II and arrests at metaphase II

What event occurs after the secondary oocyte is formed?

Ovulation

What happens after ovulation if fertilization occurs?

the secondary oocyte will undergo meiosis II to create the ovum and a second polar body

What happens after ovulation if fertilization does not occur?

If fertilization does not occur, menstruation occurs and the process restarts

Gonadotropin-releasing hormone hormone (gnRH) is released by the ___________ and acts on the _____________

hypothalamus, anterior pituitary

gnRH function

Leads to release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

FSH affect in males

acts synergistically with testosterone to stimulate androgen-binding protein (ABP)

LH function in males

stimulates secretion of testosterone by Leydig cells

Testosterone function

stimulates final steps of spermatogenesis

ABP function

keeps concentration of the testosterone high

How is testosterone regulated?

Uses negative feedback to regulate itself

Inhibin function in males

Inhibits FSH → inhibits ABP → inhibits testosterone → slows spermatogenesis

What structure secretes inhibin in males?

Secreted by the Sertoli cells of the testes

FSH function in females

triggers the process follicle maturation up to ovulation

Follicle maturation process

Primordial follicle → primary follicle → secondary follicle → Graafian follicle (mature follicle) → corpus luteum

Where is the Graafian follicle located?

Near the periphery of the ovary

Corpus luteum main function

Releases progesterone

Corpus albicans

White scar tissue

What conditions allow for corpus albicans formation

If fertilization does not occur, corpus luteum becomes corpus albicans

Progesterone function

makes the uterus (particularly the endometrium) habitable for the implantation of the zygote

What structure(s) produce(s) progesterone?

Corpus luteum

LH function in females

triggers the process of ovulation

Key event of ovulation

 Graafian follicle ruptures

Estrogen function

contributes to the development of the primary and secondary sex structures

What structure(s) secrete(s) estrogen?

Follicle and corpus luteum

Relaxin function

relaxes the smooth muscle of the uterus (allowing the zygote to implant)

What structure(s) secrete(s) relaxin?

Corpus luteum

Inhibin function in females

 inhibits FSH

What structure(s) secrete(s) inhibin?

Follicle and corpus luteum

When does inhibin release increase?

increases when the corpus albicans

Primordial follicle (when is it found and what does it contain)?

found during fetal development - contain oogonia and primary oocyte that has arrested at meiosis I

Follicular maturation from puberty until menopause

 primary follicle turns into a secondary follicle - has primary oocyte that has arrested at metaphase II

Layers of uterus (outer to inner)

1. Stratum functionalis

2. Stratum basalis

3. Myometrium

Stratum functionalis

 layer of the uterus that sheds during menstruation and where the zygote implants during pregnancy

Stratum basalis

basal layer of the endometrial

Myometrium

Uterine layer made of muscle tissue

2 phases of female reproductive cycle

1. Follicular phase (ovarian cycle)

2. Luteal phase (uterine cycle)

What characterizes the follicular phase/ovarian cycle?

characterized by maturation of the follicle

What characterizes the luteal phase/uterine cycle?

characterized by secretions from the corpus luteum

What event separates the 2 phases of the female reproductive cycle?

Ovulation

Menstrual phase occurs from days ___ to ____ of the female reproductive cycle

0-4

Menstrual phase

shedding of the stratum functionalis, leaving stratum basalis layer

What occurs on day 10 of the female reproductive cycle?

mature follicle is ready for maturation

What is the dominant gonadotropic hormone during the follicularphase?

FSH

Which hormone increases during the follicular phase?

Estrogen

What occurs hormonally right before ovulation?

there is a surge of LH caused by increased estrogen that triggers ovulation

Ovulation occurs on day ____ of the female reproductive cycle

14

Follicular development during ovulation

Graafian follicle → corpus hemorrhagicum → corpus luteum

Most active and second most active hormone during the luteal phase

Progesterone is the dominant hormone during the luteal phase, and estrogen is also moderately active

Proliferative phase

while ovulation is occurring and slightly after ovulation, endometrium is beginning to grow another stratum functionalis layer

What happens to estrogen and progesterone throughout the luteal phase and why?

Estrogen and progesterone inhibit FSH and LH, so they decrease drastically during the luteal phase

Secretory phase occurs from days ___ to ____ of the female reproductive cycle

17-24

Secretory phase of the female reproductive cycle

estrogen and progesterone prepare the uterus for implantation (lots of glycogen secretion)

What occurs about 8 days after fertilization?

the embryo secretes human chorionic gonadotropin (hCG), which causes the corpus luteum to secrete estrogen and progesterone, inhibiting FSH and LH

What occurs at the end of the luteal phase if fertilization does not occur?

Corpus albicans cause estrogen, progesterone, inhibin, and relaxin, allowing FSH and LH to be produced, restarting the process