Biology 11: Sex Organs & Development

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Primary sex organs

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Produce gametes (make sperm, make eggs)

Male: Testis

Female: ovary

(everything else is an accessory sex organ)

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Scrotum

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Suspends testes outside the body cavity

-Sperm needs to be slightly cooler than body temp which is why they lie outside

-Have muscles that bring testis closer to body when environment is cold and relax muscles when its hot

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What do sperm need to have maximum viability?

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1. Really high testosterone levels

2. Be slightly cooler than body temp

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The Testes: function

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1. Make sperm

2. Make androgens (testosterone)

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Seminiferous tubule diagram (composition)

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Sustentacular cells

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Line the seminferous tubule

-Sustain sperm development

-Secrete nutrients such as glucose and ABP (androgen binding protein)

--helps concentrate testosterone near sperm (testosterone levels much ↑ in testes than blood)

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Spermatogonia

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Immature sperm cells

Found in the seminiferous tubule; in b/w the sustentacular cells

-Still diploid cells

-They well have to go through meiosis and become mature sperm cells, and then migrate towards the center of tubule

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FSH

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Stimulates sustentacular cells and spermatogonia

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Interstitial cells

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Makes testosterone

-Aka liatic cells

-Stimulated by hormone LH (litic cells)

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Spermatogenesis Steps:

(occurs daily from puberty to death and unlimited amount of precursor - spermatogonium)

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Front 11

At what point do cells become haploid during spermatogenesis

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Front 12

How many cells are produced from 1 precursor spermatogonium?

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Front 13

A primary spermatocyte is a _______ cell

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1˚ spermatocyte is diploid cell. It will undergo meiosis to form two haploid 2˚ spermatocytes

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In what structure to sperm cells gain ability to "swim"

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Vas Deferens

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Vasectomy

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Front 17

Where is semen produced?

Semen = nutritious (fructose), alkaline fluid

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a.) Seminal vesicles (60%)

b.) Prostate (35%)

--includes "clotting factor" allows semen to coagulate for short term after ejaculation

c.) Bulbourethral glands (4%)

--secrete alkaline mucus on arousal (lubricate urethra, neutralize any remaining acid, since urethra also carries urine)

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Back 18

-Process for making semen not affected by vasectomy

-Prostate is around urethra, which is why older men have difficulty urinating when its enlarged

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Male Sexual function (in terms of sym/ para NS)

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Female Sexual function (in terms of sym/ para NS)

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1. Arousal: parasympathetic control

--erection: dilate erectile arteries

--lubrication: activate greater vestibular glands

2. Orgasm: sympathetic control

-reflexive rthymic contractions of vagina, uterus, fallopian tubes, pelvic floor.

3. Resolution: sympathetic control

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Fetus is originally gender neutral, genetic code then dictates the formation of this in male fetuses

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Wolffian ducts

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Fetus is originally gender neutral, female fetuses then develop:

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Mullerian ducts

-"default" duct. Males secret testosterone which triggers development of wolffian ducts. And secretes MIF (Mullerian inhibiting factor) for regression of mullerian ducts.

No such process for females, just absence of male trigger (Y)

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Female external genitalia

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labia: skin folds that enclose openings

--vaginal and urethral opening (vestibule)

--greater vestibular glands (like bulbourethral glands) secrete lubricant (basic)

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Feature of vagina

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Aka birth canal

-muscular, stretchy

-Acidic

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Cervix features (fertile vs non fertile days)

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Opening to uterus

1. Non-fertile days: (most days of the month). It is closed. Covered with thick, sticky, acidic mucus

2. Fertile days: (only a few days of the month). It dilates. Thin, watery, alkaline mucus.

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Uterus features

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Pregnancy develops here ("-metrium" = uterus) Has two layers:

Endometrium

--Built up and shed off monthly

--Fertilized egg implants here

Myometrium

--smooth muscle wall

--mature muscle cells retain their ability to divide (unique)

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Myometrium

Back 27

Layer of uterus

-smooth muscle wall

-cells retain their ability to divide. Uterus must undergo HUGE size change, this can not be accomplished by simply stretching cells. Must make more cells

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Uterine tubes

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Aka fallopian tube

-pathway for egg to uterus

-ciliated cells (movement down towards uterus)

-this is where fertilization occurs

-tubule ligation here

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Vestibule

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Vaginal opening and urethral opening

-Labia majora/ minora

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Female primary sex organ and functions

Back 30

The Ovary

1. Make eggs (ova)

2. Make estrogen and progesterone

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Menarche

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First menstrual cycle

-Different from puberty which usually starts a few years before.

-(last cycle called menopause)

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What happens after primary ooctye undergoes meiosis.

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Meiosis I → divides into:

1. Seconday oocyte: virtually all cytoplasm/ organelles and 50% DNA

2. First polar body: virtually no cytoplasm and 50% DNA

If fertilized, 2˚ oocyte will go through meiosis II

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Oogenesis Stages:

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Front 34

Organs and hormone signaling pathway involved with menstrual and ovarian cycle

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Front 35

Structures of follicle

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Front 36

Which layer of the follicle produces hormones?

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Thecal cells

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What are the three stages of the ovarian cycle?

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1. Follicular Phase (Day 1-13) 1st day of period

2. Ovulation (Day 14)

3. Luteal Phase (15-28)

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What happens in the follicular phase?

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Event: Build follicle

Triggered by: FSH (follicle stimulating hormone)

Secretes: estrogen

(1st stage of ovarian cycle, then comes ovarian and luteal cycle)

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What happens during ovulation

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Day 14 of ovarian cycle

Event: Oocyte is released

Triggered by: LH

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What is the final stage of the ovarian cycle?

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Luteal Phase (day 15-28)

Formation of corpus luteum

Triggered by surge in LH (which sustains luteum)

-Luteum secretes estrogen + progesterone

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What are the stages of the menstrual/uterine cycle

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1. Menstruation (days 1-5)

--low estrogen/ progesterone

--old endometrium is shed off

2. Proliferative Phase (days 6-14)

--rising levels of estrogen

--rebuild endometrium

3. Secretory Phase (days 15-28)

--stable estrogen and progesterone

--Enhance/maintain endometrium (increase blood supply & glycogen)

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What happens during each of the phases of the uterine cycle?

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Front 43

Where does fertilization occur?

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In the uterine tubes (connects ovary and uterus)

--fertilized egg then implants itself in endometrium (uterus)

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What if egg is fertilized, what hormone is produced?

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hCG (only produced when embryo present)

-equivalent to LH, its as though LH surge did not fall. So the corpus leteum will not degenerate (possible get bigger)

-C.L sticks around, then progesterone/estrogen levels stay high, so there is no fall in levels of endometrium

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Menstrual cycle summary chart

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Estrogen and progesterone have a negative feedback on LH and FSH

-LH surge => formation of corpus luteum (which secretes estrogen + progesterone)

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Back 47

How B.C works:

-keeps estrogen and progesterone levels high

-prevent LH surge, prevent formation of the follicle and subsequent ovulation

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Front 49

Zona pellucida

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A thick, transparent coating rich in glycoproteins that surrounds an oocyte

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Acrosome

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Region at the head of a sperm cell that contains digestive enzymes which, when released during the acrosome rxn, can facilitate penetration of the corona radiata of the oocyte

(takes actions of many sperms cells to release enzymes to digest a pathway)

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Corona Radiata

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The layer of granulosa cells that surround an oocyte after its been ovulated

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Granulosa cells

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The majority of the cells surrounding an oocyte in a follicle. They secrete estrogen during the follicular phase of the ovarian cycle

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How does the ovum prevent polyspermy

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1. Fast block:

-egg deplolarizes

2. Slow block

-cortical reaction (happens near cortex/outer edges of egg) an increase in intracellular Ca2+ and hardening of zona pellucia, ad separates from egg surface.

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Dikaryon

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Cell with two nucleus

-Ex. Ovum when first penetrated by sperm (ooctye has not yet undergone Meiosis II at this point)

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Syngamy

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Fusion of egg and sperm nuclei

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Trophoblast

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Outer layer of blastula

-secretes hCG

-becomes the placenta (after 3 months)

---takes over hormone secretion, levels of hCG drop (b/c hCG maintains corpus leteum but placenta secretes hormones which means c.l. is not needed -secrete estrogen/progesterone to not lose lining)

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Where are embryonic stem cells taken from?

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Blastula => pluripotent stems cells = can becomes ANY of the body cells but NOT the placenta

--induced pluripotent stem cells are reveresed engineered adult stems cells to be similar to embryonic stem cells

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Difference b/w determination and differentiation

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Determination = cytoplasmic changes, no physical changes

Differentiation = physical changes into new cell types

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Determination of stem cells

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Cytoplasmic changes toward new cell type. No physical changes

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Multipotent cells

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Adult stem cells

-Can become some, but not all, of the cell types in the body

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Example of a totipotent cells

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ONLY cell that is totipotent = zygote

-can become any cell in the body AND the placenta

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Gastrulation

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What changes does the baby experience after birth?

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1. Close lung bypass, and close liver bypass

2. Close umbilical vessels

3. Stop making fetal hemoglobin

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What changes does the mother experience after birth?

Back 65

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