NPB 130: L28 Ovary/testes

Why are gonads special endocrine glands?

Ovary + testes make steroids AND gametes

Sex hormones critical for 3x things

reproduction

-growth

metabolism

What controls reproduction? x3 categories

Steroids

• Androgens (androstenedione, testosterone, dihydrotestosterone)
  • Estrogens (estradiol, estrone, estriol) – follicle development, ovulation
  • Progesterone – uterine environment for early embryo development

Eicosanoids

• Prostaglandins (PGE, PGF2α) – responsible for “killing” or lysing the Corpus luteum

Proteins

• GnRH
  • Pituitary gonadotropins (FSH, LH)
  • Inhibin

HPG axis

Arc parvocellular neuron → GnRH → gonadotropes → FSH + LH

How do male and female GnRH regions develop?

• Male testes: secrete testerone → cross blood-brain barrier → aromatase into E2

  • E2 exposure= desensitize to estrogen later (refractory)

  • No surge center develop (defeminine)

• Female ovary: secrete E2 → binds to aFP (alpha-fetoprotein) → can’t cross blood-brain barrier

  • Surge center develops

LH production in male

M: LH make testerone in cyclic pattern

F: this is covered so idk if need know, but high LH right before preovulatory surges

GnRH release in females… 2 phases

Tonic phase: release GnRH at intervals

Pre-ovulatory GnRH surge: Release when E2 levels high → positive feedback on GnRH to cause ovulation

IDK what this corresponds, but: need time for embryo to develop before ovulate again (after spike)

HPG axis in females + males REGULATION

Kisspeptin neurons in POA + Arc: Receive positive/neg feedback (NOT GnRH neurons)

• → Then stimulate GnRH neurons

• make GnRH → anterior pituitary make FSH/LH

Inhibition:

• FSH/LH neg feedback → ovary/testes → testerone - (CYP19A1)—> estrogen

  • estrogen inhibit kisspeptin

• Progesterone (ovary) inhibit kisspeptin

  • Important to prevent early ovulation while embryo develop

• Inhibin: From ovary/testis: inhibit FSH

HPG axis in females ONLY regulation

Large follicle= estradiol

• Low levels: neg feedback FSH

• High level: positive feedback on kisspeptin in POA —→ GnRH surge

Ovary also make inhibin

Testis anatomy

-where sperm made

seminferous tubule

→ drain into epididymis

Ovary anatomy

-where follicle made

-ovulate where

• follicle made in cortex ovary

• Ovulate in oviduct

Testis cell types

• Leydig cells

• Sertoli cells

• Peritubular myoid cells → contract semiferous tubule make sperm

• Germ cells (sperm)

tunica albuginae: connective tissue protect semiferous tubule

Leydig cells (LC)… what do they respond to?

do?

Respond to LH → cause uptake cholestrol (StAR) → cholestrol

→ make progesterone, DHEA, testerone =ANDORGENS

*pic for pathway memorize

Sertoli cells

-purpose x2

-barrier?

-respond to?

-produce 2 things

-”nurse cell”= nourish + adequate environment germ cell

-help w/ sperm maturation

-has blood testes-barrier

-Respond to FSH → convert androgen → estrogen

• Also testerone + 5-alpha-reductase → Dihydrotesterone

Blood testes barrier

Mitosis → haploid to diploid

Barrier protect haploid (sperm) from human immune system, which doesn’t recognize it

Dihydrotesterone (DHT)

more potent androgen

→used in secondary sexual characteristics

-main form of androgen in males

DHEA

adrenal androgen

• main androgen form in females

• Zona reticularis of adrenal cortex, main androgen in females

• Less potent form

Androgen receptor

DHT has 30x greater affinity for AR

What is main steroid hormone produced by testes

testerone

Male reproductive organs are made from?

DHT