Biology of gender Sex chromosomes determine gonadal sex (testis-determining factor)

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1 Indifferent ducts of embryo Y chromosome present Y chromosome absent Male Female penis ovary uterus vagina testis Biology of gender Sex chromosomes determine gonadal sex (testis-determining factor) Phenotypic sex is depends on development of external genitalia w/hormone Differentiation of genitalia depends on whether testosterone is present At 7 weeks Undifferentiated genitalia 1

Intersex individuals experience opposite sex hormones during early

Some examples: Androgen insensitivity Lack of enzyme for testosterone

cortisol, aldosterone. Steroids converted to androgens instead.

from abdomen into scrotum Inguinal area is a common spot for hernias

2 Intersex individuals experience opposite sex hormones during early development or are insensitive to normal hormones. Some examples: Androgen insensitivity Lack of enzyme for testosterone production Congenital adrenal hyperplasia (enzyme missing to produce cortisol, aldosterone. Steroids converted to androgens instead.) Male reproductive anatomy During fetal development, testes move from abdomen into scrotum Inguinal area is a common spot for hernias (intestine pokes through abdominal wall) The scrotum provides a cool area optimal for spermatogenesis 2

Sperm production Epididymis Spermatogenesis: spermatogonia (2N) Seminiferous tubules spermatozoa (N) Lumen of

3 Sperm production Ductus deferens Epididymis The cells of Leydig in testes secrete Seminiferous testosterone (T) tubules T secreted at puberty produces 2 o sex characteristics, spermatogenesis, & maintain tracts Ductus deferens Sperm production Epididymis Spermatogenesis: spermatogonia (2N) Seminiferous tubules spermatozoa (N) Lumen of seminifeous tubule Sertoli cell Spermatids Secondary spermatocyte Primary spermatocyte Sertoli cell Meiosis Spermatogonium Mitosis 3

4 Controlling sperm production Unlike females, males produce sperm from puberty onward Spermatogenesis controlled by LH and FSH LH & FSH in males LH acts on Leydig cells for T prod n FSH acts on Sertoli cells for sperm prod n (inhibin provides negative feedback) 4

intense exercise, stress Tight underwear, pants Environmental pollutants (pesticides, lead, paint,

deferens Making something to swim in Seminal vesicle Ductus deferens Testis Urinary bladder Prostate gland

5 Causes of infertility? Sperm production, viability influenced by: Smoking, marijuana use Alcohol abuse Anabolic steroids, overly intense exercise, stress Tight underwear, pants Environmental pollutants (pesticides, lead, paint, radiation, heavy metals) Sperm storage Spermatids become motile and are stored in epididymis and ductus deferens Making something to swim in Seminal vesicle Ductus deferens Testis Urinary bladder Prostate gland Bulbourethral gland Seminal vesicles supply fructose, prostaglandins for muscle contraction, & fibrinogen Prostate gland secretes alkaline fluid and clotting enzymes Bulbourethral glands add mucus for lubrication 5

physical stimulation positive feedback Ejaculation Dramatic shift to SNS contractions move semen to urethra and out Female

6 Signals for erection and ejaculation Arousal Pudenal nerves carry signals from penis to lower spinal cord & brain Spinal reflex and brain send PNS signals to penile arterioles Arousal causes muscle contractions that incr. physical stimulation positive feedback Ejaculation Dramatic shift to SNS contractions move semen to urethra and out Female reproductive anatomy Ovaries produce estrogen, progesterone, and are site of oogenesis Estrogen: maintenance of the female tracts, 2 o sex characteristics, ova maturation and release 6

Oogenesis overview Oogonia divide mitotically Meiosis I produces a primary oocyte

oocytes on a cyclical basis Ovarian cycle Follicular phase - first half of cycle

uterus is prepared for implantation Follicular Luteal Looking within the ovary

7 Oogenesis overview Oogonia divide mitotically Meiosis I produces a primary oocyte (diploid), surrounded by follicle cells These oocytes develop into secondary oocytes on a cyclical basis Ovarian cycle Follicular phase - first half of cycle when follicles mature and are ovulated Luteal phase - second half of cycle when uterus is prepared for implantation Follicular Luteal Looking within the ovary follicular phase Primary follicle Follicle cells oocyte FSH and LH levels are increasing 7

8 Looking within the ovary follicular phase Follicle cells secrete estrogen Dividing follicular cells Primary oocyte Thecal cells Looking within the ovary follicular phase antrum Antrum collects fluid with estrogen Estrogen inhibits FSH and LH, so FSH Low to moderate levels of estrogen 8

Late follicular phase Follicle (thecal) cells

levels of estrogen Late follicular phase

9 Late follicular phase Follicle (thecal) cells Antrum primary oocyte Follicle (granulosa) cells High estrogen levels promote LH secretion w/ positive feedback loop High levels of estrogen Late follicular phase Mature follicle Antrum Oocyte finishes meiosis I it now is a 2 o oocyte 9

Luteal phase corpus luteum Corpus luteum secretes

Estrogen initiates preparation of endo- and

phase) Progesterone endometrium vascularization,

10 Pop! Ovulation! secondary oocyte Egg is flushed out Follicle remains Luteal phase corpus luteum Corpus luteum secretes progesterone and estrogen Estrogen and progesterone Estrogen initiates preparation of endo- and myometrium, prime uterus for progesterone (follicular phase) Progesterone endometrium vascularization, glycogen, decrease contractions (luteal phase) Progesterone inhibits LH and FSH (this is how birth control pills work) 10

Inhibit LH and FSH, so no ovulation Thicken cervical mucus Thicken uterine lining, inhibiting implantation Morning

11 Birth control pills, patches, rings BCP contain estrogen and progestin (or just progestin if nursing or estrogen-sensitive) They vary in type of progestin and amount of estrogen. Inhibit LH and FSH, so no ovulation Thicken cervical mucus Thicken uterine lining, inhibiting implantation Morning after pills contain a much higher dosage Changes in endometrium If the corpus luteum degenerates, progesterone drops and menstruation occurs Degenerating corpus luteum 11

But if there are sperm around Fertilization normally occurs

help some sperm reach the oviduct acrosome in action Embryo

Fertilization Trophoblast Implants the embryo Ovulation

chorionic gonadotropin Endometrium has glycogen, and becomes

12 But if there are sperm around Fertilization normally occurs within a day of ovulation Contractions of the myometrium help some sperm reach the oviduct acrosome in action Embryo forms before reaching the uterus Blastocyst Cleavage Embryo Fertilization Trophoblast Implants the embryo Ovulation Implantation Settling into the uterus Blastocyst secretes chorionic gonadotropin Endometrium has glycogen, and becomes more vascularized from progesterone 40% of blastocysts never implant 12

Settling into the uterus Trophoblast enzymes digest

Embryo Eventually forms chorion Placenta development

13 Settling into the uterus Trophoblast enzymes digest proteins of the endometrium. This carves a hole for implantation. Endometrium Trophoblast Endometrium Embryo Embryo Embryo Eventually forms chorion Placenta development Placenta = chorion from embryo and uterine lining from mother. These tissues interlock like fingers Projections of chorion have capillaries to form placental villi. They extend into the mother s blood. 13

Placenta development Gasses, wastes, nutrients diffuse bw capillaries of mother and fetus Drugs,

chorionic gonadotropin (hcg) Estrogen Progesterone Fertilization Delivery Question: What are some

The placenta cannot make estrogen or progesterone on its own A placenta can be insufficient to

14 Placenta development Gasses, wastes, nutrients diffuse bw capillaries of mother and fetus Drugs, pollutants, chemicals also diffuse mother s blood Amniotic sac Placental villus Chorion Human chorionic gonadotropin (hcg) Estrogen Progesterone Fertilization Delivery Question: What are some insufficiencies of the feto-placental unit? The placenta cannot make estrogen or progesterone on its own A placenta can be insufficient to support fetal growth due to blood flow problems Hypertension, diabetes, anemia, blood thinners, clotting disorders, smoking. Placental abruption (placenta breaks away) 14

15 Question: How does the body change during pregnancy? movie Getting ready for birth... ACTH and cortisol from the fetus promote prostaglandins, initial contractions occur High levels of estrogen make the uterus more sensitive to oxytocin and initiate gap junctions in myometrium Uterus has mild contractions. Baby s head is down in pelvis Positive feedback with oxytocin Stretching the cervix causes more oxytocin to be released Oxytocin induces stronger contractions 15

16 Lactation 16

Biology of gender Sex chromosomes determine gonadal sex (testis-determining factor)

Indifferent ducts of embryo Biology of gender Sex chromosomes determine gonadal sex (testis-determining factor) Y chromosome present Y chromosome absent Phenotypic sex is depends on development of external