Ch. 46 Male and Female Animal Repro Systems

Land animal evolution breakthroughs

Amniotic egg - freed reptiles of need to return to water, internal fertilization

Amniotic egg

Can do gas exchange w/o drying out. 

Amnion – top left, prevents drying 

Allantois – top right, holds wastes and provides oxygen

Yolk sac – below, nutrients to yolk  

Chorion – around, surrounds the above 3 

Fertilized, multicellular, very complex. We could call it an ovum

cloaca

Opening for digestive, repro and excretory (uric acid in birds) system

Mammalian embryos are

viviparous

Viviparous

develop within the female reproductive tract

Viviparous mammalian embryos

Include marsupials and eutherians

marsupials

Complete development in pouch, nourish w/ milk 

eutherians

Placental nourishment w/in uterus, nourished w/ milk after birth

Male repro tract structures

testes, seminiferous tubules, epididymis, vas deferens, seminal vesicle, prostate and Cowper's glands, urethra, penis

testes

produce sperm cells and testosterone

seminiferous tubules

produce immature sperm cells

epididymis

matures and stores sperm cells in coiled duct

vas deferens

duct that carries sperm from epididymis to urethra

seminal vescicle

secretes fructose into semen as food for sperm

prostate

secretes alkaline buffer to semen to protect sperm from acidic environment of vagina

Cowpers glands

secretes mucus into semen to protect sperm from acidity in urethra

urethra

a tube that carries urine and semen out of the body

penis

delivers sperm to the female reproductive tract and expels urine

sperm parts

head, midpiece, tail

sperm head

nucleus and acrosome – vesicle w/ digestive enzymes to get through egg

sperm midpiece

full of mitochondria for tail energy. Sperm swim in their own food (O2 and fructose) to power cell resp/ATP production

sperm tail

move sperm to egg

exocrine

male repro glands are all _____. All push material to the outside

Gametogenesis

gamete development. Can be spermatogenesis or oogenesis

spermatogenesis

Division of spermatogonium into haploid differentiated spermatozoa that can all be used. Mitosis and 2 meioses. Spermatogenesis depends on the pulsatility of GnRH secretion

oogenesis

Division of oogonium into one haploid ovum and 3 haploid polar bodies that cannot be used. Mitosis and 2 meioses.

seminiferous tubules

Site of sperm production and spermatogenesis in testes

Sertoli cells

w/in seminiferous tubules, support sperm development

Leydig cells

outside seminiferous tubules, produce testosterone

hormones involved

GnRH, FSH, LH 

GnRH

Gonadotropin-releasing hormone - stimulates release of gonadotropins

FSH

Follicle-stimulating hormone - stimulates growth of ovarian follicles in females and sperm production in males

LH

Luteinizing hormone - triggers ovulation in females and stimulates testosterone production in males

Testosterone

promotes spermatogenesis through the release of these hormones. Promotes development of sex characteristics. Inhibits GnRH and LH in a negative feedback loop of its own production

pulsatile

As a result of the negative feedback loop, testosterone, LH, and GnRH are all

female repro tract structures

ovary, oviduct (fallopian tube), uterus, cervix, vagina, clitoris

ovary

site of oocyte storage and development

oviduct/fallopian tube

transports oocyte from ovary to uterus. Site of fertilization

uterus

lined by endometrium. hollow chamber in which embryo develops

cervix

base of uterus that opens into vagina

vagina

sex organ that produces lubricants, birth canal

clitoris

sexual arousal organ

Fertilization occurs in the

fallopian tubes

ovary structures

Potential ovum, follicle, antrum, Graafian follicles, corpus luteum, ovum, liberated ovum is ovulation

Potential ovum/egg cells

stimulated by hormones to develop. Once they do, cells around them will start to appear.

follicle

grows bigger and bigger around the egg (also big)

antrum

in mature follicle. Chamber that inflates with fluid. The egg is now surrounded by cells and so are the follicles. Once the antrum is full it bursts and releases egg (ovulation).

Graafian follicles

Mature follicles

corpus luteum

Once the follicle bursts, what’s left is the corpus luteum that still makes hormones, shrinks, and scars eventually

ovum

The female reproductive cell or egg produced by the ovaries, which can be fertilized by sperm.

ovulation

liberated ovum. Involves mitosis, through cleavage. Mitosis without growth. Much smaller than the egg and zygote. They get smaller with every division.

oogenesis

Ovary w/ sequential development. Results in a big cell and a little one that dies off. 2nd division doesn't occur until after fertilization. Meiosis is the same but at each of them only 1 cell is destined to become an ovum/egg cell. 1^st division: unequal cytokinesis, one becomes a polar body and will die. Same for 2^nd division. Eggs are big. Bigger than the normal cell. Oogenesis results in a big cell and a little one that dies off. 2nd division doesn't occur until after fertilization.  

morula

solid ball of cells (totipotent)

blastocyst

ball of 100 clearly divided cells (totipotent).

blastula

future embryo and placenta (some differentiation already – pluripotent, not multipotent yet)

hormones involved

GnRH, FSH, LH, estradiol, progesterone

GnRH

tropic hormone secreted by neurosecretory cells of the hypothalamus

Gonadotropins

stimulate the release of ovarian hormones (estradiol and progesterone). FSH and LH.

estradiol

form of estrogen produced by the ovaries that regulates the menstrual cycle

progesterone

steroid hormone produced by the ovaries that regulates the menstrual cycle and maintains pregnancy

tropic hormones

Remember tropic hormones stimulate the release of other hormones. 

GnRH is tropic and released by hypothalamus 

Hormones in context of ovulation in ovaries

notice specific spikes / characteristics. Be able to tell which line is which hormone. Could think of order as ELFP. Estrogen before ovulation, LH and F high and low during, progesterone after.

Hormones in context of uterus

Secreted in different amounts throughout menstrual cycle to trigger other hormones

estrogen

Estrogen is a steroid – a lipid – hydrophobic – intracellular receptor. Binds in cytoplasm and sends signal directly to DNA in the nucleus. Directly influences gene regulation/expression. 

pregnancy

carrying one or more developing embryos or fetuses in the uterus

sperm path

(Male) testis→epididymis→vas deferens→urethra/penis→(Female) vagina→uterus→Fallopian tube // FERTILIZATION

zygote path

(Fallopian tube→uterus) divides/cleavage→blastula(100-ish cells) implants in endometrium of uterus→embryo and placenta develop→birth

twins form when

Identical are monozygotic, one zygote splits into two genetically identical cells, share placenta 

Fraternal are dizygotic, two eggs fertilized by two separate sperm, genetically distinct but develop at same time, separate placentas 

endometriosis

Cells of the uterine lining migrate to an ectopic location

menopause

Repro tract aging. Ovulation and menstruation stops. Ovaries no longer sensitive to FSH and LH

Where everything occurs in the repro tract 

Ovulation, fertilization, cleavage, implantation. Cleavage is mitosis without growth 

ectopic pregnancy

embryo implants in the wrong place - cervix or fallopian tubes. Not survivable for the embryo.

placental circulation

for transport of nutrients, gasses and wastes by both passive and active transport b/t cap beds

contraception

Deliberate prevention of pregnancy

surgical

vasectomy (M) tubal ligation (F)

vasectomy

vas deferens are tied and cut

tubal ligation

fallopian tubes are tied and cut, cauterized, or banded

in vitro fertilization

a medical procedure where an egg is fertilized by sperm outside the body