Reproduction

Question 1

Great diversity of reproductive traits–

Answer 1

seasonality, gestation times, organ

morphology, sperm behavior

Question 2

Mammalian reproductive traits must be

ancient

Answer 2

– Mammary glands and milk
– Close mother-young bond
– Viviparity

Question 3

Female Anatomy

• Monotreme tract

Answer 3

– Right and left uteri
enter urogenital
sinus
– Cloaca present

Question 4

Female Anatomy

• Metatherians

Answer 4

– Pair	of	uteri	enter	into	
vaginal	sinus
– Two	cervix	(duplex)
– Two	vaginas
– Common	urogenital	
sinus
– Birth	occurs	through	
pseudovaginal	canal

Question 5

Female Anatomy

• Eutherians

Answer 5

– Paired	functional	
ovaries
– May	retain	paired	
cervix	and	uteri	
(duplex)	or	uteri	may	
be	fused	(simplex	or	
bicornuate)
– Single	vagina

Question 6

Three basic categories of female

reproductive systems

Answer 6

• Induced ovulation (rabbits, camelids)
• Estrous cycle (carnivorans, rodents)
• Menstrual cycle (many primates, some
pteropidids)

Question 7

Estrous cycle vs. menstrual cycle

Answer 7

• Sexual activity concentrated vs. diffuse
• If no fertilization, endometrium is re-absorbed
vs. shed
• Estrous females advertise, menstrual females
hide

Question 8

Estrous Cycle

Answer 8

• Proestrus:	Ovarian	follicle	grows,	
uterine	lining	develops
• Estrus:	Female	is	sexually	
receptive,	follicle	matures,	
ovulation	happens
• Metestrus/Diestrus:	Corpus	
luteum forms	from	ruptured	
follicle	and	prepares	
endometrium for	implantation,	
but	if	no	fertilization,	it	regresses	
• Anestrus:	cycle	rests	before	
restarting

Question 9

Embryonic	Development
• Fertilization	occurs	in	
• Zygote	begins	cleavage	
• Blastocyst reaches	uterus	in	
• Outer	layer	(trophoblast)
invades	the	
• Trophoblast forms	
• Inner	cell	mass	forms

Answer 9

• oviducts
• divisions
• 3– 4 days
• endometrium
• placenta
• embryo

Question 10

Placenta
• Functional connection between
• Allows for nutritional, respiratory, and
• Functions also as a __ for large molecules
and bacteria
• Placentas vary in ___ and ___ of villi
• Degree of __ between fetal and maternal
bloodstreams also varies

Answer 10

• fetus	and	mother
• 	excretory	
exchange
• 	barrier	
• shape	and	extent	
• 	separation

Question 11

Eutherian Parturition
• Rising estrogen levels and declining
progesterone levels results in:

Answer 11

– Rhythmic, powerful contractions of uterus
– Softening of cervix
• At birth, fetal part of placenta is expelled

Question 12

Lactation: synthesis and secretion
• Lactation, suckling, and diphyodonty may have
evolved
• Mammary glands undergo considerable
growth during pregnancy
• Milk production is stimulated and regulated by

Answer 12

• together
• due	to	hormonal	
influence
• 	stimulated	by	suckling	and	
regulated	by	prolactin

Question 13

Lactation

• Milk composition

Answer 13

– Eutherians—remains fairly uniform
– Metatherians—changes during lactation
– Varies little among marsupial species at similar
stages in lactation, but in placental mammals, the
concentration of milk varies by species

Question 14

Reproductive organ variation

Answer 14

• Penises
– Some	w/	baculum (carnivorans,	rodents,	shrews,	
primates,	bats)
– Some	retractable
– Big	or	small
• Testicles
– Abdominal	or	scrotal	position
– Seasonally	abdominal/scrotal	or	permanent
– Big	or	small

Question 15

Mating systems and sperm
competition
• Promiscuity

• Polygyny mediated by combat
• Monogamy

Answer 15

– Large testes

– Small testes

– Small testes

Question 16

Sperm competition in promiscuous

species

Answer 16

• He who hath the most, fastest sperm wins
• Sperm trains
• Kamikaze sperm
• Mating plugs

Question 17

Diversity	of	reproductive	systems	in	
mammals
• Females	have:
• Males	have:
• Both	sexes:

Answer 17

• Females	have:
– Different	types	of	placentas
– Different	types	of	estrous	cycles
– Different	reproductive	schedules
• Males	have:
– Testis	sizes	correlated	with	mating	system
– Cooperating	sperm
– Possibly	defensive	sperm
• Both	sexes:
– Probably	manipulate	the	other	w/	physical	and	
chemical	cues