Lecture Biology (7th edition) - Chapter 46: Animal reproduction

After studying this chapter you will be able to: Distinguish between asexual and sexual reproduction; explain how hermaphroditism may be advantageous to animals that have difficulty encountering a member of the opposite sex; describe various ways in which animals may protect developing embryos; using diagrams, identify and state the function of each component of the male and female reproductive systems;...

PowerPoint Lectures for

Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 46

Animal Reproduction

• Overview: Doubling Up for Sexual

Reproduction

which will fertilize

Figure 46.1

• A population transcends finite life spans

• Concept 46.1: Both asexual and sexual

reproduction occur in the animal kingdom

individuals

• Sexual reproduction is the creation of offspring

form a zygote

fission

individuals of approximately the same size

Figure 46.2

• Also common in invertebrates is budding

outgrowths of existing ones

fragmentation, which

some or all of which develop into complete adults

regrowth of lost body parts

• Animals may reproduce exclusively asexually

or sexually

being fertilized

• Among vertebrates, several genera of fishes,

amphibians, and lizards, including whiptail lizards

– Reproduce exclusively by a complex form of

like

Female- like Female-like

like

Male-(a) Both lizards in this photograph are C uniparens

females The one on top is playing the role of

a male Every two or three weeks during the breeding season, individuals switch sex roles.

(b) The sexual behavior of C uniparens is correlated

with the cycle of ovulation mediated by sex hormones.

As blood levels of estrogen rise, the ovaries grow, and the lizard behaves like a female After ovulation, the estrogen level drops abruptly, and the

progesterone level rises; these hormone levels correlate with male behavior.

• Sexual reproduction presents a special

problem for certain organisms

hermaphroditism

female reproductive systems

• Another remarkable reproductive pattern is

sequential hermaphroditism

its lifetime

Figure 46.4

• Concept 46.2: Fertilization depends on

mechanisms that help sperm meet eggs of the same species

egg and sperm

• Some species have external fertilization, in

which

sperm in the external environment

Figure 46.5

Eggs

• Other species have internal fertilization, in

which

reproductive tract, and fertilization occurs within the tract

• In either situation, fertilization requires critical

timing

pheromones, and/or courtship behavior

between male and female animals

environment can handle

• The embryos of many terrestrial animals

environments

develops inside the female

• Many different types of animals

offspring

Figure 46.6

gametes

• The least complex systems

organs that produce gametes in most animals

• The most complex reproductive systems

glands that carry, nourish, and protect the gametes and the developing embryos

• Many animals with relatively simple body plans

Figure 46.7

Male organs: Female organs:

Genital pore

(Excretory pore)

Seminal receptacle

3

Seminal vesicle

3 Uterus

• Most insects

reproductive systems

Figure 46.8a, b

(a) Male honeybee Sperm form in the testes,

pass through the sperm duct (vas deferens), and are stored in the seminal vesicle

The male ejaculates sperm along with fluid from the accessory glands (Males of some species of insects and other arthropods have appendages called claspers that grasp the female during copulation.)

(b) Female honeybee Eggs develop in

the ovaries and then pass through the oviducts and into the vagina A pair of accessory glands (only one is shown) add protective secretions to the eggs

in the vagina After mating, sperm are stored in the spermatheca, a sac connected to the vagina by a short duct.

Testis

1

Accessory gland

3 Seminal vesicle

Vas deferens

Ejaculatory duct

4

Accessory gland

• Concept 46.3: Reproductive organs produce

and transport gametes: focus on humans

• The internal organs are a pair of gonads

carry gametes and house the embryo and fetus

• Reproductive anatomy of the human female

Prepuce

(Rectum) Cervix Vagina

Bartholin’s gland

Vaginal opening

Ovary Oviduct

Labia majora

Labia minora

(Urinary bladder)

(Pubic bone) Uterus

Urethra Shaft Glans Clitoris

Figure 46.9

Follicles Corpus luteum

Ovaries

• Each ovary

contains many follicles

more layers of follicle cells

• The process of ovulation

within the ovary

which secretes hormones, depending on whether or not pregnancy occurs

copulation

baby is born

• The vagina opens to the outside at the vulva

minora, labia majora, and clitoris

reproductive system

the scrotum and penis

and hormones, and accessory glands

• Reproductive anatomy of the human male

Figure

46.10

Erectile tissue

of penis Prostate gland

(Urinary bladder)

Bulbourethral gland

Vas deferens Epididymis Testis

Seminal vesicle (behind bladder)

Urethra Scrotum Glans penis

Seminal vesicle (Rectum) Vas deferens Ejaculatory duct Prostate gland

Bulbourethral gland

(Urinary bladder) (Pubic bone) Erectile tissue of penis

Urethra Glans penis Prepuce

Vas deferens Epididymis

Testis Scrotum

surrounded by several layers of connective tissue

• Production of normal sperm

most mammals

scrotum, where the temperature is lower than

in the abdominal cavity

epididymis

deferens, the ejaculatory duct, and exit the penis through the urethra

ejaculated

semen

• The prostate gland

through several small ducts

neutralizes acidic urine remaining in the urethra

of the uterus, help move the sperm up the uterus

erectile tissue

arteries, causing an erection

predominate in both sexes

• The sexual response cycle can be divided into

four phases

• Concept 46.4: In humans and other mammals,

a complex interplay of hormones regulates

gametogenesis

males

Primary oocyte,

arrested in prophase

of meiosis I (present at birth) Completion of meiosis I and onset of meiosis II

Primary oocyte within follicle

Secondary oocyte,

arrested at phase of meiosis II

meta-First polar body

Ovulation Entry of sperm triggers completion of meiosis II

Ovum

Growing follicle

Mature follicle Ruptured follicle

Ovulated secondary oocyte

Corpus luteum

Degenerating corpus luteum

2n

2n

n n

n n

Figure 46.11

• Spermatogenesis is the production of mature

Sertoli cell nucleus

Lumen of Seminiferous tubule

Spermatids (at two stages of differentiation) Differentiation

(Sertoli cells provide nutrients) Meiosis II Meiosis I completed

Mitotic division, producing large numbers

of spermatogonia

Sperm cells

Acrosome Nucleus Mitochondria

Neck

Tail Plasma membrane

n n n n

Figure 46.12

Differentiation and onset of meiosis I

• Oogenesis differs from spermatogenesis

• First, during the meiotic divisions of oogenesis

cytoplasm monopolized by a single daughter cell, the secondary oocyte

• Second, sperm are produced continuously

throughout a male’s life

uninterrupted sequence

reproductive events they regulate are cyclic

Menstrual Versus Estrous Cycles

• Humans and other primates have menstrual

cycles

cycle

preparation for implantation

• In menstrual cycles

bleeding called menstruation

timeframe

the uterus and ovaries

• Cyclic secretion of GnRH from the

hypothalamus

orchestrates the female reproductive cycle

both positive and negative feedback

• The reproductive cycle of the human female

Figure 46.13a–e

Control by hypothalamus Inhibited by combination of

estrogen and progesterone Stimulated by high levels

of estrogen Inhibited by low levels of estrogen

Hypothalamus

Anterior pituitary GnRH

FSH LH

Pituitary gonadotropins

in blood

LH FSH FSH and LH stimulate follicle to grow LH surge triggersovulation

Ovarian cycle

Growing follicle Mature

follicle

Corpus luteum Degenerating corpus luteum

Estrogen secreted

by growing follicle in increasing amounts

Progesterone and estrogen secreted

by corpus luteum Follicular phase Ovulation Luteal phase

Progesterone and gen promote thickening

10

9

results in ovulation

the corpus luteum

the ovary are integrated with changes in the uterus

endometrium by the end of the secretory phase

secondary sex characteristics of the male

• Androgen secretion and sperm production

reg-FSH acts on the

Sertoli cells of the seminiferous tubules, promoting spermatogenesis.

LH stimulates the

Leydig cells to make testosterone, which

in turn stimulates sperm production.

Anterior pituitary

Negative feedback

Leydig cells make

testosterone

Primary and secondary sex characteristics Sertoli cells

Spermatogenesis Testis

Figure 46.14

• Concept 46.5: In humans and other placental

mammals, an embryo grows into a newborn in the mother’s uterus

carrying one or more embryos in the uterus

• Fertilization of an egg by a sperm, conception

Figure 46.15a, b

Ovary

Uterus

Endometrium

From ovulation to implantation

Cavity

(a)

Implantation of blastocyst (b)

Ovulation releases a secondary oocyte, which enters the oviduct.

1

Fertilization occurs A sperm enters the oocyte; meiosis of the oocyte finishes; and the nuclei of the ovum and sperm fuse, producing a zygote.

4

The blastocyst implants

in the endometrium about 7 days after conception.

5

• After fertilization

into a blastocyst before implantation in the endometrium

three months each

mother and the embryo

• During its first 2 to 4 weeks of development

endometrium

forms the placenta

• Blood from the embryo

– Travels to the placenta through arteries of the

umbilical cord and returns via the umbilical vein

Placenta

Umbilical cord Chorionic villus containing fetal capillaries Maternal blood pools

Fetal venule Umbilical cord

Maternal portion

of placenta

Fetal portion of placenta (chorion)

Umbilical arteries Umbilical vein

Maternal arteries

Maternal veins

Figure 46.16

• The first trimester is the main period of

organogenesis

Figure 46.17a–c

(a) 5 weeks Limb buds, eyes, the

heart, the liver, and rudiments

of all other organs have started

to develop in the embryo, which

is only about 1 cm long.

(b) 14 weeks Growth and

development of the offspring, now called a fetus, continue during the second trimester.

This fetus is about 6 cm long.

(c) 20 weeks By the end of the

second trimester (at 24 weeks), the fetus grows to about 30 cm

in length.

become obvious

available space within the embryonic membranes

• A complex interplay of local regulators and

hormones

which childbirth occurs

from ovaries

from fetus and mother's posterior pituitary Induces oxytocin

receptors on uterus

Stimulates uterus

to contract

Stimulates placenta to make

Prostaglandins

Stimulate more contractions

• Birth, or parturition

uterine contractions

• The process of labor has three stages

Figure 46.19

Placenta Umbilical cord Uterus Cervix

Dilation of the cervix

Expulsion: delivery of the infant

Uterus Placenta (detaching) Umbilical cord Delivery of the placenta

1

2

3

offspring

response in her uterus

• Some contraceptive methods

• Mechanisms of some contraceptive methods

Figure 46.20

Male Female

Method Event Event Method

Production of viable sperm Production ofviable oocytes Vasectomy

Combination birth control pill (or injection, patch, or vaginal ring) Sperm transport

down male duct system

Ovulation Abstinence

Condom Coitus interruptus (very high failure rate) depositedSperm

in vagina

Capture of the oocyte by the oviduct

or injection)

Sperm movement through female reproductive tract

Transport

of oocyte in oviduct

Meeting of sperm and oocyte

in oviduct

Morning-after pill (MAP) Union of sperm and egg

Implantation of blastocyst

in properly prepared endometrium

Birth

Progestin alone

reproductive problems

• Amniocentesis and chorionic villus sampling

or fetal cells are obtained for genetic analysis

• Modern technology