Animal Reproduction (PPT)

Asexual Reproduction

a process that creates identical cells meaning specifically they are genetically identical (mitosis)

Types: Fission, Budding, Fragmentation and regeneration

Sexual Reproduction

the reduction of the chromosome number by ½ creating cells who are genetically unique after fertilization occurs (meiosis)

Fission

an individual divides into 2 equally-sized new individuals - in protists like amoebas

Budding

new individuals “grow” off of parents (corals) or in hydra

Fragmentation and Regeneration

“sponges and sea stars”

new individuals grow when the parent is torn into pieces (lizards)

Parthenogenesis

Eggs develop without being fertilized by sperm. In Daphnia, aphids and rotifers, eggs can be produced through fertilization or parthenogenesis

Bees

Male honeybees are produced parthenogenetically

Female workers and queens develop from fertilized eggs

Hermaphroditism

each has both male and female reproductive organs. Mating still occurs between different individuals

Sequential Hermaphroditism

Individuals physiologically change sex.

Wrasses - a type of fish common to Hawaii, one male lives
with a harem of females, if he is removed or dies the
largest female becomes male. This may take as little time
as 5 days to occur. (female-to-male).

Clown Fish are the exact opposite- slightly larger female dominates a group of small

males. When removed a male changes sex and becomes dominant.

Scrotum

contains testes outside the body wall

Penis

Composed of 3 cylinders of spongy erectile tissue, erectile tissue fills with blood causing an erection

shaft of penis - covered by thick skin

Glans Penis - sensitive thinner head that is covered by a fold of skin called the prepuce which is removed upon circumcision

Urethral canal runs through the penis functions in both excretory system to eliminate urine from the bladder and in the reproductive system as a passageway for sperm to exit the body

Testes

Composed of seminiferous tubules, sperm and the male hormone testosterone are formed in the testes. Sperm form within the seminiferous tubules and mover through them as they mature

Epididymis

located on the dorsal wall of the testis it is a high coiled tube that sperm enter from the seminiferous tubules. Sperm maturation occurs in the epididymis.

Vas Deferens

Sperm enters this duct upon ejaculation. The Vas Deferens carries sperm into the urethra at the ejaculatory duct.

3 Male Reproductive Accessory Glands

Paired Seminal Vesicles

Prostate Gland

Bulbourethral Glands

Paired Seminal Vesicles

adds 60% of the total volume of semen to the ejaculate-it is alkaline, contains fructose, enzymes, ascorbic acid and prostaglandins.

Prostate Gland

Secretes prostatic fluid into the semen large, muscular gland that surrounds the base of the urethra

Bulbourethral Glands

Paired glands that lie along the urethra - they produce a clear fluid before ejaculation, this fluid can contain some sperm cells

Androgens 

Testosterone is primary androgen that is responsive for primary and secondary sex characteristics in males.

Primary Sexual Charachteristics

associated directly with sexual reproduction including formation of ducts, organs and sperm during embryological development.

Secondary Sexual Characteristics

are not directly associated with sex and are usually associated with the changes that occur during puberty, including deepening of voice and the development of facial and pubic hair.

Clitoris

Erectile tissue located at anterior end of the vaginal opening

The clitoris is located at the anterior end of the vestibule, urethral opening is posterior to the clitoris and the vaginal opening is posterior to the urethral opening.

Labia Majora

2 folds of skin that surround the vaginal opening

Labia Minora

Inner folds that line the vaginal opening

Vaginal Vestibule

opening to the vagina

Ovaries

Contain the follicles

Follicle

contains 1 egg cell surrounded by several follicle cells that nourish and protect the developing egg.

one follicle matures each moth and releases and egg upon maturity.

Ovulation

the release of the mature egg from the follicle after its release tissue in the follicle continues to grow forming a corpus luteum

Corpus Luteum

secretes additional estrogen and progesterone during pregnancy 

Fallopian Tube (Oviduct)

Cilia line a funnel-shaped opening that help propel the eggs into the oviduct. The oviduct provides a passageway for the egg to move into the uterus.

fertilization takes place inn the oviduct

Uterus 

thick muscular organ that expands to accommodate a fetus

Endometrium

inner lining of the uterus

Cervix

tip or neck of the uterus that opens into the vaginav

vagina

thin walled chamber that provides the birth canal and the repository for sperm

Menstrual cycle

Consists of 3 phases that cause the changes that occur in the uterus to support pregnancy.

Begins as Day 1- is calculated on the first day of menstrual flow

controls changes in the uterus

If implantation does not occur during the secretory phase- the menstrual flow phase begins again.

Ovarian Cycle

controls the maturation and release of Ova.

Hormones control the maturation and release of eggs from the ovary. There are 2 main phases, the follicular phase and the luteal phase.

Hormones coordinate the menstrual cycle and the ovarian cycle so that the endometrial lining of the uterus is prepared for the possible implantation of an embryo.

Mentrual flow Phase

Endometrium lining of the uterus is shed through menstual bleeding

Proliferative Phase

Endometrium regenerated and thickens

Secretory Phase

The endometrium continues to thicken, producing glands that secrete glycogen, the uterus also becomes highly vascularized during this time to prepare for implantation of the zygote.

if implantation does not occur during the secretory phase - the menstrual flow begins again.

Follicular Phase

Several follicles in the ovary begin to grow.

The pituitary gland secretes follicle stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates the follicles causing them to grow. The maturing follicle cells begin to secrete estrogen. LH causes ovulation to occur.

The egg cell enlarges, and follicle cells become multilayered, only one egg continues to enlarge while the rest degenerate.

Follicle sensitivity to LH increases leading to final maturation

of the egg and ovulation. Ovulation signals the end of the

follicular phase.

Luteal Phase

The LH then acts on the follicle cells left behind

turning them into the corpus luteum. The corpus luteum secretes

estrogen and progesterone to support a pregnancy.

The increased production of estrogen and progesterone inhibit

FSH and LH so that a new pregnancy cannot occur during the

current pregnancy.

Near the end of the luteal phase the corpus luteum disintegrates

and stops producing the estrogen and progesterone. The pituitary then begins to secrete FSH again stimulating follicle growth and the follicular phase begins again.

Menopause

Begins between age of 46-54

Cessation of ovulation and menstruation

Ovaries lose their responsiveness to FSH and LH

Ovaries don’t6t produce enough estrogen too keep the cycle going.

The _____________ is a highly coiled tube that sperm cells become mature in before they are transported to the vas deferens.

Epididymis

The ________________________ is the structure that produces estrogen and progesterone after an egg is released from the follicle cell.

Corpus Luteum

The _____________ is the thick muscular pouch that expands during pregnancy providing a protected ,nutrient rich environment for the fetus to develop in

Uterus

_______________________ produces offspring that are genetically unique and involves the process of meiosis that produces gametes that eventually fuse to form diploid zygotes.

Sexual Reproduction

In _____________ a type of asexual reproduction, the parent splits into 2 equal offspring.

Fission

The testes are located in the ___________________________ a pouch of skin located outside the male body.

Scrotum

A Duct from this accessory gland joins with the vas deferens to form the ejaculatory duct.

Seminal vesicles

These male reproductive structures produce testosterone.

Testes

These structures contain the follicle and follicle cells

Ovaries

In this mode of reproduction each individual organism has functional male and female reproductive organs.

Hermaphroditism

Describe the difference between the menstrual cycle and the ovarian cycle.

The menstrual cycle controls changes in the uterus, focusing on shedding of the endometrial lining. The ovarian cycle regulate the maturation and release of ova (eggs) from the ovary and is divided into 2 phases: The follicular phase and the luteal phase. Hormones coordinate these 2 cycles, preparing the lining of the uterus for implantation of an embryo.