REPRODUCTIVE SYSTEM AND DEVELOPMENT

Male Reproductive Structures

Female Reproductive Structures

Meiosis

Hormones of the Reproductive System

Male Hormones

Female Hormones

Menstrual Cycle

Embryonic Development

Fetal Development

Primary Reproductive Organs

Accessory reproductive organs

Ovaries

Uterine tubes

Uterus

Vagina

External genitalia

Mammary glands

Paired within the pelvic cavity

Supplied by ovarian artery and ovarian vein

Contains ovarian follicles

Transports oocyte to uterus

Site of fertilization

Pear-shaped

Muscle

Site for implantation of embryo

Which contains oocyte

Copulatory organ

Passageway for menstruation

Birth canal

Mons pubis

Labia majora

Vestibule

Urethral opening and vaginal opening

Clitoris

Erectile tissue

called

Corpora cavernosa

Prepuce

Fold that covers clitoris

Secretory

Breast milk

provides nutrients for baby

Primary Reproductive Organs

Testes

Secondary Reproductive Organs

Penis

Organ for copulation

Passageway for urine and semen

Complex set of ducts and tubes

Homologous to scrotum

Scrotum

Homologous to labia majora

Labia minora

Spermatic cord

Blood vessel and nerve supply

Produce sperm

Produce androgens

Testosterone

Epididymis

Stores sperm until matured

From epididymis

to vas deferens

to ampulla

to seminal vesicle

ejaculatory duct

to urethra

Accessory glands and semen production

seminal vesicles

prostate gland

bulbourethral glands (Cowper glands)

semen

secretes a viscous, whitish-yellow, alkaline fluid

contains prostaglandins and fructose

facilitates sperm entry into the uterus

produce mucin

secretes a milky fluid slightly acidic and rich in citric acid, seminalplasmin, and prostate-specific antigen (PSA)

Sperm and urinary tract health

serves to neutralize the acidity of the vagina

secretes a clear, viscous mucin that forms mucus

Coats and lubricates the urethra for passage of sperm

Seminal fluid from the accessory glands combined with sperm

Oogenesis

Spermatogenesis

Begins at puberty

Occurs within the seminiferous tubule

Spermatogonia

Germ cells that are the origin of sperm are diploid cells (containing 46 chromasomes)

Mitotic divisions of these cells produce a new germ cell and a committed cell

Committed cell is a primary spermatocyte

Meiosis I begins in the diploid primary spermatocytes. The haploid cells (23 chromasomes) produced during meiosis I are called secondary spermatocytes

Meiosis II originates with the secondary spermatocytes and produces spermatids

Meiosis I Begins in fetal development and pauses until puberty

Oogonia

Diploid cells (containing 46 chromosomes)

Oogonia divide by mitosis and differentiate to produce primary oocytes

Remains at prophase I until puberty

When puberty begins

Approximately 20 primordial follicles mature into the primary follicles every month

Some primary follicles mature into secondary follicles

Primary follicles that do not mature undergo atresia

Only one secondary follicle matures into a mature follicle, where the primary oocyte completes the first meiotic division to produce a polar body and a secondary oocyte. The secondary oocye is a haploid cell (23 chromosomes) that is arrested in the second meiotic metaphase

If secondary oocyte is fertilized, it completes the second meiotic division and becomes an ovum. If the secondary oocyte is not fertilized, it degenerates

Hypothalamus initiates the ovarian cycle by secreting GnRH which stimulates the anterior pituitary to secrete FSH and LH

FSH & LH target the ovaries and stimulate follicular development

This causes maturation of follicles

Maturing ovarian follicle secrete inhibin and estrogen

Inhibin helps inhibit FSH release by the anterior pituitary, low levels of estrogen inhibit production of GnRH, FSH, and LH

Estrogen assists with development of the mature ovarian follicle

Mature follicle produces a larger threshold amount of estrogen

Positive feedback loop results in an LH surge from the anterior pituitary which induces ovulation

Corpus luteum forms from the ovulated follicle

Corpus luteum secretes large amounts of progesterone, estrogen, and inhibin

Inhibits both hypothalamus and anterior pituitary and builds uterine lining

Degenerates in 10-13 days if not fertilized

Results in decreases in hormone levels

Shedding of uterine lining

Cycle repeats

Hypothalamus begins secreting GnRH at puberty

Hypothalamus

Stimulates GnRH

That stimulates the anterior pituitary

To secrete

Follicle Stimulating Hormone

Leutenizing Hormone

Stimulates the development of the follicle from primary through mature stages

Stimulates mature follicle to secrete estrogen and progesterone

stimulates meiosis in primary oocyte

GnRH stimulates anterior pituitary

to secrete FSH and LH

LH stimulates the testes to produce testosterone and androgens

Testosterone stimulates final stages of sperm development in seminiferous tubules

Pre-embryonic period

Fertilization

Sperm penetrates secondary oocyte; secondary oocyte completes meiosis II and becomes an ovum; ovum and sperm plasma membranes fuse

Zygote

Diploid cell produced when ovum and sperm pronuclei fuse

Cleavage

Zygote undergoes cell division by mitosis to increase cell number, but overall size of structure remains constant

Morula

Structure formed resembles a solid ball of cells; 16 or more cells are present, but there is no change in diameter from original zygtote

Blastocyst

Hollow ball of cells; outer ring formed by trophoblast; inner cell mass (embryoblast is a cell cluster inside blastocyst)

Implantation

Ampulla of uterine tube within 12-24 hours after ovulation

Ampulla of uterine tube at the end of fertilization

In the uterine tube 30 hours to day 3 post-fertilization

Uterine tube days 3-4 post-fertilization

In the uterus days 5-6

Functional layer of endometrium of uterus and begins late first week and is complete by end of second week

Blastocyst adheres to functional layer of uterus; trophoblast cells and functional layer together begin to form the placenta

Embryonic period

First 2 weeks of development

3 - 8 weeks of development

Now called an embryo

Fetal period

Remaining 30 weeks of development prior to birth

Weeks 9-12

Primary ossification centers appear in most bones

Reproductive organs begin to develop

Coordination between nerves and muscles for movement of limbs occurs

Brain elongates and enlarges

Epidermis and dermis of the skin become more fully developed

Permanent kidneys develop

Palate develops

9 centimeters and 28 grams

Weeks 13-16

Body grows rapidly

Ossification in the skeleton continues

Limbs become more proportionate in length to body

Brain and skull continue to enlarge

14 centemeters and 170 grams

Weeks 17-20

Muscle movements become stronger and more frequent

Lanugo covers skin

Limbs near final proportions

Brain and skull continue to enlarge

19 centemeters, 454 grams

Weeks 21-38

Body gains major amount of weight

Subcutaneous fat is deposited

Eyebrows and eyelashes appear, eyes open

Testes descend to scrotum if a boy

Blood cells form in marrow only

38 weeks - 36 centemeters, average weight 2.5-4.5 kilograms

The process of spermiogenesis begins with the spermatids and results in morphologic changes needed to form sperm that will be motile

Houses testes

Corpus Cavernosum

Corpus spongiosum

Homologous to female clitoris

In seminiferous tubules

Homologous to penis