Chapter 26

The Reproductive System

Gametes

Sex cells

• Sperm (spermatozoon) - has motility for achieving contact

• Egg (Ovum)- has nutrition for developing embryo

Zygote

A fertilized egg formed by the union of a sperm and an egg, it undergoes division to develop into an embryo.

Males have ..

• Y & X chromosomes

• Penis for introducing sperm

Females have..

two X chromosomes

vagina for receiving sperm

What are the primary sex organs (gonad)?

• male-testes

• females-ovaries

What are the secondary sex organs?

• males- ducts, glands, penis

• female- uterine tubes, uterus, vagina

• internal and external genitalia

• secondary sex characteristics

Meiosis (first division) steps think P-mat

Early prophase I (starts diploid) → Mid- to late prophase I→ Metaphase I→ Anaphase I→ Telophase I

Diploid

DNA combination resulting in our double-stranded chromosomes (DNA from Mom and Dad)- all cells except sperm/egg

Early prophase I (starts diploid)

Chromatin condenses to form visible chromosomes; each chromosome has 2 chromatids joined by a centromere.

Mid- to late prophase I

Homologous chromosomes form pairs called tetrads. Chromatids often break and exchange segments (crossing-over). Centrioles produce spindle fibers. Nuclear envelope disintegrates.

Metaphase I

Tetrads align on equatorial plane of cell with centromeres attached to spindle fibers.

Anaphase I

Homologous chromosomes separate and migrate to opposite poles of the cell.

Telophase I

New nuclear envelopes form around chromosomes; cell undergoes cytoplasmic division (cytokinesis). Each cell is now haploid.

Meiosis II (Second Division)

Prophase II→ Metaphase II→ Anaphase II→ Telophase II, the chromatids separate and are distributed into two new nuclei.

Prophase II

Nuclear envelopes disintegrate again; chromosomes still consist of 2 chromatids. New spindle forms.

Metaphase II

Chromosomes align on equatorial plane.

Anaphase II

Centromeres divide; sister chromatids migrate to opposite poles of cell. Each chromatid now constitutes a single-stranded chromosome.

Telophase II

New nuclear envelopes form around chromosomes; chromosomes uncoil and become less visible; cytoplasm divides.

• Final product is 4 haploid cells with single-stranded chromosomes.

Haploid

DNA combination resulting in a single stranded chromosomes. Only cells are sperm/egg

The scrotum

is a pouch of skin containing the testicles, includes the spermatic cord, and helps to regulate their temperature for optimal sperm production.

Median septum in Scrotum

Perineal raphe – external seam

Spermatic cord

• Ductus deferens, nerves, and vessels

• Inguinal canal to pelvic cavity

Temperature regulation (Scrotum) contains?

• Cremaster

• Dartos muscle

• Pampiniform plexus

Pampiniform plexus

vein network of spermatic cord

Dartos muscle

smooth muscle that wrinkles scrotum

cremaster

internal oblique muscle that elevates the testes

The testes (testicles) two types of connective tissue

• Tuina vaginalis

• Tunica Albuginea

The testes have hundreds of lobules of 1 to 3 seminiferous tubules which include:

• Germinal epithelium

• Sustentacular (Sertoli) cells

• Interstitial (Leydig) endocrine cells

Interstitial (Leydig) endocrine cells

between tubules make testosterone

Sustentacular (Sertoli) cells

help make blood-testies barrier

Germinal epithelium

Germ cells become sperm

Rete testis

beginning of sperm maturation process

Spermatogenesis steps

1. Type A spermatogonium undergoes mitosis forming one Type A and one Type B spermatogonium.

2. Type B spermatogonium becomes primary spermatocyte.

3. Primary spermatocyte undergoes meiosis I forming two haploid secondary spermatocytes.

4. The secondary spermatocytes undergo meiosis II forming four haploid spermatids.

5. The spermatids differentiate into sperm (process called spermiogenesis).

Spermiogenesis

1. Appearance of acrosomal vesicle and flagellum in spermatid

2. Growth of acrosome and flagellum

3. Shedding of excess cytoplasm

4. Mature sperm

Head of spermatozoa contains:

• Nucleus

• Acrosome- Enzymes

• Flagellar basal body

Tail of spermatozoon contains:

• Midpiece- many mitochondria for energy

• Principle piece of tail

• end of tail

The spermatic ducts include

• efferent ductules

• epididymis

• Ductus (vas) deferens

• ejaculatory duct

• urethra

Efferent ductules

• Posterior testis

• Carry sperm to epididymis

Epididymis

• Head, body, and tail

• Sperm storage and maturation

Ductus (vas) deferens

• Long tube with smooth m. in wall

• Ampulla is widened last portion

Ejaculatory duct

• Passes through prostate

• Empties into urethra.

Urethra

Prostatic, membranous, spongy

The accessory gland includes

• Seminal vesicles

• Prostate

• Bulbourethral glands

Components of Semen

• 2 to 5 ml per ejaculation

• 10% sperm

  • Sperm count about 50 to 120 million/mL.

• 30% prostatic fluid

• 60% seminal vesicle fluid

Seminal vesicles

• Pair of glands, posterior to bladder

• Empty into ejaculatory duct

Prostate

• Surrounds urethra and ejaculatory ducts

• Empties into urethra

Bulbourethral glands

• Pair of glands near base of penis

• Secretes clear fluid that neutralizes

  urethra, lubricates head

The penis includes

• Internal root

• Shaft

• Glans- head

  • frenulum

• Prepuce (foreskin)

• erectile tissue

  • corpus spongiosum (1)

  • Corporal cabernisa (2)

    • contains Deep arteries

The Female Reproductive System Overview

The Internal Female Reproductive Tract

Ovaries structure includes:

• Tunica Albuginea

• Medulla

• Cortex

• Follicles

What do the follicles in the ovary include?

• egg and supporting follicular (granulosa) cells

What does the cortex of the ovary include?

Follicles

The medulla of the ovary?

Fibrous connective tissue w/ blood vessels

Tunica Albuginea of Ovary

capsule around ovary

Oogenesis (Left) and Corresponding Development of the Follicle (Right)

• Occur somewhat simultaneously

Oogenesis

• Primary oocyte (diploid) completes meiosis I forming one secondary oocyte and one polar body (both haploid)

• Secondary oocyte is ovulated and will complete meiosis II if fertilized (produces and discards a second polar body)

Folliculogenesis

• Primordial follicle

• Primary follicle

• Secondary follicle cells

• Tertiary follicle

• preovulatory (graafian) follicle

Primordial follicle

egg and one layer of follicular cell

Primary follicle

larger egg, one layer of cuboidal follicular cells

Secondary follicle

larger egg, two or more layers of granulosa cells

Tertiary follicle

contains fluid-filled pockets or a single fluid- filled antrum among granulosa cells

Preovulatory (graafian) follicle

• large blister bulging from ovary

  • Contains cumulus c with zona pellucida as inner layer

Oogenesis and Folliculogenesis

• Ovulation of secondary oocyte from mature (Graafian) follicle occurs around day 14 of menstrual cycle

• Collapsed follicle becomes corpus luteum

  • If there is no pregnancy, it involutes and becomes corpus albicans – a scar

The Uterine Tubes/Oviducts/Fallopian Tubes

• Ciliated tube from ovary to uterus

• Fimbriae project from Infundibulum toward ovary

  • Fimbriae perform a sweeping motion over ovary to draw oocyte into the tube – they are NOT connected!

• Ampulla- middle segment

• Isthmus- narrow, near uterus

Uterus

A muscular chamber superior to vagina for nourishment, protection, and delivery of fetus

• Sections: fundus, body, and cervix

  • Cervical canal (with cervical glands) connects to vagina

Uterine wall layers and types? (deep to superficial)

• Perimetrium – external serosa.

• Myometrium – smooth muscle

• Endometrium

  • Functional layer – superficial, shed during menstruation

  • Basal layer – regenerates new lining every month

The vagina includes

Distensible wall of mucosa, muscularis, and adventitia

• Fornices

• Vaginal Rugae

• Hymen

Fornices

superior extensions around cervix

Vaginal rugae

friction ridges and allows for distension during sexual intercourse and childbirth

Hymen

membrane across opening. Not a sign of virginity.

The Female External Genitalia includes:

Vulva (pudendum) – external genitalia

• Mons pubis

• Labia majora (majus)

• Labia minora (minus)

• Vestibule

• Clitoris

Clitoris

• Erectile; area of sexual stimulation

  • Prepuce – hood over clitoris

  • Glans, body, crura

Vestibule of external female genitalia

Area enclosed by labia minora

Labia majora vs labia minora

Majora (majus)

• thick folds between thighs

Minora (minus)

• hairless, thin, medial folds

Mons pubis

• Anterior mound

• The rounded fatty tissue located over the pubic symphysis, providing cushioning and protection.

vestibular bulbs of female external genitalia is ?

Erectile tissues deep to labia majora.

What are the glands providing lubrication to vestibule and vagina?

• Greater and lesser vestibular glands

• Paraurethral glands

The breast externally has

the areola that surrounds the nipple

Each breast internally contains:

• Suspensory ligaments

• Adipose Tissue

• Mammary Glands

  • Modified sweat glands to produce human “milk”

The suspensory ligaments of the breast attach what?

• attaches the dermis to the fascia of pectoralis major muscle

Each lobe of the mammary gland is drained by a

lactiferous duct

Each lactiferous duct drains into a ________ before exiting through the nipple

lactiferous sinus

Review of M/F External and Internal Genitalia

Beginning of adolescence terms

• Thelarche

• Pubarche

• Menarche (females)

*Puberty ends at sexual maturity

Menarche

females only

development of menstruation

Pubarche

development of hair and sebaceous glands

Telrache

testes, scrotum, breast development

Male climacteric (andropause)

declining reproductive function beginning in 50s

• Testosterone level, sperm count, and libido decline

• Incidence of erectile dysfunction (impotence) increases

Menopause (female)

• (cessation of menstruation) occur between ages 45 and 55

  • Reproductive organs atrophy

  • Hormonal changes cause hot flashes, decreased bone mass, thinner skin, higher cholesterol

Climacteric (female)

decline of ovarian function

Prostate cancer

Affects 9% of men over 50

Testicular cancer

Most common tumor in men 15 to 34 years old

Breast cancer

• Occurs in 1 of every 8 or 9 women in America

• Can also occur in males!

Cervical/Anal cancer

Slow growing neoplasia caused by Papilloma virus that can be detected by Pap smear

Sexually transmitted diseases

• AIDS, Hepatitis C, Herpes Simplex 1 and 2, Genital warts (see above) caused by viruses

• Gonorrhea, Chlamydia, Syphilis, etc. caused by bacterial infections