CH 28 - Reproductive Systems

Reproductive Structures

Gonads (testes and ovaries: produce gametes), Ducts, Acessory glands, external genitalia.

Male Reproductive Functions

Testis produce sperm.
Epididymis→ductus deferens/vas deferens→Ejaculatory duct→urethra→external environment
Accessory organs: Seminal, prostate, bulbo-urethral glands.
External Genitalia: Scrotum and penis

Descent of Testes

Form inside abdomen. Gubernaculum testis is a bundle of connective tissue fibers. The body grows but the gubernacula stay the same time. Surge of testosterone pushes them through the inguinal canal at around 7 months. If only one has descended at birth it is called cryptorchidism. If is still does not descend after a few months, it can lead to sterility.

Scrotum

Skin covered sac that contains the testes. Each in a separate scrotal chamber that is lines with spermatic fascia.

Raphe

The midline ridge of the scrotum.

Sperm temperature

usually 2-3C cooler than the average temperature of the body for best sperm production.

Dartos Muscle

Smooth muscle in the dermis of the scrotum, elevates scrotum, thermal regulation

External spermatic fascia

aponeurosis of external oblique muscles

Cremaster muscle

Skeletal muscle from extensions of internal oblique muscles, thermal regulation

Internal spermatic fascia

Deep abdominal muscles

Cremasteric Reflex

Tenses scrotum and elevates testes during temperature regulation and sexual arousal.

Tunica vaginalis

Serous membrane, covers testis and spermatic cord

Tunica albuginea

dense layer of connective tissue, forms fibrous partitions that converge near entrance to epididymis.
The septa subdivide the testis into lobules
The lobules contain seminiferous tubules where sperm is produced. Converge to rete testis

Interstitial Cells

Found between tubules, produce androgens, testosterone is the most important

Nurse cells

Within seminiferous tubules, support spermatogenesis

Spermatogenesis

Spermatogonia: (stem cells) divide by mitosis
Primary spermatocytes: begin meiosis
Secondary spermatocytes: haploid cells begin meiosis II
Spermatids: end result of meiosis
Differentiate into Spermatozoa

Spermiogenesis

Last step of Spermatogenesis. Spermatid matures into spermatozoon which enters lumen of tubule. MAture sperm production take about 9 weeks

Epididymis

Start of male reproductive tract. Monitors and adjusts fluids produced by seminiferous tubules. Recycles damaged spermatozoa. Stores and protects spermatozoa.

Ductus Deferens (vas deferens)

From epididymis through inguinal canal.

Ejaculatory Duct

Short passageway at junction of ampulla and seminal gland duct. Penetrates wall of prostate gland and empties into the urethra.

Accessory gland functions: male

Produce semen. The semen activates spermatozoa, provide nutrients for mobility, propel them along with peristaltic contractions, and produce buffers to counteract acidity of urethral and vaginal environments.

Accessory Glands: Seminal Vesicles

Produce 60% of semen volume. Seminal fluid has a high concentration of Fructose. Prostaglandins stimulate smooth muscle contractions. Fibrinogens form temporary semen clot in vagina.

Accessory Glands: Prostate Gland

Encircles proximal portion of urethra. Prostatic fluid forms 20-30% of semen volume. Contains antibiotic seminalplasmin.

Accessory Glands: Bulbo-urethral glands

Located at the base of penis. Secrete alkaline mucus prior to ejaculation, provide lubrication and neutralize acidic urethra.

Accessory Glands: Semen

Mixture of sperm (20-30 million), fluid (2-5 mL), and enzymes.

Penis

Corpora Cavernosa: 2 cylindrical masses of erectile tissue located under the anterior surface
Corpus spongiosum: Surrounds the penile urethra.
Parasympathetic stimulation causes vasodilation→Increased blood flow causes erection.

Gonadotropin-releasing hormone: male

hypophyseal portal system delivers to anterior pituitary Controls rates of secretion of FSH (Follicle Stimulating Hormone) and LH (Leutinizing Hormone)
LH targets interstitial cells →Testosterone
FSH and testosterone target nurse cells →Testosterone and inhibin (secreted by nurse cells) exert negative feedback

Female reproductive system

protects and supports developing embryo, nourishes newborn infant. ovaries, uterine tubes, uterus, vagina, and the external genitalia

Ovary Functions

Production of immature female gametes (oocytes), Secretion of estrogens and progestins, secretion of inhibin for feedback and control of pituitary secretion of FSH

Germinal epithelium

Surrounds ovary and is made of simple cuboidal ET. Does not produce gametes. Gametes are produced in the cortex

Ovarian Cycle 1

Primary oocytes located in egg nests. Single layer of follicle cells surrounds primary oocytes. (Primordial follicles)

Ovarian Cycle 2

Primordial follicles mature into Primary Follicles. Single layer of cuboidal granulosa cells (follicle Cells). Zona pellucida: Glycoproteins that surround the oocyte

Ovarian Cycle 3

Secondary Follicle contains primary oocyte, multiple layers of granulosa cells, Thecal cells form additional layer. Granulosa and thecal cells produce estrogens
Antral follicle: Granulosa cells secrete follicular fluid - creates antrum, corona radiata

Ovarian Cycle 4

Mature Follicle: Usually only 1 mature cell per ovarian cycle. Primary oocyte completes meiosis 1 and matures into a secondary oocyte.

Ovarian Cycle 5

Ovulation occurs when the mature follicle releases the secondary oocyte. It is surrounded by the corona radiata. The Fimbriae and fluid currents move the oocyte into the uterine tube.

Ovarian Cycle 6

The empty follicle collapses, and creates endocrine structure called the Corpus Luteum. Progesterone prepares the uterus for pregnancy

Ovarian Cycle 7

The corpus luteum degenerates to form the Corpus Albicans. This is a fibrous scar tissue and marks the end of the ovarian cycle.

Uterine Tubes/Fallopian tubes/oviducts

Transport oocyte from ovary to uterus. Infundibulum is expanded funnel near ovary, Ampulla is the middle segment, Isthmus is a short segment between ampulla and uterine wall.

Uterus Regions:

body, fundus, isthmus, and cervix (external os, internal os, and cervical canal).

Uterine Wall: Perimetrium

Incomplete serous membrane, continuous with peritoneal lining. Outer lining

Uterine Wall: Myometrium

Longitudinal, circular and oblique. Middle layer

Uterine Wall: Endometrium

Glandular, and vascular tissue. Uterine glands and uterine arteries. Basilar zone attaches endometrium to myometrium. Deepest layer

Uterine Cycle

Changes in endometrium. Destruction of functional zone (Menses), Repair and regen of functional zone (Proliferative), Secretion by uterine glands (Secretory phase).

Vagina cells

Stratified squamous epithelia that is not keratinized, to maintain moisturized mucous layer.

Mammary Glands

Nipples contains lactiferous sinuses, areola is the pigmented area surrounding each nipple. Do not develop completely unless pregnancy occurs.

Follicle Stimulating Hormone (FSH)

initiates follicular development. The levels decline due to negative feedback of inhibin. The developing follicles secrete estrogens. regulates sexual development and reproduction by stimulating egg growth in females and sperm production in males

Luteinizing Hormone (LH)

peak in LH secretion stimulated final development of oocyte, ovulation, and formation of corpus luteum. After ovulation, corpus luteum primarily releases progesterone. triggers testosterone production in men and ovulation (egg release) and estrogen/progesterone in women

Male sexual arousal leads to

An increase in parasympathetic outflow, leads to erection

Sympathetic outflow(male)

Leads to emission and ejaculation. Detumescence is the time frame between ejaculations. The erection will decline and reengorge between emission.

Parasympathetic Activation (female)

Leads to engorgement of erectile tissues, secretion of cervical glands. Female orgasm is accompanied by peristaltic contractions of uterine and vaginal walls.

Menopause

45-55. Ovulation and menstruation stop. Estrogens and progesterone levels decline. GnRH, FSH, and LH increase.

Male Climacteric

50-60. Testosterone decline, FSH and LH increase. Sperm production continues