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Flashcards in Male Reproductive System Deck (24):
1

Descent of the Testis

- Testes arise intraabdominally
- starts around 13 weeks
- Develops from meonephric kidney which also develops the excurrent duct system

Gubernaculum
- CT
- As the fetus develops, holds the testis in a lower abdominal position
- in response to hormones, around 7 months, promotes contraction of gubernaculum, it draws the testis down into the scrotum

2

Embryology

- Mesonephric kidney gives rise to part of the testes
- Mesonephric tubules become the efferent ducts
- Mesonephric duct becomes the epididymis
- Mesonephros plays a role in the development of the gonads and retention of the tubules and ducts as part of the excurrent duct system

3

Pampiniform Plexus

Countercurrent heat exchange system
- cools abdominal blood passing to testis and epididymis
- heats blood returning from testis and epididymis to abdomen

4

Testicular Capsule of CT

3 layers
1. Tunica vaginalis
- single layer of cuboidal epithelium

2. Tunica albuginea
- Thickest layer
- CT layer
- Forms the septa that divides into lobules (seminferous tubules within lobules)
- mediastinum - thickening of tunica albuginea with cavities into which sperm from semineferous tubules collect and drain into efferent ducts

3. Tunica Vasculosa
- layer of blood vessels to provide nutrients and oxygen
- goes between tubules

5

.Leydig Cells

- synthesize testosterone
- found between seminferous tubules

- Abundant smooth ER
- Mitochondria with tubular cristae

6

Seminferous Tubules

Epithelium consisting of:
- Sertoli cells (diploid) - support cells
- Germ cells - various kinds (spermatogonia, primary spermatocytes, etc.)


- at the end of each tubule, there is a terminal segment that is sertoli cells only
- this is connected to the tubulus rectus (simple cuboidal epithelium)
- which is then connected to rete testis

7

LH and FSH Control

- LH stimulates leydig cells to produce testosterone
- FSH causes sertoli cells to produce proteins that support germ cels

8

Testosterone

- maintains spermatogenesis
- Maintains accessory glands
- Secondary sex characteristics (facial hair, muscularity)
- Libido - sex drive

9

Testosterone Synthesis

- starts with cholesterol
- have intermediates
- becomes testosterone

- needs to bind to androgen receptor

10

Sertoli Cells

- Create tight junctions with adjacent sertoli cells
- 3 consequences

1. barrier that prevents blood from getting to the germ cells undergoing meiosis

2. compartmentalize the germinal epithelium
- Basal compartment - Has interaction with blood vessels
- Adluminal compartment - no interaction with blood vessels, instead sertoli cells provide nutrients to germ cells (sustaintacular role)

3. Sustentacular role - needed for germ cell viability

11

Spermatogenesis

- going from most primitive spermatogonia to a sperm

spermatogonia undergo various rounds of mitosis

spermatogonia -> primary spermatocytes
- going from 2n to 4n

Primary spermatocytes undergo first meiotic division to produce secondary spermatocytes

Secondary spermatocytes (2n)
- undergo second meiotic division to produce round spermatid

Rounded spermatids - hapoid, 1n
- undergoes elongation to create spermatids

12

Spermiogenesis

- going from a rounded spermatid to an elongated sperm

13

Spermatids

- 1n DNA content = haploid
- acrosomal granule on one end - flattens out on top of the nucleus

- The other end contains centrioles
- from the distal centriole you get the formation of the axoneme (9+2 arrangement of microtubules)

- around the axoneme, mitochondria gather to form the middle piece

- residual body - excess cytoplasm
- phagocytized by the sertoli cells

14

Sperm

Head
- contains DNA
- Acrosome contains hydrolytic enzymes
- needed for going through the follicle for fertilization of the ooctye

Mid Piece
- axoneme (9+2) arrangement of microtubules
- surrounded by outer dense fibers (9 of them)
- surrounded by mitochondrial sheath- provides energy for motility

Principle piece
- axoneme surrounded by outer dense fibers
- mitochondria are replaced by fibrous sheath

End piece
- axoneme only

15

Rete Testis

- Sperm is released from the semineferous tubules into the rete testis
- Rete are spaces in the mediastinum of the tunica albuginea
- lined by simple cuboidal epithelium
- occasional cilia

16

Efferent Ducts

- ductus efferentes
- derived from the meosnephric tubules of the mesonephric kidney
- about 20 ducts bundled together

- lined by ciliated cells and resportion cells
- ciliated cells help to move the sperm along
- Resorptive cells- reabsorb 95% of fluid before entering the epididymis
- becomes very concentrated

17

Epididymis

- one long duct that is highly folded and coiled upon itself
- psuedostratifed columnar epithelium with sterocilia

- reabsorbs fluid, concentrating the sperm

- As sperm goes through the epididymis, from the head to vas deferens, there is an increase in ability to fertilize an oocyte
- The diameter of the duct increases, the flow rate of the sperm declines as it reaches the end of the epididymis

18

Ductus (vas) Deferens

- same tube as epidiymis, therefore derived from the mesonephric duct

- more smooth muscle - used for ejaculatory process
- inner and outer longitudinal
- middle circular

Epithelium becomes more folded
- Folds increase in size as you go down the ductus vas deferens
- lots of folds as you get to the ampulla region

19

Seminal Vesicles

- Pair of seminal vesicles attached to each vas deferens
- Contains one tube that's highly folded
- simple columnar or pseudostratified columnar epithelium
- secrete fluids during ejaculation that helps to promote the viability of the sperm

20

Prostate Gland

- sits at the base of the bladder
- the two ejaculatory ducts (vas deferens) go thorugh it

- transitional, central and Periurethral zones
- contains more smooth muscle

Lining epithelium is pseudostratified or simple columnar

corpora amylacea
- shows up in the prostate of aging men

21

Bulbourethral Glands

- Cowper's Glands
- Alveolar Gland
- Secretes mucin
- Base of the penis

Lines the urethra
- protecting from acrosomal proteases
- protects sperm from remains of urine

- skeletal muscle is histologically unique structure

22

Penis

The root
- fixed end of the penis which attaches it to the body wall

The body
- mobile tubular portion

The glans
- expanded distal end surrounding the urethral orifice

23

Histology of Penis

- Paired corpus cavernosum
- Surrounded by CT capsule (tunica albuginea)

- very similar to the clitoris
- urethra surrounded by the corpus spongiosum

24

Male Urethra

Prostatic urethra
- passes through the prostate
- transitional epithelium - some epithelium that lines the prostate

Membranous urethra
- psuedostratified/ stratified columnar epithelium

Penile Urethra
- pseudostratified/ stratified columnar epithelium