AVS 472 Exam 2 Review - Male Reproductive Anatomy + Fertilization Processes

scrotum

External sac that contains the testes, functions of protection, thermosensor, and radiator

thermosenor function of scrotum

retraction/extension with weather

radiator functions of scrotum

5° cooler than the rest of the body

tunica dartos

smooth muscle which lines scrotal wall, androgen dependent to maintain tone, when environment I cold it will contract, forces testis closer to body cavity and vice versa

Gubernaculum

band of connective tissue that attaches testes to scrotum

parietal vaginal tunic

Thick outer layer

Forms a fibrous sac around each testis and spermatic cord

visceral vaginal tunic

lies directly on the testes, epididymis, and ductus deferens

parenchyma

functional tissues of any organ, such as the tissues of the bronchioles, alveoli, ducts, and sacs, that perform respiration

mediastinum

series of networks where all sperm being produced converge in the common area of mediastinum to go the rest of way through the system

tunica albuginea

fibrous capsule of the testes

rete testis

network of tubules between the seminiferous tubules and the epididymis

epididymis

A long, coiled duct on the outside of the testis in which sperm mature.

vas deferens

tube that carries sperm from the epididymis to the urethra

caput epididymis

head of epididymis

corpus epididymis

body of epididymis

cauda epididymis

tail of the epididymis

vas efferentia

The tiny tubules that carry sperm to the head of the epididymis.

Where are sperm stored?

cauda epididmyis

how is movement through the epididymis conducted?

peristalsis

spermatic cord

extends upward from the epididymis and is attached to each testicle, contains vascular, lymphatic, nervous tissue, pampiniform plexus, and cremaster muscle

pampiniform plexus

an extensive network of veins from the testes that surrounds the testicular artery and spermatic cord. Reduced heat, concentrates tester one, and reduced amplitude and arterial pulses

Testosterone concentration of the testis

70ng T/mL

testosterone concentration in the body

4.8 ng T/mL

cremaster muscle

skeletal muscle that arises from the internal obliques; elevates testes

ampulla

The ampulla of vas deferens is an enlargement of the vas deferens near the bladder. It contributes secretions to the semen, including fructose and ergothioneine.

seminal vesicles

two small glands that secrete a fluid rich in sugar that nourishes and helps sperm move

body of prostate

The prostate gland, a walnut-sized organ in the male reproductive system, produces fluid that becomes part of semen, which nourishes and carries sperm during ejaculation.

disseminate prostate

Glandular tissue distributed along the dorsal and lateral walls of the pelvic urethra

Cowper's gland

either of a pair of small glands that open into the urethra at the base of the penis and secrete a constituent of seminal fluid. illicitness a preejaculate upon erection, doesn't contain sperm, cleans urethra of urine and bacteria

bulbourethral glands

Cowper's glands

sigmoid flexure

"S" shape in urethra allows for extension of penis outside of body for reproduction

retractor penis muscle

attached to the sacral vertebra. Relaxes during sexual excitement

corpus cavernosum

Pair of spongy tissue regions full of blood during erection

corpus spongiosum

surrounds the urethra

large veins in corpus cavernous

collapse during erection to allow for blood to pool, port to leave

raphe

vestige of where the prepuce extended when its unsheathed during sexual maturity

which animals have vertical orientation of testis

bull, ram, rabbit, human

which animals have oblique orientation of testis

boar, dog

what animal has horizontal orientation of testis

stallion

ram anatomy feature

no body of prostate (smaller amount of seminal fluid)

boar anatomy features

no ampulla, but large Cowper's gland (large amount of seminal fluid)

stallion anatomy features

no disseminate prostate, enlarged seminal vesicles

dog anatomy features

no seminal vesicles, disseminate prostate, or Cowper's glands

tom anatomy features

no seminal vesicles or disseminate prostate

human anatomy features

no disseminante prostate

muscular-vascular penis

engorged in length and diameter, stallion, humans, cats, and dogs

fibroelastic penis

engorged in length only, bull, ram, and boar

seminiferous tubules

Narrow, coiled tubules that produce sperm in the testes.

spermatogonium

A diploid cell that can undergo mitosis to form more spermatogonium, and can also be triggered to undergo meiosis to form sperm.

myoid cells

smooth muscle-like cells surrounding seminiferous tubule that contract to squeeze sperm and testicular fluid through tubules

secondary spermatocytes

Haploid cells resulting from the first meiotic division of spermatogenesis. Secondary spermatocytes are ready to enter meiosis II.

primary spermatocyte

specialized cell that undergoes meiosis to ultimately form sperm

round spermatids

Found closer to the centre of the seminiferous tubules. First stage of differentiation in spermatogenic cycle

spermatid

an immature male sex cell formed from a spermatocyte that can develop into a spermatozoon without further division.

Sertoli cells

cells found within the seminiferous tubules that provide metabolic support for the spermatids, responds to FSH

Leydig cells

A cell that produces testosterone and other androgens and is located between the seminiferous tubules of the testes, responds to LH , have blood supply access

spermatozoa

a mature sperm cell

primary sex cords in fetal testis

monocytes are precursors to spermatogonia, bulk of cord is made up of pre-sertoli cells secreting AMH (determines sex), fetal leydig cells secrete tester one as well, additionally suppressing female tract. The lending cell will support development of the male track

FSH on Sertoli cells

1. stimulates spermatogenesis by synthesizing and secreting growth factors

2. stim synthesis and secretion of ABP which concentrates testosterone in the lumen of the seminiferous tubules and brings tester one to epididymis

3. Sertoli cells produce inhibit which inhibits FSH secretion from the ant pituitary (negative feedback)

4. Produces estradiol

5. aids tight junctions which separate diploid from haploid cells

bulbus glandis

enlargement toward the rear of the glans of dogs, inflates to allow penis to "lock" into vaginal canal of bitch

what species have sigmoid flexures

bull, ram, boar

Spermatocytogenesis

differentiation of spermatogonia into primary spermatocytes

spermiogensis

maturation of spermatids into sperm cells

how long does the production of sperm take

about 2 months

How many pulses of LH/FSH/GnRH are in a 24 hour period of a male?

4-5

Why are pulses important?

to keep Leydig cells sensitive to LH, excess t4 can suppress Sertoli cell function, a high amount of t4 is needed for spermatogenesis

3 phases of spermatogenesis

proliferation, meiotic, differentiation

proliferation

mitotic division near basement membrane, goal of generating a large number of spermatogonia (three types A,I, and B)

meiotic phase of spermatogenesis

spermatocytes undergo meiosis to generate haploid spermatids, between 2-6 divisions, cytoplasmic bridges form between daughter cells, apoptosis can occur at rates as high as 75% meiosis one for primary and meiosis two for secondary

things that can affect apoptosis of spermatogonia

normal part, season, disease, trauma or heat, hormone levels

Differentiation phase of spermiogenesis

transformation of round spermatid to elongated spermatozoa, four phases ( golgi, cap, acrosomal, and maturation phases)

Golgi phase of differentiation

*Initial acrosome formation

*Initial tail development

*translocation of centrioles

cap phase of differentiation

acrosome membrane formed, produce hydrolytic enzymes, flagellum elongates

Acrosomal phase of differentiation

*Large acrosome

*nucleus elongates

*manchette forms

*Neck and annuls form

maturation phase of differentiation

Final sperm assembly

*Spermatid becomes spermatozoon

*Mitochondria surround mid-piece as helix

*Completion of tail

*golgi removed

*Spermiation

cytoplasmic droplet

a remnant of cytoplasm located either at the neck of the spermatozoon (proximal) or just posterior to the midpiece of the spermatozoon (distal), as the migration of the sperm to the nail of epididymus it will migrate towards the end and be removed, can be used as a way to determine if you are overworking a male

stages of spermatogenesis

1-8 stages per cycle, each stage represents a window of time of and a snapshot as to what that tubules may look like at a given time , differ in duration

duration of the cycle of the seminiferous epithelium

time required to complete a from a spermatogonia to spermatozoon

how many cycles must a somniferous tubule must go through to complete sperm production completely

4.5 - 5

spermatogenic wave

the sequential ordering of stages along the length of the seminiferous tubule

blood testis barrier

prevents antibodies in the blood from getting to the germ cells, first appear at puberty and induced by FSH targeting Sertoli cells

what can destroy tight junctions of Sertoli cells

heat, heavy metals, endocrine disruptors, lack of FSH or testosterone

variation of sperm production

*testis size

*efficiency of spermatogenesis

-mitotic division

-degeneration of germ cells

*length of spermatogenesis

sperm metabolism biochemistry

can be anaerobic (glycolysis) or aerobic, glucose will be phosphorated to glucose-6-phosphate by hexokinase, and fructose in seminal plasma will be phosphorated to fructose-6-phostate by hexokinase

phosphatase in sperm

futile cycle as a short term fix to maintain glucose levels in sperm, turns glucose-6-phosphate back to glucose

ATP utilization in sperm

- motility (60%)

- substrate cycling (40%) [wasted]

- maintenance of ionic gradients [very small amount]

- transcription and translation [none after condensation of nucleus and loss of residual body]

sperm metabolism

•Temperature dependent

-ATP production increases as temperature increases

•ATP dependent processes are temperature dependent

-motility increases with increasing temperature

how does sperm transport in the seminiferous tubules

bulk fluid flow, contraction of myoid cells

how does sperm transport in the rate testis

fluid flow, rete testis secretion

how does sperm transport in the epididymis

contraction

how does sperm transport in the vas efferent

fluid flow and cilia

epididymal functions

maturation, concentration, secretion, transport, storage

maturation function of epididymis

change in fertility (changes in protein on surface of sperm head), develop motility, nuclear condensation, cytoplasmic droplet

concentration function of epididymis

remove water (vas efferens, caput)

secretion function of epididymis

turns testerone to dihydrotesterone, the enzyme that converts this is 5-alphareductase, energy substrates (GPC, free fatty acids, carntitine) and glycoproteins, lipids, and enzymes

5-alphareductase

Converts testosterone to 5-alpha

hormonal control of epididymis

-absolute need for androgen

-caput- tubal testosterone

-corpus- tubal DHT, vascular testosterone

-cauda- tubal DHT, vascular testosterone

EEE=PSP

erection, emission, ejaculation is regulated by intervention of parasympathetic, sympathetic, and parasympathetic

which species have a fractionated composition of ejaculate

boar, stallion, human

components of semen

water, sperm, substrates , inorganic salts, proteins