male repro

what are the 2 functions of hte testis

• production of spermatozoa

• production of reproductive hormones

spermatogenesis

• 2 types of division ad what do they produce

• last step and what does it form

• mitotis proliferation- produces large numbers of cells (spermatogonia), diploid and genetically identical

• meiotic division- generates genetic diversity as chromatids exchange genetic material, halves chomosome number (haploid), spermatocytes to spermatids

• cytodifferentiation(spermiogensis)- packages genes for delivery to oocyte, elongating spermatids→spermatozoa

spermatogenesis

sertoli cells

• what attaches to it

• what does it control and how

• what does it do to elongating spermatids

• what does it mediate

• what are they linked by and why

• developing sperm attach to sertoli cells via gap junctions

  • sertoli cells control spermatogenesis-

  • transfer developmental proteins to spermatocytes

  • remove material from elongating spermatids

  • mediate androgen hormone (testosterone) action

• all sertoli cells are linked by gap junctions = coordinated wave of spermatogenesis

transport to epididymis

• where are they first released

• where do they then travel to

• sperm released from associated sertoli cells into semifumerous tubules.

• sperm transported in fluid by sertoli cells

• travel into rete testis, vasa efferntia and epididymis

epiddymal maturation

• Sperm maturation

• Loss of surplus cytoplasm (cytoplasmic droplet)

• Condensation of nuclear chromatin by disulphide bridge

• Metabolism

• Decreased metabolic activity to prolong cell viability

• Increased dependence on external fructose for energy production

• Motility

• Increase in cAMP and acquisition of motlity

Passage through epididymis takes 10 days

Journey through the urethra – seminal plasma Seminal plasma + spermatozoa = ejaculate/semen

where is seminal plasma derived from

• accessory glands

• prostate glands

• seminal vesicle

• ampulla

• bulbourethral gland

what does seminal plasma do

• determines ejaculate volume

• accessory gland structure varies between species

• carries spermatozoa

seminal plasma composition

Glycoprotein decapacitation factors

• Fructose and Sorbitol

• energy substrate

• Citric acid

• prevents cell coagulation - seminal ’stones’

• Acid phosphatase

• phospholipid metabolism

• Buffers

• neutralise acid pH of vaginal fluids

• Ascorbic acid

• anti-oxidant after ejaculation

• Prostaglandins

• muscle contractions in female reproductive tract

androgens

• main testicular is testosterone

• sunthesised by leydig cells

• testosterne passed from leydig cells into blood (feedback on anteriori pituitayr and hyothalamus) and semifumerous tubules

• sertoli cells convert testosterone to dihydrotestosterone wich passes into testicular fluuid to suport speratogenesis.

hypothalamic pituitary axis

• what are pituitary hormones major regulators of

• how is GnRH transported to the anterior pituitary

pituitary hormones are major regulators of spermatogenesis

GnRH is synthesised in the hypothalamus

GnRH is transported to anterior pituitary via the blood hypophyseal portalvessles - mediating the sectretion of LH and FSH

why castrate

• Removal of the testis

• Stops sperm production

• Stops testosterone production

• Enables lambs/piglets to grow larger before slaughter– Testosterone affects taste

• Reproductive and behavioural purpose

because men are dicks

spermatic cord

• Artery

• Veins

• Vas deferens

• Nerves

• Cremaster muscle (paired muscle in the inguinal canal and scrotum covering the testis and spermatic cord)

• Enters abdominal cavity through the inguinal ring

blood supply

• testicular artery

• r testicular vein

• left testicular vein

• what are vessels arranged as

• Testicular artery – aorta (below renal artery)

• Right Testicular vein – inferior vena cava

• Left Testicular Vein – left renal vein

• Vessels arranged as Pampiniform plexus

• Counter current temperature regulation

fibroelastic penis

• what animal

• what type of tissue

• components

• Ram, bull, boar

• Erectile tissue

• Corpus cavernosum

• Corpus spongiosum

• Sigmoid flexure

• Allows penis to be retracted into the body until erection

• Sigmoid flexure held by retractor penis muscles

• Relax retractor muscles penis protrudes

musculovascular penis

• what species

• features

• differences

• what type of penis muscle

Stallion, Human

• Large corpus cavernosum fills with blood during erection. Cavernous tissue contains large blood spaces divided by a thin septa. therefore a relatively larger volume of blood is required to achieve erection.

• No sigmoid flexure

• Retractor penis muscle

• lots of erectile tissue and little connective tissue so during erection there is both an increase in length and diater of the penis

glans penis

• Highly specialised!

• Tom cat androgen dependent spines. cone shaped with keratinised papillae directed caudally.

• induced ovulator

• Boar corkscrew with a left hand thread.

• Ram large extension of the urethral process

• bull - slightly spiralled end

• stallion- mushroom shape with slight protrusion of the urethral process

visual cues

• mating in others

• lordosis

olfacoty cues

• Sniffing of vulva • Female urination • Pheromones • Androgens, Boar Mate

erection

• what is it

• what happens to the arteries

• what happens to the penis muscle and why

• what happens to the muscle of the vas deferens, seminal vesicles and prostate

• what is expelled

Erection– Stimulation of pelvic nerve

• Arterial dilation and increased blood flow

• Relaxation of retractor penis muscle– Straightens sigmoid flexure

• Muscles of vas deferens, seminal vesicles and prostate contract

• Spermatozoa and seminal plasma expelled

• Can be very forceful in some species (Stallion)

• Single spurt (bull 1-3sec) or extended (camel 6-20min

blood pressure

1. flaccid penis, low blood pressure

2. sexual arousal, vasodilation of helicine arteries and increasing blood flow, increase in pressure

3. increased blood flow to cavernous tissue and decreased venous outflow, sharp increase

4. sharp decrease, venouss outflow

erection in dogs

Male and female ‘tied’

• Os penis

• Bulbus glandis forms copulatory lock

• Venous outflow restricted

• Muscles in female vulva contract

copulation in dog

• First stage coitus

• Male mounts female

• First and second fractions of semen ejaculated

• 1-2min

• The Turn

• Dog turns by lifting one leg over bitch

• Second stage coitus

• Third fraction of semen ejaculated (30ml) wow so exact

• 5-45min (45 min!?? so long)

• Inter-uterine deposition

• Maintains high vaginal pressure