Spermatogenesis and Male Tract Flashcards
Male gonadal cell types and origin
testis descend when?
Spermatogonia: Germ cell
Sertoli cell: epithelial
Leydig: interstitial tissue
Myoid: “
7-8th month fetal life
Cryptorchidism
Failure of testes to descend. Causes infertility (high temp) Incomplete and maldescent
How do testosterone levels change in early development until puberty?
Leydig cells produce from weeks 8-10.
Fetal peak, then drops. ‘Brain programming’
Neo-natal peak: ‘Gonad programming’
Pre-pubertal: virtually none
Pubertal: Raises
What happens at puberty?
Marked increase in proliferation of spermatagonia.
Cords develops seminiferous tubules
Sperm production commences
Overview of testis tract
ST’s to rete testis to epididymis to vas deferens
Spermatogenesis.
The change of spermatagonia to spermatazoa by spermatocytogenesis, meiosis and spermiogenesis
Sertoli cell features
Envelop germ cells. Have tight junctions to separate spermatagonia from spermatocytes (immune protection)
Spermatocytogenesis
_____ (on basal lamina), _divide. One remains as stem cell, one continues and these proliferate by mitosis and move through Sertoli junctions
Spermatogonia (on basal lamina), 2n divide. One remains as stem cell, one continues and these proliferate by mitosis and move through Sertoli junctions
Meiosis 1 and 2
1: After passing the _____ ____, ____ spermatocytes. Are ____. The process is ____
After meiosis 1, are now _____ spermatocytes. These are _____. Short half life. Meiosis 2 occurs to form ____ (also haploid)
1: After junctional complex, Primary spermatocytes. Are large. The process is slow
After meiosis 1, are now secondary spermatocytes. These are haploid. Short half life. Meiosis 2 occurs to form spermatids (also haploid)
Spermiogenesis (forms spermatozoa)
Golgi phase: On one end, Golgi apparatus forms vesicles, proacrosomal granules.
Cap phase: Vesicles fuse to form acrosome, sits on top of nucleus
Acrosomal: elongates
Maturation
What is the cycle of the ST’s? (how long does it take a spermatogonia to reach etc)
about 74 days
Spermatozoa are released in waves due to during spermatogenesis are always linked.
At any one point production is discontinuous by collectively continuous. About 300-600 sperm/second/g of tissue. 100-150million per day. Ejaculate 150-300 million
Hormonal control of spermatogenesis (diagram (33)? go through all the hormones)
GnRH: causes FSH and LH release
LH: targets LEYDIG cells. Causes T production.
FSH: Targets Sertoli cells, which produce inhibin, ABP and other proteins.
T: Has many fates. Plasma T acts on target organs such as the epididymis, prostate, seminal vesicles; Negative feedback (GnRH, LH); Turns into DHT (plasma and local area effects); Sertoli cell, turns into DHT or E2.
E2: prepubertal E from sertoli cells, rest from plasma T. so Neg feebcack.
ABP: Binds to T and DHT to concentrate in ST’s. T goes to germ cells and the ST lumen.
Inhibin: neg feedback on FSH
Effect of T and DHT on spermatogenesis
Need for meiosis (1st division); spermatid maturation; stimulates ABP.
Role of E2 in males
Negative feedback
Enhances action of androgens e.g induces fibromuscular growth, needed for spermatogenesis
Male tract things for me to take note
Ejaculatory duct, where seminal vesicle emptys contents (within prostate)
utricle where prostate empties contents
Cowpers/Bulbourethral glands: ant to prostate
Glands of Littre line urethra
Sperm Maturation where and what happens
Epididymis (1-21 days)
Increased disulphide bonds formed. Increases stiffness and ability to swim
Concentrates by absorbing water
Semen constituents and fraction.
Seminal fluid vs prostatic
Spermatozoa 10, seminal 10-30 and prostatic fluid 45-80
Seminal: fructose, PG’s, pH 7.3 white part
Prostatic: acid phosphatatse, citric acid, spermine pH 6.5
What are the two phases of ejaculation
Emission: emission of semen from ducts and gland, by smooth muscle. Sympathetic control
Expulsion: Movement of semen out by contraction of somatic muscle bulbospongiosus and ischiocavernosus. Parasympathetic control
Fractionation of ejaculate
1) fluid from bulbourethral and Litre glands
2) presperm, prostatic rich portion
3) Middle portion: SV plus sperm rich from epididymis/ampulla
4) viscous part from SV
Neural control of ejaculation
1) Sensory stimulus received and travels to the ____ centre at __.
2) The erigentes nerve (_________) causes ________/SM relaxation of the penis/ clitoris and labium min.
3) This sensory information is taken to the _______ centre at ___ and the erection centre.
4) First, the hypogastric nerve (____________) from __ travels to the SV’s, _______, vas deferens and _____ ___ _______ ______ to causes SM contraction. This is ________.
5) The ________ nerve (___________) causes the somatic muscles bulbospongiosus, ischiocavernosus and the _____ _____ ______ to contract. This is ______
1) erection; S2
2) parasympathetic; vasodilation
3) ejaculation; L1;
4) Sympathetic; L1; Prosate; internal bladder sphincter; emission
5) pudendal; parasympathetic; external urethral sphincter expulsion
Male infertility assessment
Liquification- should occur in 15min Volume <1ml bad Sperm conc <1.5 million/mL bad Motility percent of active sperm > 40% Motility Grade good/moderate forward progess, poor, twitching Morphology Debris e.g WBC's in them is bad
3 or more sub optimum, will struggle
Also Testosterone levels, frequency of emission and temperature
Male infertility assessment
Think about semen and sperm things to look at
Liquification- should occur in 15min Volume <1ml bad Sperm conc <1.5 million/mL bad Motility percent of active sperm > 40% Motility Grade good/moderate forward progess, poor, twitching Morphology Debris e.g WBC's in them is bad
3 or more sub optimum, will struggle
Also Testosterone levels, frequency of emission and temperature
