Spermatogenesis and Male Tract Flashcards by Isabelle Bigio

What is the main morphological difference between the ovaries and the testes?

In ovaries - germ and granulosa cells found at the edges of the ovary

Testes - germ and epithelial cells cluster and form cords in the centre of the structure

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Spermatogonia are derived from ____ cells

Germ

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Sertoli cells are derived from ____ cells

Epithelial

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Descent of the testis occurs at month ____ of foetal life

7-8

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What is the influence of AMH on descent of the testes?

Controls descent from abdominal cavity to internal inguinal ring

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What is the influence of testosterone on descent of the testes?

Controls descent from internal inguinal ring to scrotal sac

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Two forms of cryptorchidism are ____ and ____

Incomplete and maldescent

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Cryptorchidism affects __% of babies at full term, and ___% of premature male babies

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Leydig cells secrete testosterone for ___ weeks onwards.

8-10

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What are the purposes of the foetal and neonatal testosterone peaks?

Foetal = programming of the hypothalamus

Neonatal = programming of the gonads (and brain tissue)

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What are the testicular changes that occur in puberty?

Marked increase in proliferation of spermatogonia
Cords develop a lumen and become seminiferous tubules
Beginning of sperm production

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How does the tail of the epididymis differ to the other components?

Foldings decrease and muscular tube becomes thicker

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How do sertoli cells appear histologically?

Triangular cells sitting on the basement membrane

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How are spermatogonia separated from spermatocytes in the testes?

Junctional complex of the sertoli cells

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The meiotic division in spermatogenesis takes approximately ___ weeks

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What are the three phases of spermiogenesis?

Golgi phase
Cap phase
Maturation phase

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It takes approx ____ days for spermatogonia to move from the basal lamina to the lumen

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It takes ___ days between successive waves of developing spermatozoa

‘Normal’ ejaculate contains ____ million sperm but highly variable, and number of motile sperm important

100-300

The pituitary is necessary for ___ and ___ of the testis

Growth and maintenance

LH acts on ____ cells in the testis whereas FSH acts on ____ cells

Leydig

Sertoli

In the fatty tissues of the body testosterone is converted to oestrogen via _____

Aromatase

Inhibin suppresses FSH/LH only

FSH

What is the effect of DHT on spermatogenesis?

Meiosis - especially prophase of 1st division
Spermatid maturation - at higher levels than for meiosis
Stimulates ABP

What effect do oestrogen/testosterone have on LH concentration and pulse frequency?

- Testosterone decreases pulse frequency | - Oestrogen decreases concentration

What are the roles of estrogen in men?

1. Negative feedback control - peripheral conversion of T to E2 2. Enhances action of androgens (fibromuscular growth)

What were the ovarian effects in aromatase knockout mice?

- Follicles develop but do not progress to ovulation - Follicles become ST-like structures by one year, develop sertoli cells w/ Tight junctions - Leydig cells develop in interstitial tissue

What were the testicular effects in aromatase knockout mice?

Interruption of spermatogenesis at early stage spermatid development

What is the hormonal abnormality in sertoli-cell only syndrome?

Lack of inhibin (-> elevated FSH)

What is the function of the bulbourethral glands?

Secrete a clear, viscous secretion into the urethra creating a low coefficient lining

Sperm maturation takes place in the epididymis for about __ weeks

What changes occur in sperm maturation?

- Residual cytoplasm absorbed - Increased formation of disulphide bonds in structural proteins - Increased surface changes - Conc increases 100x

What is the role of oestrogen in sperm maturation?

Resorption of fluid to increase sperm concentration

Which organs input into seminal fluid?

- Seminal vesicles (13-33%) - Prostate (46-80%) - Epididymis/ampullae (10%)

What is the pH and components of fluid from the seminal vesicles?

- pH 7.3 | - Fructose + prostaglandins

What occurs in the emission phase of erection and ejaculation?

Emission of semen from ducts and glands by contraction of smooth muscle

What occurs in the expulsion phase of erection and ejaculation?

Expulsion of semen by contraction of somatic muscles

The emission phase is under sympathetic/parasympathetic control whereas the expulsion phase is under sympathetic/parasympathetic control

Sympathetic | Parasympathetic

What is retrograde ejaculation?

Failure of the internal sphincter of the bladder to close during ejaculation

Which muscles are involved in the expulsion phase of ejaculation?

Bulbo-spongiosus and ischiocavernosus

What are the fractionations of ejaculate?

1. Initially a few drops of fluid from urethra and bulbourethral glands 2. Prostate-rich portion 3. Middle portion - part SV + sperm-rich fraction from epididymis/ampulle 4. Viscous portion from SV (post sperm)

Which chemicals are involved in the physiology erection?

NO and guanosine monophosphate

Which characteristics of sperm are analysed in the assessment of male infertility?

1. Liquification 2. Volume 3. Sperm concentration 4. Motility 5. Grade of motility 6. Morphology 7. Debris