Repro System: part 1 - Males

What commonalities are found between sexes?

1. Formation of gametes

2. Hypothalamic/pituitary control of reproduction

Gametogenesis

• what is gametes

  • How many chromosomes

  • Produced from what organ system

  • Produced from initial what cells with how many chromosomes

• What process goes it involves

  • Two options: what is the better one

Gametes with 23 chromosomes are produced from cells in the gonads (name for the entire system in both men and women) with 46 chromosomes

Process involves Meiosis

Mitosis vs Meiosis

• explain the differences

Process involves Meiosis

• DNA replicated once

• Cells undergo division twice

• Meiosis 1 and meiosis 2

• Random assortment possible (non-homologous recombination)

In contrast: Mitosis = normal cell division

• DNA replicated once

• Cells undergo division once

• Found in somatic cells

Hypothalamic/pituitary control of reproduction

• What does the hypothalmic produce what hormone

• What does the pituitary produce what two hormones

  • What is the function of both hormones

• CNS detects internal and external stimuli

• GnRH = gonadotropin-releasing hormone

  • Produced by the hypothalamus

• LH = Luteinizing hormone and FSH = Follicle-stimulating hormones

  • Produced by the anterior pituitary gland

  • LH triggers the endocrine cells to produce steroid and peptide cells

    • The steroid and peptide cells help in the production of gamates

    • In females also directs involved in gamete production

  • FSH directly affects the reproduction glands (testes/ovaries) for gamete production

GnRH

• secretion patterns

  • Purpose

  • Changes in what type of stages in life

• What type of frequency for LH productions, what type of frequency for FSH productions

• Produced by what cells

• Produced in what gland

• Regulated by what two things

• GnRH secreted in pulses from neuroendocrine cells in hypothalamus

  • Low freq = FSH release

  • High freq = LH release

• Pulsatility critical for reproductive function

• Regulated by hormonal feedback and higher brain centres

• Pulse frequency/amplitude changes during development

Common male reproductive system

• Sex chromosome letters

• What is the main part for sperm production

• Why is the urethra unique in males

• for XY

• Main part: the testis

• Urthera is connected by the reproductive system and the urinart system

Sperm production process

• Produced in which part of the reproductive organ in males

  • Only explain the initial part of this where the sperm gets produce \

• Temp for optimal production and what part of the testis help with this

• How many days to produce

• How many produced in a day

• Where does it further mature

• Produced in testis

  • Initially in the seminiferous tubule

• The scrotal cavity allows for the optimal at 2-3ºC lower than body temp

• Takes ~64 days

• 200 million/day

• Further mature in epididymis structures

2 types of cell tissue in the testis

• location of each cell

• Function of each cell

Also indicate what is the precursor of sperm

• Sertoli cells (sustentacular cells) -- Support sperm development

• Leydig cells (interstitial cells) -- Secrete testosterone

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precursor of sperm: spermatogonium

Tight junctions in testis

• Function

• What cell creates them

• blood-testis barrier

  • Prevents the immune system that identifies foreign cells (e.g. the sperm cells that are only haploids with unique structures) from killing the sperm cells

• Sertoli cells form the tight junctions

Spermatogenesis

• time when formed

• What stays behind and for what purpose

• Spermatogonium produced during fetal development

• Formed during fetal development to form two spermatogonium

• Following mitosis, one spermatogonium stays to produce more

• The one spermatogonium goes through the tight junction (blood-testis barrier)

• The other cell begins to undergo meiosis forming spermatocytes

• Four spermatids produced from one starting cell

• Spermatids mature into spermatozoa

• Lose cytoplasm and gain a tail (This is called spermiogenesis)

• Pinches outwards away from the seminiferous tubules

Summary

• one serotonin cell → two spermatogonium → primary spermatocyte (one cell to undergo meiosis 1) → secondary spermatocytes (two cells undergo meisis 2) → spermatids → spermatozoa (loss cytoplasm + get tail) (the matured sperm cell)

Spermatozoa

• what is close to the head (What is it called)

• Origins of the area

  • Contains what

• Produces what three things

  • 2 with common function

  • 3rd with other function

• What does the mitochondrial spiral do?

Acrosome

• derived from the Golgi apparatus (origins) and containers enzymes

• contains hyaluronidase and acrosin which breakdown the the zona pellucida, a glycoprotein coat that covers the oocyte

• mitochondrial spiral: sperm movement

What is in semen?

• Three main accessory glands

  • (what type of gland are they)

  • How many of each gland

• Main thing for production

• What is the lubricant

• What is the buffer

• Four nutrients

• 3 other things (common things you would expect in the semen)

• Prostaglandins

  • Main function

Spermatozoa (1%) + secretions of accessory glands

• Accessory glands - exocrine glands (do not produce hormones)

  • Seminal vesicle - 2

  • Prostate gland - 1

  • Bulbourethral gland - 2

• Water

• Lubricant: Mucous

• Buffers: Neutralize acid - secreted by the bulbourethral gland

  • This is because the urthera is connected b

• Nutrients: - energy for sperm movement

  • Fructose

  • Citric acid

  • Vitamin C

  • Carnitine

• Enzymes

• Zinc

• Prostaglandins: Smooth muscle contraction - move the semen outwards

Hormonal control in males

• two hormones involved

• What stimulates the production of the hormone (what cell tissue is involved)

• What exactly doss each hormone regulate (explain the negative feedback)

• Explain the pathways (but not that important)

Inhibin

• GnRH

• FSH

• 2nd messengers

• Stimulates the serotonin cells

• Inhibin is produced

  • then inhibits FSH production only

  • Support sperm development

  • Secretes androgen-binding proteins

    • Concentrates the androgen in the testis

Testosterone

• LH affects leading cells

• Results in the production of T (testosterone)

• Inhibits the production of GnR, LH, and FSH

Testosterone secretion throughout lifE

• more testosterone produced in adults life For reproduction

• Decrease later through age

Anatomical changes and serum hormone levels in common XY

what are common patterns for hormones?

How does the testis increase in volume?

• testosterone patterns

• LH and FSH follows the testosterone patterns as well

• Increase in germ cells = increase in volume in the testis

Clinical Application: Hypogonadism

• what does it decrease

• What hormones are affected (3)

• Primary hhypoganadism

  • Main effect

  • How does it affect the other hormones

• Secondary hypogonadism

  • Main effect where

  • How does it affect the other hormones

  • Possible solution

    • Possible issue with the solution

Hypogonadism in XY

• decreased functional activity of the testes

• decreased production of androgens, inhibin B, AMH and/or impaired sperm production

Primary hypogonadism

• main effect at the testis

• Decreases testosterone

• Therefore, increase LH and FSH production (because there is no negative control system)

Secondary hypogonadism

• main effect at the brain CNS

• Which decreases GnRH

• Which then decreases the LH, FSH, and testosterone

• Solution

  • Add exogenous testosterone

  • However the decrease in LH and FSH is also a problem because you need them for fertilization purposes

    • Increase in LH and FSH is better

What type of hormone is testoserone

• made from what precursor

• steroid hormone

• Made from the cholesterol precursor and then progesterone

• Testogerone also gets converted into DHT

What does testosterone and other steroids do?

• One common thing

• what is another issue? (2 parts)

• maintains spermatogensis

• maintains and stimulates secretion from prostate and seminal vesicles

• maintains the reproductive tract

• negative effects on GnRH, LH, and FSH

• Results in baldness in males and sometimes enlargement of the prostate gland

• promoting muscle growth and therefore promoting protein synthesis and erythropoiesis (making of more blood)

• increase sebaceous gland secretion

• increase aggression

What is DHT involved in?

• increasing the size of the prostate gland

• affects baldness

What is used to treat benign prostate enlargement and male pattern baldness

• 5a-reductase inhibitor (Finasteride) used for the treatment of the enlargement for the prostate - prevents the testosterone from being converted into DHT and affected the prostate tissue

• Also helps with better hair growth

• A.k.a Propecia

• Side effects: depression, libido, fatigue