Testicular Function and Spermatogenesis

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Questions and Answers

What is the primary hormone that stimulates the production of testosterone in the testis?

Gonadotropin-Releasing Hormone (GnRH)

Luteinizing Hormone (LH) (correct)

Follicle Stimulating Hormone (FSH)

Prolactin

Which structure is responsible for the mature passage of sperm from the testis?

Vas deferens

Seminiferous tubules

Seminal vesicles

Epididymis (correct)

In the process of spermatogenesis, which hormone inhibits the release of luteinizing hormone (LH)?

Testosterone (correct)

Inhibin

Follicle Stimulating Hormone (FSH)

Estrogen

What role do Leydig cells primarily play in testicular function?

They release testosterone. Signup and view all the answers

What is one of the effects of tight-fitting underwear on spermatogenesis?

It adversely affects the formation of mature spermatids. Signup and view all the answers

What is the primary function of the testis?

Spermatogenesis and testosterone secretion Signup and view all the answers

Which process is primarily initiated by testosterone in the male reproductive system?

Spermatogenesis Signup and view all the answers

What role do the seminal vesicles play in male reproduction?

Provide nutrients and factors for seminal fluid Signup and view all the answers

In the hypothalamic-pituitary-gonadal (HPG) axis, which hormone is primarily responsible for stimulating the release of FSH and LH?

Gonadotropin-releasing hormone (GnRH) Signup and view all the answers

What is the effect of inhibin in the male reproductive system?

Inhibits FSH production Signup and view all the answers

What is a significant factor secreted by the prostate gland?

Alkaline fluid Signup and view all the answers

Which gland is primarily responsible for secreting mucus for lubrication during ejaculation?

Bulbourethral gland Signup and view all the answers

What effect does testosterone have on spermatogenesis?

It promotes spermatogenesis Signup and view all the answers

How does the presence of aromatase in adipose tissue affect male reproductive health?

Can lead to feminizing effects due to increased estrogen production Signup and view all the answers

What is the main action of dihydrotestosterone (DHT) in male physiology?

Enhance male secondary sexual characteristics Signup and view all the answers

What is the primary role of testosterone in spermatogenesis?

Stimulates mitosis and meiosis Signup and view all the answers

What is produced during the first meiotic division of primary spermatocytes?

Two secondary spermatocytes Signup and view all the answers

What significant change occurs to spermatids during spermatogenesis?

Maturation into motile spermatozoa Signup and view all the answers

What hormone influences the extensive remodeling of spermatids?

Follicle-stimulating hormone (FSH) Signup and view all the answers

Which structure in sperm contains genetic material and enzymes for penetrating the ovum?

Head Signup and view all the answers

What is the role of the epididymis in sperm maturation?

Fluid absorption to concentrate sperm Signup and view all the answers

Which glands supply the majority of the fluid content in semen?

Seminal vesicles Signup and view all the answers

What is the function of the buffers in semen?

Neutralizing acidic environments Signup and view all the answers

What component of semen is primarily produced by the prostate gland?

Prostaglandins Signup and view all the answers

Where are sperm stored after leaving the epididymis?

Vas deferens Signup and view all the answers

What do primary spermatocytes theoretically produce in terms of spermatids?

4 spermatids Signup and view all the answers

What does the tail of the sperm do?

Facilitates sperm mobility Signup and view all the answers

What type of cells produce testosterone in the testis?

Leydig cells Signup and view all the answers

How does FSH affect the development of spermatids?

Promotes extensive remodeling and cytosol removal Signup and view all the answers

Study Notes

Testicular Function: Spermatogenesis

Spermatogenesis occurs in seminiferous tubules of the testes.
Testosterone is crucial for both mitosis and meiosis during sperm production.
Mitotic proliferation begins with spermatogonia, where one daughter cell maintains the germ cell line and the other moves toward the lumen to develop into spermatozoa.
Primary spermatocytes, formed from spermatogonia, undergo meiosis to yield four spermatids, each with 23 chromosomes.
Each primary spermatocyte produces two secondary spermatocytes during meiosis, which further differentiate into spermatids.

Spermatids to Spermatozoa Transformation

Spermatids undergo extensive remodeling under the influence of FSH, transforming into spermatozoa by removing excess cytosol and organelles.
Mature spermatozoa contain 23 single-stranded chromosomes and are primarily energy-dependent, utilizing mitochondria for motility.
Half of the sperm carry an X chromosome and the other half a Y chromosome, influencing the sex of the offspring.

Spermatozoa Structure and Function

The sperm head houses the nucleus and an acrosome, which is crucial for penetrating the ovum.
Acrosomal enzymes are inactive until sperm contact occurs with the egg, allowing effective fertilization.
The tail facilitates movement, powered by mitochondria situated in the midpiece for energy.

Maturation of Spermatozoa

Sperm exiting the testes are initially non-motile and non-fertile but mature in the epididymis over 24 hours with the help of testosterone.
Sperm concentration increases as fluid absorption occurs in the epididymis.
Defensins released in the epididymis enhance sperm motility and provide protection against microorganisms.
Sperm are transported to the vas deferens, where they are stored and receive nourishment from secretions.

Accessory Glands

Seminal vesicles contribute the majority of semen volume, providing fructose and prostaglandins that aid in sperm motility.
The prostate gland secretes an alkaline fluid that neutralizes acidity and includes PSA for semen clot degradation.
Bulbourethral glands add mucus to the urethra for lubrication during ejaculation.

Components of Semen

Semen consists of approximately 180 million sperm in a volume of 2.75 ml, alongside mucus, buffers to neutralize vaginal acidity, and nutrients.

Hormonal Control of Spermatogenesis

Leydig cells within the testes secrete testosterone; LH stimulates this production.
FSH promotes spermatogenesis by acting on Sertoli cells, which support developing sperm.
Feedback mechanisms are in place: testosterone inhibits LH and GnRH production.

Testosterone and Its Effects

Aromatase, found in adipose tissue, converts testosterone to oestradiol, potentially leading to feminizing effects in obese males.
Oestradiol is significant for spermatogenesis and bone health, including epiphyseal plate closure.
Exogenous testosterone can disrupt normal hormonal balance and potentially cause negative feedback inhibition of natural testosterone production.

Summary of Male Reproductive Endocrinology

Pulsatile release of gonadotropin-releasing hormone from the hypothalamus stimulates the anterior pituitary to secrete FSH and LH.
Testosterone exerts various actions throughout the body, including potential influences on breast development due to estrogenic effects.

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Description

This quiz explores the process of spermatogenesis, focusing on the mitotic proliferation occurring in the seminiferous tubules. It emphasizes the role of testosterone in both mitosis and meiosis as essential for sperm production.