2 - Male Reproduction

Describe the major compartments and cells of the testis and their functions

SEMINIFEROUS TUBULES:

• contain sperm cells and SERTOLI CELLS

• Sperm production

• Sertoli cells: Nurse Cells

INTERSTIAL COMPARTMENT

• Neuronal and vascular elements

• Connective tissues, immune and LEYDIG CELLS

• Testosterone production

• LEYDIG CELLS: steroidogenic produce hormones

What are the Sertoli and Leydig cells, what do they produce.

SERTOLI CELLS:

• Maintain blood-testis-barrier

• Secrete testicular fluid for transport of immobile sperm towards epididymis

• Produces Androgen-binding proteins (ABP)

• Produces Inhibin

LEYDIG CELLS

• produces testosterone

Describe the different stages of sperm production (spermatogenesis) and understand the role of spermiogenesis

SPERMATOGENESIS:

The process of producing sperm cells from spermatogonia in the seminiferous tubules of the testes

Stages of Spermatogenesis -

1. Mitosis - spermatogonia → primary spermatocytes

2. Meiosis - primary spermatocytes —(meiosis I)→secondary spermatocytes -(meiosis II)→ spermatids

3. Spermatogenesis - spermatids → sperm/spermatoza

What is Spermatogenesis?

• the final stage where spermatids differentiate into mature sperm, developing a head, acrosome, midpiece and flagellum. No cell division occurs

What are the major differences between Spermatogenesis and Oogenesis

SPERMATOGENESIS:

• begins at puberty

• Produces sperm continuously

• One primary spermocyte → 4 sperm

• Produces many gametes

• Generally continues throughout adult life

OOGENESIS

• begins before birth

• Produces/recruits oocytes cyclically

• One primary oocyte → 1 ovum + polar bodies

• Limited number of oocytes

• Ends at menopause

Describe the Testosterone Feedback Loops - What stimulates it, How is it regulated.

What stimulates testosterone Production:

• GnRH from hypothalamus → LH from the anterior pituitary → LEYDIG cells → testrosterone.

How does T regulate itself:

• Inhibin B from Sertoli cells provide negative feedback on FSH

Simple Pathway:

Hypothalamus → GnRH → Anterior Pituitary → LH → Leydig Cells → Testosterone → negative feedback

Describe how T changes throughout the life-course

List the Major functions of male hormones in the reproductive tract and elsewhere in the body

On Reproductive Organs:

• Development and maintenance of male reproductive organs

• Supports sperm production

• Support sex drive

• Helps maintain reproductive function

Elsewhere in the Body:

• Promotes muscle and bone growth

• Contributes to male-pattern hair growth

• Supports red blood cell production

• Contributes to changes in voice during puberty

Describe the role of androgen binding protein (ABP) in the testis and where is it produced?

What is ABP?

• a protein that binds testosterone and DHT, keeping their concentration high inside the seminiferous tubules

Why is ABP important?

• Helps maintain the high androgen concentration needed for spermatogenesis

Where is ABP produced?

• by Sertoli cells in the seminiferous tubules

What stimulates ABP production?

• FSH and Testosterone