Sex Determination Gametogenesis Male Reproduction Part 1: Chapter 26

Outline (part I) Sex determination (male versus female fetus) sry gene Hormonal control Wolfiann ducts Mullerian ducts Gametogenesis Timing of gamete production Basic patterns of hypothalamic and gonadal hormone secretions Male reproduction Major structures Maturation and passage of spermatozoa Miracle of Life (film)

Sexual Differentiation 2nd month of development

Initially Bi-potential… Gonads Internal genitalia External genitalia or

Bi potential internal genitalia Wolffian ducts develop into: Seminal vesicles Vas deferens epididymis Fetal (male) Sertoli Cells secrete anti-Muellerian substance Müllerian ducts Directed by testosterone (Leydig Cells of fetal testes) Inhibits Müllerian ducts

Testosterone and MIS Internal Genitalia

Binds to DNA and Gonad Differentiation MALES SRY GENE Testis Determination Factor Binds to DNA and Gonad Differentiation

Binds to DNA and Gonad Differentiation FEMALES NO SRY GENE! I don’t have an SRY gene. NO! Testis Determination Factor NO Binds to DNA and Gonad Differentiation

The timing of gametogenesis In males In females

Fertilization and the second meiotic division Fertilization of an ovum

Male Reproduction and Spermatogenesis

Male Reproductive Tract

Cryptochidism: failure of testes to descend

epididymis TESTIS

Will now look at the structure and function of this region

Responds to LH Responds to FSH 64 days

Sertoli Cells Sertoli Cells Nourish developing sperm Secretes Inhibin Androgen Binding Proteins

Cells of Leydig Cells of Leydig Produce testosterone

12 more days!

Parasympathetic (term relevant to autonomic nervous system that we will discuss when we begin the nervous system.

Ejaculation 200,000,000 sperm!! sympathetic nervous system Muscular contraction associated with event termed orgasm. 200,000,000 sperm!!

Review: Polygenic Disorder Klinefelter Syndrome

Review: Polygenic Disorder

Onto Female Reproduction