Reproductive System Development

Sex

Biological traits, including genotype and phenotype sex chromosomes and physical features

Gender

Outward expression of gender (femininity, masculinity, etc)

Sexuality

Sexual attraction and activity (physical and emotional attraction)

HY antigen

(+) Found only on male cells

ZFY gene

Expressed on Y chromosome

Definitive TDF and landmark proof

SRY gene; found in Y chromosome, not expressed in XY females

Primary Sex Determination

Development of gonads; occurs in fetus

Secondary Sex Determination

Development of secondary sex traits (physical characteristics)

Genital Ridge

Can be seen at 4 weeks; develops from intermediate mesoderm adjacent to kidneys; biopotential till week 8

Primordial Germ Cells

Seen in human yolk sac at 4 weeks, migrate to mesoderm of posterior body wall where they induce maturation of genital ridge

How do testes develop?

Expression of SRY gene causes ridge to differentiate in tests

How do ovaries develop?

If no SRY gene, ridge defaults to differentiate into ovaries

Wolffian Duct

Carries urine from second embryonic kidney

Müllerian Duct

Forms lateral to the Wolffian Ducts

What is the role of Sertoli cells is testes development?

• Secrete Müllerian inhibiting substance causing Müllerian ducts to degenerate

• Stimulate Leydig cells to produce testosterone allowing Wolffian ducts to continue growing

• Gives rise to the efferent ductules, epididymis, vas deferens, and seminal vesicle