MALE 



_ .MESENCHYME 



9,0 



LEFT GONAD 



LEFT TESTIS 



>o^ y r vn m .J » 



@ 1 SEMINIFEROUS 7 



®/' TUBULES / 



// 1 



CORTEX DISAPPEARS V 



RIGHT GONAD 



FEMALE 



q ° Qt ^ MESENCHYME 



LEFT GONAD 



MEDULLA 



CORTEX 



LARGE 

 FUNCTIONAL 

 LEFT OVARY. 



OOCYTES 



CORTEX FORMS 

 FOLLICLES 



RIGHT GONAD 



SMALL 

 RUDIMENTARY 

 IT GONAD 



SOME CORTEX 

 MAY REMAIN 



MEDULLA 

 FAILS TO 

 DIFFERENTIATE 



MEDULLA REPRESSED 

 Fig. 193. Top: Right and left gonads of male contain both cortex and 

 medulla. The testes develop from the gonad by a differentiation of the medulla. 

 The cortex disappears. Bottom: Right and left gonads of female contain both 

 cortex and medulla. The left ovary results from a growth and differentiation of 

 the cortex, while the medulla is repressed. The right gonad fails to form an ovary 

 but remains in a rudimentary condition with a medulla and usually some cortex. 



301 



