This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endometriosis and Infertility, Subject name: Gynaecology & Obstetrics
The cells which lie outside blood testis barrier: 
Select and explain. 
A. Sertoli cells, B. Spermatocyte, C. Spermatid, D. Leydig cells
D: Leydig cells
Answer: D: Leydig cells 
Explanation: Ans. is d, i.e. Leydig cellsBlood testis barrier is formed by Sertoli cells which keeps the growing germ cells (its all stages) separated from blood.