Spermatogonia are formed after which cell division?

Which of the following structures represents the completion of the first meiotic division?

Which of the following undergoes the $Meiosis-I$ division?

Given a diagram showing a portion of a seminiferous tubule. Identify the marked alphabets.

Which part of the sperm helps in penetrating the egg membrane?

If two primary spermatocytes and two primary oocytes undergo meiosis simultaneously,what will be the ratio of spermatozoa and ova produced at the end of the gametogenesis?