(a) About 300 million spermatozoa may be present in a human male ejaculation at one time. Calculate how many spermatocytes

Question

With reference to the above schematic representation of (a) Spermatogenesis and (b) Oogenesis answer the following questions: 

(a) About 300 million spermatozoa may be present in a human male ejaculation at one time. Calculate how many spermatocytes will be involved to produce 300 spermatozoa. 

(b) How many chromatids are found during Oogenesis in

(i)  Primary oocyte and 

(ii)  First polar body in a human female?

Answer 1

(a)  Each primary spermatocyte will undergo meiosis-I and meiosis-2 which will result in 4 spermatozoa

300 million/4 = 75 million

(b)  Since replication has occurred by this stage

46 x 2 = 92 chromatids 

Meiosis –I is completed by this time 92/2 = 46 chromatids