11.4 Sexual reproduction

Describe the different cell types in the seminiferous tubules that are involved in the process of spermatogenesis (4)

Spermatogonia are undifferentiated cells which mature and divide by mitosis into primary spermatocytes. Primary spermatocytes divide by meiosis I into secondary spermatocytes. Secondary spermatocytes divide by meiosis II into spermatids. Spermatids differentiate into spermatozoa. Sertoli cells provide support to these developing cells. Leydig cells produce testosterone.

What helps to prevent polyspermy? (1)

The cortical reaction

Compare and contrast the processes of spermatogenesis and oogenesis (8)

The similarities of spermatogenesis and oogenesis are that both involve mitosis at the start. Both also results in haploid gametes. Both involve two divisions of meiosis. Both are stimulated by hormones. The differences are that oogenesis occurs in the ovaries while spermatogenesis occurs in the testes. Oogenesis starts during embryo development while spermatogenesis starts during puberty. Oogenesis pauses occur in prophase I while there are no pauses in spermatogenesis. Oogenesis has large quantity of cytoplasms in egg while spermatogenesis has small quantity of cytoplasm. Oogenesis stops at menopause while spermatogenesis goes on until death.

What does the blastocyst secrete? (1)

hCG