11.4 HUMAN

REPRODUCTION –

PART II

IB BIOLOGY

QUICK REVIEW -

OOGENESIS

OOGENESIS OUTLINE

• Begins during fetal development, when oogonia are formed by mitosis before undergoing a period of growth

• These cells begin meiosis but are arrested in prophase I until puberty

• At puberty, some follicles continue to develop each month is response to FSH secretion

• Follicles complete the 1st meiotic division to form 2 cells of unequal size (secondary ooctye + polar body)

• Secondary oocyte begins 2nd meiotic division but is arrested in prophase II (until fertilisation)

• It is released from the ovary, and if fertilisation occurs, will complete meiosis

• 2nd meiotic division will produce an ovum and a second polar body

SPERMATOGENESIS

AND OOGENESIS

Similarities:

- Both processes result in the formation of haploid gametes

- Both processes involve mitosis, growth and meiosis

Differences:

SO YOU’VE

FERTILIZED AN EGG…

EMBRYO

DEVELOPMENT

3 Main Preliminary Stages:

1. Zygote

2. Morula

3. Blastocyst

EMBRYO

DEVELOPMENT

HORMONAL CONTROL

OF PREGNANCY

HCG hormone