Development of sex cells

The formation of sex cells begins before birth; spermatozoa form in males and oocytes in females. Spermatogenesis (sperm cell production) occurs in the seminiferous tubules. Spermatogonia (stem cells) line these tubules at birth and contain 46 chromosomes (genetic material). After birth, spermatogonia continue to divide during mitosis. This cell division process produces two daughter cells with the same chromosome number (46) as the parent.

At puberty onset, some spermatozoa grow to become primary spermatocytes. These cells undergo meiosis, the cell division process that cuts back the number of chromosomes from 46 to 23. Each primary spermatocyte undergoes the first meiotic division to produce two secondary spermatocytes. Each secondary spermatocyte undergoes the second meiotic division to produce two spermatids. Each spermatid develops into a mature spermatozoon (sperm cell). In this way, meiosis produces millions of sperm every day.

Oogenesis is the formation of the ovum (female sex cells), which begin as hundreds of thousands of oogonia (stem cells) in the fetal ovaries. During prenatal development, the oogonia grow to become primary oocytes that contain 46 chromosomes. Each oocyte undergoes meiosis; at birth, oocytes are in prophase. During this first meiotic division, oocytes enter a resting phase that lasts until the oocyte resumes development during the ovarian cycle (puberty). The female is born with all the oocytes she will ever have.

Answer the questions

What are male and female gonads?

Where does sperm production occur?

What are the parts of a sperm cell?

What is an approximate number of sperm cells in one ejaculation?

What happens with sperm while passing through epididymis?

What is the main sperm carrier?

What passes through urethra?

What organ lies under the urinary bladder and surrounds the first part of the urethra?

What is the function of the female reproductive system?

Where ovaries situated and what is their function?

What happens if sperm does not fertilize the secondary oocyte?

How many layers does the uterus have, and what are they?

How do they call a small erectile structure, comparable to the male penis, which becomes engorged with blood during sexual excitement and is the female center of sexual sensation?

What is the nature and the function of the mammary glands?

Where are the testes situated?

What cells produce androgens?

What is the function of an acrosome?

What is the term for a coiled tube next to each testis receiving sperm from the seminiferous tubules?

What is the dilated continuation of the epididymis?

Where is the urethra situated?

What prevents urination during ejaculation?

What system is more complex: the male reproductive system or the female reproductive system?

What are the main organs of the female reproductive system?

How often the ovarian and menstrual cycles happen?

What is the uterus?

What are the parts of the vulva?

Where are the mammary glands situated?

What stimulates lactation during pregnancy?