Reproductive System

What is a somatic cell?

A diploid, non-reproductive cell (e.g., muscle, skin, nerve)

Are somatic cells haploid or diploid?

Diploid (2n)

Give an example of somatic cells.

Muscle, skin, nerve cells

What is a germ cell?

A diploid embryonic-origin cell that gives rise to gametes via meiosis

What is an example of a germ cell?

Spermatogonium or oogonium

What is a gamete?

A haploid sex cell (egg or sperm)

Are gametes haploid or diploid?

Haploid (n)

What process produces gametes?

Meiosis

What is viviparity?

Birth to live young nourished directly from the mother

What is oviparity?

Fertilized eggs are laid outside the mother and hatch later

What is ovoviviparity?

Fertilized eggs hatch inside the mother; young are nourished from yolk before live birth

What are gonads?

Reproductive organs that produce gametes

What are the male gonads?

Testes

What are the female gonads?

Ovaries

What is the function of the testicles?

Produce sperm and male sex hormones

What structure encloses the testes?

The scrotum

Why are the testes located in the scrotum?

Temperature regulation for sperm development

What structures are found inside the testes?

Seminiferous tubules

What happens in the seminiferous tubules?

Sperm production (spermatogenesis)

What type of cells are found in seminiferous tubules?

Sertoli cells and germ cells

What is the role of Sertoli cells?

Stimulated by FSH; nourish developing sperm

What is the role of Leydig (interstitial) cells?

Stimulated by LH; secrete testosterone and androgens

What is the function of the epididymis?

Stores and matures sperm

Where is the epididymis located?

Coiled tube on top of each testicle

What is the function of the vas deferens?

Transports sperm from epididymis to urethra

What is the function of the seminal vesicles?

Secrete fluid into the vas deferens during ejaculation

What is the function of the prostate gland?

Secretes fluid that nourishes and protects sperm

What is the function of the bulbourethral glands (Cowper’s glands)?

Secrete mucus for lubrication

What is the function of the penis?

Transfers semen into the vagina

What is the function of the ovaries?

Produce eggs (ova) and hormones

How many ovaries do females have?

Two

What is the function of the oviduct (fallopian tube)?

Transports egg from ovary to uterus

Where does fertilization occur in females?

In the fallopian tube

What structure sweeps the egg into the fallopian tube?

Fimbriae

What is the function of the uterus?

Muscular chamber where embryo implants and develops

What happens in the uterus after fertilization?

Zygote attaches to the uterine wall

What is the function of the cervix?

Connects uterus to vagina; opening for childbirth

What is the function of the vagina?

Muscular canal; serves as the birth canal and connects to uterus

What is found in the sperm head?

DNA, acrosome, pronucleus

What is the function of the acrosome?

Contains enzymes to penetrate the egg’s outer layer

What is the pronucleus of sperm?

Haploid nucleus with 23 chromosomes

What is the function of the sperm midpiece?

Contains mitochondria to provide energy for movement

What is the function of the sperm tail?

Flagellum that provides motility

What is the sperm pathway mnemonic?

SEVEn UP

What does "S" in SEVEn UP stand for?

Seminiferous tubules

What does "E" in SEVEn UP stand for?

Epididymis

What does "V" in SEVEn UP stand for?

Vas deferens

What does "E" in SEVEn UP stand for?

Ejaculatory duct

What does "n" in SEVEn UP stand for?

Nothing (placeholder)

What does "U" in SEVEn UP stand for?

Urethra

What does "P" in SEVEn UP stand for?

Penis

Where does fertilization normally occur?

In the fallopian tube

What happens immediately after sperm fertilizes the egg?

Zygote undergoes cleavage

What is cleavage?

Rapid cell divisions without growth

What does cleavage form?

A morula (solid ball of cells)

What does the morula develop into?

An early blastocyst

What does the blastocyst do?

Implants into the uterine lining

What happens on Day 1 after ovulation?

Ovulation and possible fertilization

What happens on Day 2–3?

Cleavage divisions occur

What is seen at Day 4 after fertilization?

Morula formation

What is seen at Day 5 after fertilization?

Early blastocyst

What is seen at Day 6–7 after fertilization?

Late blastocyst

What happens around Day 8–9 after fertilization?

Blastocyst implantation into uterus

When does the fetal heart begin to beat?

Week 5

When does embryo officially become fetus?

Week 8

When is full-term pregnancy reached?

Week 40

What is oogenesis?

The process of forming eggs (oocytes) in females

When does oogenesis begin?

Before birth

What happens to oogonia during fetal development?

They divide by mitosis to form primary oocytes

What stage do primary oocytes arrest in?

Prophase I

When do primary oocytes remain arrested until?

Puberty

What surrounds a primary oocyte in the ovary?

Granulosa cells → primordial follicle

What is a primordial follicle?

Primary oocyte + single layer of granulosa cells

What happens at puberty to primordial follicles?

They develop into primary follicles

What is a primary follicle?

Granulosa cells enlarge and increase in number around oocyte

What is a secondary follicle?

Fluid-filled vesicles appear, theca cells form outside

What is a mature follicle (Graafian follicle)?

Has a single large antrum filled with fluid

When does meiosis I finish in females?

Just before ovulation

What is produced at the end of meiosis I in females?

One secondary oocyte + one polar body

At what stage is the secondary oocyte arrested?

Metaphase II

When is meiosis II completed in females?

Only if fertilization occurs

What does the completion of meiosis II produce?

One ovum + a second polar body

What happens to the follicle after ovulation?

It becomes the corpus luteum

What does the corpus luteum secrete?

Estrogen and progesterone

What happens to corpus luteum if fertilization does not occur?

It degenerates into corpus albicans

What is corpus albicans?

Scar tissue left behind after corpus luteum degeneration

What is spermatogenesis?

Production of sperm cells in males

Where does spermatogenesis occur?

In the seminiferous tubules of testes

When does spermatogenesis begin?

At puberty

What is the starting cell in spermatogenesis?

Spermatogonium (2n)

What type of cell division do spermatogonia undergo?

Mitosis → produces more spermatogonia and primary spermatocytes

What does a primary spermatocyte undergo?

Meiosis I

What is produced from meiosis I of a primary spermatocyte?

Two secondary spermatocytes (haploid)

What does each secondary spermatocyte undergo?

Meiosis II

What is produced from meiosis II of secondary spermatocytes?

Four spermatids (haploid)

What is spermiogenesis?

Maturation of spermatids into spermatozoa (sperm)

How many sperm are produced from one spermatogonium?

Four

Where do mature sperm go after formation?

Epididymis for storage and maturation

What is the average length of the menstrual cycle?

28 days

What are the three main phases of the menstrual cycle?

Menses, proliferative phase, secretory phase